diff --git a/src/cli/index.tsx b/src/cli/index.tsx
index 1175f87..fe60568 100644
--- a/src/cli/index.tsx
+++ b/src/cli/index.tsx
@@ -3,6 +3,9 @@ import { logger, LogLevel } from "../lib/utils/logger.ts";
 import { statSync } from "node:fs";
 import { scanDirectoryForImages } from "../utils/app-utils.ts";
 import type { UploadOptions, StatusOptions } from "./types.ts";
+import { render } from "ink";
+import { App } from "../components/App.tsx";
+import { StatusApp } from "../components/StatusApp.tsx";
 
 export function setupCLI() {
   const program = new Command();
@@ -24,6 +27,7 @@ export function setupCLI() {
     )
     .option("--address <address>", "BLE device address (optional)")
     .option("--size <size>", "Target size WxH", "368x368")
+    .option("--animation-size <size>", "Animation size WxH", "360x360")
     .option("--test", "Upload 8x8 checkerboard test pattern", false)
     .option("--packet-delay <ms>", "Delay between packets in milliseconds", "20")
     .action(async (imageArg: string | undefined, options: UploadOptions) => {
@@ -90,8 +94,13 @@ export function setupCLI() {
         process.exit(1);
       }
 
-      const { App } = await import("../components/App.tsx");
-      const { render } = await import("ink");
+      if (!sizeRegex.test(options.animationSize)) {
+        console.error(
+          "Error: Invalid animation size format. Use WIDTHxHEIGHT (e.g., 360x360)",
+        );
+        process.exit(1);
+      }
+
       render(<App options={options} verbose={verbose} />);
     });
 
@@ -107,8 +116,6 @@ export function setupCLI() {
         logger.setLevel(LogLevel.DEBUG);
       }
 
-      const { StatusApp } = await import("../components/StatusApp.tsx");
-      const { render } = await import("ink");
       render(<StatusApp options={options} verbose={verbose} />);
     });
 
diff --git a/src/cli/types.ts b/src/cli/types.ts
index efae702..30ae43c 100644
--- a/src/cli/types.ts
+++ b/src/cli/types.ts
@@ -2,6 +2,7 @@ export interface UploadOptions {
   image?: string;
   address?: string;
   size: string;
+  animationSize: string;
   test: boolean;
   packetDelay: number;
   images?: string[];
diff --git a/src/hooks/useUpload.ts b/src/hooks/useUpload.ts
index 84c2fa8..979dfb5 100644
--- a/src/hooks/useUpload.ts
+++ b/src/hooks/useUpload.ts
@@ -110,6 +110,13 @@ export function useUpload(options: UploadOptions, verbose: boolean) {
       try {
         const [width, height] = options.size.split("x").map(Number);
         const targetSize: [number, number] = [width!, height!];
+        const [animationWidth, animationHeight] = options.animationSize
+          .split("x")
+          .map(Number);
+        const animationSize: [number, number] = [
+          animationWidth!,
+          animationHeight!,
+        ];
         const packetDelaySeconds = options.packetDelay / 1000.0;
 
         const isBulk =
@@ -169,16 +176,18 @@ export function useUpload(options: UploadOptions, verbose: boolean) {
             ]);
             setProgress(0);
 
-            const success = await uploader.uploadImageFromFile(
-              imagePath,
-              targetSize,
-              (prog, status) => {
-                setProgress(prog);
-                if (status) {
-                  setMessage(`${i + 1}/${imagesToUpload.length}: ${status}`);
-                }
-              },
-            );
+              const success = await uploader.uploadImageFromFile(
+                imagePath,
+                targetSize,
+                animationSize,
+                (prog: number, status?: string) => {
+                  setProgress(prog);
+                  if (status) {
+                    setMessage(`${i + 1}/${imagesToUpload.length}: ${status}`);
+                  }
+                },
+              );
+
 
             if (!success) {
               throw new Error(`Failed to upload ${fileName}`);
@@ -203,17 +212,22 @@ export function useUpload(options: UploadOptions, verbose: boolean) {
 
           let success: boolean;
           if (options.test) {
-            success = await uploader.uploadCheckerboard(targetSize, 8, (prog, status) => {
-              setProgress(prog);
-              if (status) {
-                setMessage(status);
-              }
-            });
+            success = await uploader.uploadCheckerboard(
+              targetSize,
+              8,
+              (prog: number, status?: string) => {
+                setProgress(prog);
+                if (status) {
+                  setMessage(status);
+                }
+              },
+            );
           } else if (options.image) {
             success = await uploader.uploadImageFromFile(
               options.image,
               targetSize,
-              (prog, status) => {
+              animationSize,
+              (prog: number, status?: string) => {
                 setProgress(prog);
                 if (status) {
                   setMessage(status);
diff --git a/src/lib/core/beambox-uploader.ts b/src/lib/core/beambox-uploader.ts
index 9bf7f2d..f5cd86d 100644
--- a/src/lib/core/beambox-uploader.ts
+++ b/src/lib/core/beambox-uploader.ts
@@ -21,6 +21,7 @@ export interface UploadOptions {
   imagePath?: string;
   imageData?: Buffer;
   targetSize?: [number, number];
+  animationSize?: [number, number];
   onProgress?: (progress: number, status?: string) => void;
 }
 
@@ -84,13 +85,16 @@ export class BeamBoxUploader {
    * @returns True if upload successful
    */
   public async upload(options: UploadOptions): Promise<boolean> {
-    const { imagePath, imageData, targetSize, onProgress } = options;
+    const { imagePath, imageData, targetSize, animationSize, onProgress } =
+      options;
 
     if (!imageData && !imagePath) {
       throw new UploadError("No image provided");
     }
 
     const effectiveSize = targetSize ?? this.imageConfig.defaultSize;
+    const effectiveAnimationSize =
+      animationSize ?? this.imageConfig.animationsSize;
 
     // Detect file type if path provided
     let isAnimated = false;
@@ -104,7 +108,11 @@ export class BeamBoxUploader {
 
       if (isAnimated) {
         logger.info("File is animated, using Type 5 (DYNAMIC_AMBIENCE)");
-        return await this.uploadAnimation(imagePath, effectiveSize, onProgress);
+        return await this.uploadAnimation(
+          imagePath,
+          effectiveAnimationSize,
+          onProgress,
+        );
       } else {
         logger.info("File is static image, using Type 6 (IMAGE)");
       }
@@ -176,20 +184,39 @@ export class BeamBoxUploader {
     targetSize: [number, number],
     onProgress?: (progress: number) => void,
   ): Promise<boolean> {
+    const animationSize: [number, number] = targetSize;
+    
     // Extract frames from the file
-    logger.info("Extracting frames from animation...");
+    logger.info(
+      `Extracting frames from animation at ${animationSize[0]}x${animationSize[1]}...`,
+    );
     const frames = await FrameExtractor.extractFrames(filePath, {
-      maxFrames: 100,
-      targetSize,
+      targetSize: animationSize,
     });
 
     logger.info(`Extracted ${frames.length} frames`);
 
+    // Ensure minimum 2 frames for device compatibility
+    // The xV4 format requires at least 2 frames
+    const MIN_FRAMES = 2;
+    if (frames.length < MIN_FRAMES) {
+      logger.info(`Padding from ${frames.length} to ${MIN_FRAMES} frames by duplicating last frame`);
+      while (frames.length < MIN_FRAMES) {
+        const lastFrame = frames[frames.length - 1]!;
+        frames.push({
+          name: `frame_${String(frames.length + 1).padStart(5, '0')}`,
+          data: lastFrame.data, // Reuse the same buffer
+        });
+      }
+      logger.info(`Padded to ${frames.length} frames`);
+    }
+
     // Calculate frame interval
-    const intervalMs = await FrameExtractor.calculateFrameInterval(
-      filePath,
-      frames.length,
-    );
+    // Based on analysis: working animations use 50ms interval
+    // TODO: Experiment with different intervals later
+    // The timing string must fit in 12 bytes ("output/XXms\0"), so intervals
+    // must be 2 digits (10-99). Using 50ms as it's proven to work.
+    const intervalMs = 50;
     logger.info(`Using frame interval: ${intervalMs}ms`);
 
     // Wait for device to be ready
@@ -208,7 +235,7 @@ export class BeamBoxUploader {
     const fullData = this.payloadBuilder.buildAnimationData(
       frames,
       intervalMs,
-      targetSize,
+      animationSize,
     );
 
     logger.info(
@@ -247,9 +274,10 @@ export class BeamBoxUploader {
   public async uploadImageFromFile(
     imagePath: string,
     targetSize?: [number, number],
+    animationSize?: [number, number],
     onProgress?: (progress: number, status?: string) => void,
   ): Promise<boolean> {
-    return await this.upload({ imagePath, targetSize, onProgress });
+    return await this.upload({ imagePath, targetSize, animationSize, onProgress });
   }
 
   /**
diff --git a/src/lib/processing/frame-extractor.ts b/src/lib/processing/frame-extractor.ts
index fb00274..9c34603 100644
--- a/src/lib/processing/frame-extractor.ts
+++ b/src/lib/processing/frame-extractor.ts
@@ -3,6 +3,7 @@ import { promisify } from "util";
 import { mkdtemp, readdir, readFile, rm } from "fs/promises";
 import { tmpdir } from "os";
 import { join } from "path";
+import sharp from "sharp";
 import type { XV4Frame } from "../protocol/index.ts";
 import { ImageProcessingError } from "../utils/errors.ts";
 import { logger } from "../utils/logger.ts";
@@ -10,8 +11,6 @@ import { logger } from "../utils/logger.ts";
 const execAsync = promisify(exec);
 
 export interface FrameExtractionOptions {
-  /** Maximum number of frames to extract (default: 100) */
-  maxFrames?: number;
   /** Target FPS for extraction (default: extract all frames) */
   fps?: number;
   /** Target size for frames [width, height] */
@@ -32,11 +31,7 @@ export class FrameExtractor {
     filePath: string,
     options: FrameExtractionOptions = {},
   ): Promise<XV4Frame[]> {
-    const {
-      maxFrames = 100,
-      fps = null,
-      targetSize = [368, 368],
-    } = options;
+    const { fps = null, targetSize = [360, 360] } = options;
 
     // Create temporary directory for frames
     const tempDir = await mkdtemp(join(tmpdir(), "beambox-frames-"));
@@ -56,20 +51,21 @@ export class FrameExtractor {
         filters.push(`fps=${fps}`);
       }
 
-      // Add scaling and padding
-      filters.push(`scale=${targetSize[0]}:${targetSize[1]}:force_original_aspect_ratio=decrease`);
-      filters.push(`pad=${targetSize[0]}:${targetSize[1]}:(ow-iw)/2:(oh-ih)/2`);
+      // Add scaling and cropping to fill frame (official app does this)
+      // Use 'increase' to scale up to fill, then crop to exact dimensions
+      filters.push(
+        `scale=${targetSize[0]}:${targetSize[1]}:force_original_aspect_ratio=increase`,
+      );
+      filters.push(`crop=${targetSize[0]}:${targetSize[1]}`);
 
       // Combine all filters
       if (filters.length > 0) {
-        ffmpegCmd += ` -vf "${filters.join(',')}"`;
+        ffmpegCmd += ` -vf "${filters.join(",")}"`;
       }
 
-      // Add frame limit
-      ffmpegCmd += ` -vframes ${maxFrames}`;
-
       // Add quality settings
-      ffmpegCmd += ` -q:v 2`; // High quality JPEG
+      // Use -q:v 10 for initial extraction (will be re-encoded with Sharp)
+      ffmpegCmd += ` -q:v 10`;
 
       ffmpegCmd += ` "${outputPattern}"`;
 
@@ -79,7 +75,7 @@ export class FrameExtractor {
       const { stdout, stderr } = await execAsync(ffmpegCmd);
 
       if (stderr && !stderr.includes("frame=")) {
-        logger.warn(`ffmpeg stderr: ${stderr}`);
+        logger.warning(`ffmpeg stderr: ${stderr}`);
       }
 
       // Read extracted frames
@@ -97,19 +93,72 @@ export class FrameExtractor {
       logger.info(`Extracted ${frameFiles.length} frames`);
 
       // Load frames into XV4Frame format
-      const frames: XV4Frame[] = [];
-      for (const file of frameFiles) {
-        const framePath = join(tempDir, file);
-        const data = await readFile(framePath);
+      // Re-encode frames to ensure consistent JPEG format
+      logger.info("Re-encoding frames to quality 75...");
 
-        // Extract frame number from filename (e.g., "frame_00001.jpg" -> "frame_00001")
+      // Standard JFIF APP0 marker segment (18 bytes)
+      // This marker is required for some devices to properly decode the JPEG
+      // Structure: FF E0 + length (16) + 'JFIF\0' + version 1.1 + aspect ratio + density
+      const jfifMarker = Buffer.from([
+        0xff,
+        0xe0, // APP0 marker
+        0x00,
+        0x10, // Length: 16 bytes (including these 2)
+        0x4a,
+        0x46,
+        0x49,
+        0x46,
+        0x00, // 'JFIF\0'
+        0x01,
+        0x01, // Version 1.1
+        0x00, // Aspect ratio units: 0 = no units
+        0x00,
+        0x01, // X density: 1
+        0x00,
+        0x01, // Y density: 1
+        0x00,
+        0x00, // No thumbnail
+      ]);
+
+      // Process frames in parallel for speed
+      const framePromises = frameFiles.map(async (file) => {
+        const framePath = join(tempDir, file);
+
+        // Decode and re-encode to ensure consistent JPEG format with quality 75
+        // This should match official app settings:
+        // with Chroma subsampling: 4:4:4 (no subsampling, highest quality)
+        const reencoded = await sharp(framePath)
+          .jpeg({
+            quality: 75,
+            optimiseCoding: true,
+            mozjpeg: false,
+            chromaSubsampling: "4:4:4",
+          })
+          .toBuffer();
+
+        // Inject JFIF marker after SOI (FF D8)
+        // Sharp doesn't include JFIF by default, but the device may require it? Just to be safe.
+        // SOI is always at the start: FF D8
+        const withJfif = Buffer.concat([
+          reencoded.subarray(0, 2), // SOI (FF D8)
+          jfifMarker, // JFIF APP0 marker
+          reencoded.subarray(2), // Rest of JPEG data
+        ]);
+
+        // Extract frame number from filename like ("frame_00001.jpg" -> "frame_00001")
         const name = file.replace(".jpg", "");
 
-        frames.push({
+        return {
           name,
-          data,
-        });
-      }
+          data: withJfif,
+        };
+      });
+
+      const frames = await Promise.all(framePromises);
+      const totalSize = frames.reduce((sum, f) => sum + f.data.length, 0);
+      logger.info(
+        `Re-encoding complete. Total JPEG data: ${(totalSize / 1024).toFixed(2)} KB`,
+      );
 
       return frames;
     } catch (error) {
@@ -125,11 +174,39 @@ export class FrameExtractor {
       try {
         await rm(tempDir, { recursive: true, force: true });
       } catch (error) {
-        logger.warn(`Failed to clean up temp directory: ${error}`);
+        logger.warning(`Failed to clean up temp directory: ${error}`);
       }
     }
   }
 
+  /**
+   * Calculate GIF frame interval using app logic
+   *
+   * The app uses frame-count-based intervals for GIFs:
+   * - <=12 frames: 200ms (5 fps)
+   * - <=24 frames: 150ms (6.7 fps)
+   * - >24 frames: 100ms (10 fps)
+   *
+   * This is then clamped to [50, 300]ms range.
+   *
+   * @param frameCount Number of extracted frames
+   * @returns Frame interval in milliseconds
+   */
+  static calculateGifInterval(frameCount: number): number {
+    let interval: number;
+
+    if (frameCount <= 12) {
+      interval = 200;
+    } else if (frameCount <= 24) {
+      interval = 150;
+    } else {
+      interval = 100;
+    }
+
+    // Clamp to [50, 300]ms range
+    return Math.max(50, Math.min(300, interval));
+  }
+
   /**
    * Get frame rate of a video file
    * @param filePath Path to the video file
@@ -150,7 +227,7 @@ export class FrameExtractor {
 
       return 30; // Default fallback
     } catch (error) {
-      logger.warn(`Failed to get frame rate: ${error}`);
+      logger.warning(`Failed to get frame rate: ${error}`);
       return 30; // Default fallback
     }
   }
@@ -166,16 +243,20 @@ export class FrameExtractor {
       const { stdout } = await execAsync(cmd);
       return parseFloat(stdout.trim());
     } catch (error) {
-      logger.warn(`Failed to get duration: ${error}`);
+      logger.warning(`Failed to get duration: ${error}`);
       return 0;
     }
   }
 
   /**
-   * Calculate recommended frame interval in milliseconds based on extracted frames and original duration
+   * Calculate recommended frame interval in milliseconds
+   *
+   * Calculates the interval to preserve the original animation duration
+   * based on source duration and actual extracted frame count.
+   *
    * @param filePath Path to the source file
    * @param extractedFrameCount Number of frames that were extracted
-   * @returns Recommended interval in milliseconds
+   * @returns Frame interval in milliseconds
    */
   static async calculateFrameInterval(
     filePath: string,
@@ -186,9 +267,12 @@ export class FrameExtractor {
     if (duration > 0 && extractedFrameCount > 1) {
       // Calculate interval to maintain original playback speed
       const intervalMs = (duration * 1000) / extractedFrameCount;
-      return Math.max(20, Math.round(intervalMs)); // Minimum 20ms (50fps)
+      // Device requires minimum 150ms interval to play animations? Maybe, from trials and errors.
+      // Below 150ms, the device shows only the first frame, somtimes?
+      // Need more testing to confirm.
+      return Math.max(150, Math.round(intervalMs));
     }
 
-    return 50; // Default 50ms (20fps)
+    return 150; // Default 150ms (~6.7fps), device minimum for animation?
   }
 }
diff --git a/src/lib/processing/image-processor.test.ts b/src/lib/processing/image-processor.test.ts
index fbf06bf..a45c838 100644
--- a/src/lib/processing/image-processor.test.ts
+++ b/src/lib/processing/image-processor.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect } from "bun:test";
+import { describe, test, expect } from "vitest";
 import { ImageProcessor } from "./image-processor.ts";
 import { ImageProcessingError } from "../utils/errors.ts";
 import { DEFAULT_IMAGE_CONFIG } from "../protocol/interfaces/defaults.ts";
diff --git a/src/lib/processing/image-processor.ts b/src/lib/processing/image-processor.ts
index 32e1b57..ac5ddfc 100644
--- a/src/lib/processing/image-processor.ts
+++ b/src/lib/processing/image-processor.ts
@@ -62,11 +62,35 @@ export class ImageProcessor {
     }
   }
 
+  // Standard JFIF APP0 marker segment (18 bytes)
+  // This marker is required for some devices to properly decode the JPEG
+  // Structure: FF E0 + length (16) + 'JFIF\0' + version 1.1 + aspect ratio + density
+  private static readonly JFIF_MARKER = Buffer.from([
+    0xff,
+    0xe0, // APP0 marker
+    0x00,
+    0x10, // Length: 16 bytes (including these 2)
+    0x4a,
+    0x46,
+    0x49,
+    0x46,
+    0x00, // 'JFIF\0'
+    0x01,
+    0x01, // Version 1.1
+    0x00, // Aspect ratio units: 0 = no units
+    0x00,
+    0x01, // X density: 1
+    0x00,
+    0x01, // Y density: 1
+    0x00,
+    0x00, // No thumbnail
+  ]);
+
   /**
    * Prepare an image as JPEG bytes
    * @param imageInput Sharp instance or buffer
    * @param targetSize Target size [width, height]
-   * @returns JPEG image as Buffer
+   * @returns JPEG image as Buffer with JFIF marker
    */
   public async prepareImage(
     imageInput: sharp.Sharp | Buffer,
@@ -77,9 +101,10 @@ export class ImageProcessor {
         ? sharp(imageInput)
         : imageInput;
 
-      return await pipeline
+      const jpegData = await pipeline
         .resize(targetSize[0], targetSize[1], {
-          fit: "fill",
+          fit: "cover", // Use 'cover' to fill frame (official app does scale increase + crop)
+          position: "center",
           kernel: "lanczos3",
         })
         .toColorspace("srgb")
@@ -90,6 +115,14 @@ export class ImageProcessor {
           chromaSubsampling: "4:2:0",
         })
         .toBuffer();
+
+      // Inject JFIF marker after SOI (FF D8)
+      // Sharp doesn't include JFIF by default, but the device may require it? Just to be safe.
+      return Buffer.concat([
+        jpegData.subarray(0, 2), // SOI (FF D8)
+        ImageProcessor.JFIF_MARKER, // JFIF APP0 marker
+        jpegData.subarray(2), // Rest of JPEG data
+      ]);
     } catch (error) {
       throw new ImageProcessingError(`Failed to prepare image: ${error}`);
     }
diff --git a/src/lib/processing/media-detector.test.ts b/src/lib/processing/media-detector.test.ts
index 282977e..8e5733a 100644
--- a/src/lib/processing/media-detector.test.ts
+++ b/src/lib/processing/media-detector.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect } from "bun:test";
+import { describe, it, expect } from "vitest";
 import { MediaDetector } from "./media-detector.ts";
 
 describe("MediaDetector", () => {
diff --git a/src/lib/protocol/builders/imb-header.test.ts b/src/lib/protocol/builders/imb-header.test.ts
index 5df98ee..2bc1a8b 100644
--- a/src/lib/protocol/builders/imb-header.test.ts
+++ b/src/lib/protocol/builders/imb-header.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect } from "bun:test";
+import { describe, test, expect } from "vitest";
 import { IMBHeaderBuilder } from "./imb-header.ts";
 import { expectHex } from "../../../__tests__/utils/test-helpers.ts";
 
diff --git a/src/lib/protocol/builders/payload-builder.test.ts b/src/lib/protocol/builders/payload-builder.test.ts
index 3e49a22..4043b96 100644
--- a/src/lib/protocol/builders/payload-builder.test.ts
+++ b/src/lib/protocol/builders/payload-builder.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect } from "bun:test";
+import { describe, test, expect } from "vitest";
 import { PayloadBuilder } from "./payload-builder.ts";
 import { PacketType } from "../packet-types.ts";
 import { DEFAULT_PROTOCOL_CONFIG } from "../interfaces/defaults.ts";
@@ -151,7 +151,7 @@ describe("PayloadBuilder", () => {
           data: createTestJpeg(100),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 50, [368, 368]);
+      const payload = createBuilder().buildAnimationData(frames, 50, [360, 360]);
       const text = payload.toString("utf-8", 0, 15);
       expect(text).toMatch(/^\{"type":5,"data/);
     });
@@ -163,7 +163,7 @@ describe("PayloadBuilder", () => {
           data: createTestJpeg(100),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 50, [368, 368]);
+      const payload = createBuilder().buildAnimationData(frames, 50, [360, 360]);
       const prefix = payload.toString("utf-8", 0, 17);
       expect(prefix).toBe('{"type":5,"data":');
     });
@@ -175,7 +175,7 @@ describe("PayloadBuilder", () => {
           data: createTestJpeg(100),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 50, [368, 368]);
+      const payload = createBuilder().buildAnimationData(frames, 50, [360, 360]);
       const lastByte = payload.toString("utf-8", payload.length - 1);
       expect(lastByte).toBe("}");
     });
@@ -187,7 +187,7 @@ describe("PayloadBuilder", () => {
           data: createTestJpeg(100),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 50, [368, 368]);
+      const payload = createBuilder().buildAnimationData(frames, 50, [360, 360]);
       const prefixLen = '{"type":5,"data":'.length;
       const xv4Sig = payload.toString("utf-8", prefixLen, prefixLen + 3);
       expect(xv4Sig).toBe("xV4");
@@ -208,7 +208,7 @@ describe("PayloadBuilder", () => {
           data: createTestJpeg(120),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 50, [368, 368]);
+      const payload = createBuilder().buildAnimationData(frames, 50, [360, 360]);
 
       // Check it has proper structure
       const prefixLen = '{"type":5,"data":'.length;
@@ -220,25 +220,35 @@ describe("PayloadBuilder", () => {
       expect(frameCount).toBe(3);
     });
 
-    test("custom interval creates correct timing string", () => {
+    test("timing string uses interval value (clamped to 50-99)", () => {
       const frames: XV4Frame[] = [
         {
           name: "frame_00001",
           data: createTestJpeg(100),
         },
       ];
-      const payload = createBuilder().buildAnimationData(frames, 100, [368, 368]);
+      // 100ms interval gets clamped to 99ms for the timing string
+      const payload = createBuilder().buildAnimationData(frames, 100, [360, 360]);
 
       // The timing string is embedded in the xV4 container
       const prefixLen = '{"type":5,"data":'.length;
       const xv4Start = prefixLen;
 
-      // Timing string is at offset 16 (xV4 + ver + unk + pad + count + size)
+      // Timing string is at offset 16, 12 bytes total
       const timingString = payload
-        .subarray(xv4Start + 16, xv4Start + 35)
+        .subarray(xv4Start + 16, xv4Start + 28)
         .toString("utf8")
         .replace(/\0.*$/, "");
-      expect(timingString).toBe("output/100ms");
+      // Timing string must fit in 12 bytes, so intervals are clamped to 50-99
+      expect(timingString).toBe("output/99ms");
+
+      // Test with 50ms interval
+      const payload50 = createBuilder().buildAnimationData(frames, 50, [360, 360]);
+      const timingString50 = payload50
+        .subarray(xv4Start + 16, xv4Start + 28)
+        .toString("utf8")
+        .replace(/\0.*$/, "");
+      expect(timingString50).toBe("output/50ms");
     });
   });
 
diff --git a/src/lib/protocol/builders/payload-builder.ts b/src/lib/protocol/builders/payload-builder.ts
index fb87ae7..6bf5767 100644
--- a/src/lib/protocol/builders/payload-builder.ts
+++ b/src/lib/protocol/builders/payload-builder.ts
@@ -1,6 +1,7 @@
 import type { ProtocolConfig } from "../interfaces/config.ts";
 import { PacketType } from "../packet-types.ts";
 import { IMBHeaderBuilder } from "./imb-header.ts";
+import { DEFAULT_IMAGE_CONFIG } from "../interfaces/defaults.ts";
 import { XV4HeaderBuilder, type XV4Frame } from "./xv4-header.ts";
 
 /**
@@ -44,13 +45,13 @@ export class PayloadBuilder {
    *
    * @param frames Array of frames with names and JPEG data
    * @param intervalMs Frame interval in milliseconds (default: 50ms = 20fps)
-   * @param targetSize Image dimensions [width, height] (default: [368, 368])
+   * @param targetSize Image dimensions [width, height] (default: [360, 360])
    * @returns Animation data payload bytes in format: {"type":5,"data":<xV4_BINARY>}
    */
   public buildAnimationData(
     frames: XV4Frame[],
     intervalMs: number = 50,
-    targetSize: [number, number] = [368, 368],
+    targetSize: [number, number] = DEFAULT_IMAGE_CONFIG.animationsSize,
   ): Buffer {
     const dataPrefix = Buffer.from(
       `{"type":${PacketType.DYNAMIC_AMBIENCE},"data":`,
diff --git a/src/lib/protocol/builders/xv4-header.test.ts b/src/lib/protocol/builders/xv4-header.test.ts
index 5e56e4f..f19de09 100644
--- a/src/lib/protocol/builders/xv4-header.test.ts
+++ b/src/lib/protocol/builders/xv4-header.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect } from "bun:test";
+import { describe, it, expect } from "vitest";
 import { XV4HeaderBuilder, type XV4Frame } from "./xv4-header.ts";
 
 describe("XV4HeaderBuilder", () => {
@@ -11,7 +11,7 @@ describe("XV4HeaderBuilder", () => {
         },
       ];
 
-      const container = XV4HeaderBuilder.build(frames, 50, 368, 368);
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
 
       // Check signature
       expect(container.subarray(0, 3).toString("ascii")).toBe("xV4");
@@ -19,11 +19,14 @@ describe("XV4HeaderBuilder", () => {
       // Check version
       expect(container.readUInt8(3)).toBe(0x12);
 
-      // Check unknown byte
-      expect(container.readUInt8(4)).toBe(0x48);
+      // Check header_size field (offset 4) = frame_table_end - 8 = (32 + 1*16) - 8 = 40
+      expect(container.readUInt32LE(4)).toBe(40);
 
-      // Check frame count (offset 8, u32 LE)
+      // Check frame count (offset 8)
       expect(container.readUInt32LE(8)).toBe(1);
+
+      // Check unknown field (offset 12) = frame_count * 10 + 10 = 20
+      expect(container.readUInt32LE(12)).toBe(20);
     });
 
     it("should create a valid xV4 container with multiple frames", () => {
@@ -42,11 +45,17 @@ describe("XV4HeaderBuilder", () => {
         },
       ];
 
-      const container = XV4HeaderBuilder.build(frames, 50, 368, 368);
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
 
-      // Check frame count (offset 8, u32 LE)
+      // Check header_size field = (32 + 3*16) - 8 = 72
+      expect(container.readUInt32LE(4)).toBe(72);
+
+      // Check frame count (offset 8)
       expect(container.readUInt32LE(8)).toBe(3);
 
+      // Check total data size (offset 28) = 3 * (32 + 6) = 114 (metadata + jpeg per frame)
+      expect(container.readUInt32LE(28)).toBe(114);
+
       // Validate it's a proper xV4 container
       expect(XV4HeaderBuilder.validate(container)).toBe(true);
     });
@@ -59,21 +68,188 @@ describe("XV4HeaderBuilder", () => {
         },
       ];
 
-      const container = XV4HeaderBuilder.build(frames, 100, 368, 368);
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
 
-      // Timing string is after: xV4 (3) + ver (1) + unk (1) + pad (3) + count (4) + size (4) = offset 16
+      // Timing string is at offset 16, 12 bytes
       const timingString = container
-        .subarray(16, 35)
+        .subarray(16, 28)
         .toString("utf8")
         .replace(/\0.*$/, "");
-      expect(timingString).toBe("output/100ms");
+      expect(timingString).toBe("output/50ms");
+    });
+
+    it("should use interval value in timing string (clamped to 50-99)", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.from([0xff, 0xd8, 0xff, 0xe0]),
+        },
+      ];
+
+      // Test with 99ms interval (within range)
+      const container99 = XV4HeaderBuilder.build(frames, 99, 360, 360);
+      const timingString99 = container99
+        .subarray(16, 28)
+        .toString("utf8")
+        .replace(/\0.*$/, "");
+      expect(timingString99).toBe("output/99ms");
+
+      // Test with 100ms interval (clamped to 99)
+      const container100 = XV4HeaderBuilder.build(frames, 100, 360, 360);
+      const timingString100 = container100
+        .subarray(16, 28)
+        .toString("utf8")
+        .replace(/\0.*$/, "");
+      expect(timingString100).toBe("output/99ms");
+
+      // Test with 30ms interval (clamped to 50)
+      const container30 = XV4HeaderBuilder.build(frames, 30, 360, 360);
+      const timingString30 = container30
+        .subarray(16, 28)
+        .toString("utf8")
+        .replace(/\0.*$/, "");
+      expect(timingString30).toBe("output/50ms");
     });
 
     it("should throw error with no frames", () => {
       expect(() => {
-        XV4HeaderBuilder.build([], 50, 368, 368);
+        XV4HeaderBuilder.build([], 50, 360, 360);
       }).toThrow("At least one frame is required");
     });
+
+    it("should include frame names with dot suffix in frame table", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.from([0xff, 0xd8, 0xff, 0xe0]),
+        },
+      ];
+
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
+
+      // Frame table starts at offset 32
+      // Each entry: 12-byte name + 4-byte offset
+      const frameName = container.subarray(32, 44).toString("utf8");
+      expect(frameName).toBe("frame_00001.");
+    });
+
+    it("should calculate cumulative offsets correctly", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.alloc(100), // 100 bytes
+        },
+        {
+          name: "frame_00002",
+          data: Buffer.alloc(200), // 200 bytes
+        },
+        {
+          name: "frame_00003",
+          data: Buffer.alloc(150), // 150 bytes
+        },
+      ];
+
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
+
+      // Frame table end = 32 + 3*16 = 80
+      const frameTableEnd = 80;
+
+      // Frame table offsets (each frame's metadata position):
+      // Frame 0: frameTableEnd + 0 = 80
+      // Frame 1: frameTableEnd + (32 + 100) = 80 + 132 = 212
+      // Frame 2: frameTableEnd + (32 + 100) + (32 + 200) = 80 + 132 + 232 = 444
+
+      expect(container.readUInt32LE(32 + 12)).toBe(frameTableEnd); // Frame 0 offset
+      expect(container.readUInt32LE(48 + 12)).toBe(frameTableEnd + 32 + 100); // Frame 1 offset
+      expect(container.readUInt32LE(64 + 12)).toBe(frameTableEnd + 32 + 100 + 32 + 200); // Frame 2 offset
+    });
+
+    it("should place JPEG data after metadata block for each frame", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.from([0xff, 0xd8, 0xff, 0xe0]),
+        },
+        {
+          name: "frame_00002",
+          data: Buffer.from([0xff, 0xd8, 0xff, 0xe1]),
+        },
+      ];
+
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
+
+      // Frame table end = 32 + 2*16 = 64
+      // Frame 0 metadata at 64, JPEG at 64+32 = 96
+      const jpegOffset = 64 + 32;
+
+      // First frame's JPEG SOI marker
+      expect(container.readUInt16BE(jpegOffset)).toBe(0xffd8);
+    });
+
+    it("should include correct per-frame metadata structure", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.from([0xff, 0xd8, 0x00, 0x01, 0x02, 0x03]), // 6 bytes
+        },
+        {
+          name: "frame_00002",
+          data: Buffer.from([0xff, 0xd8, 0x10, 0x11]), // 4 bytes
+        },
+      ];
+
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
+
+      // Frame table end = 32 + 2*16 = 64
+      const frameTableEnd = 64;
+      
+      // Frame 0 metadata at offset 64
+      const meta0 = frameTableEnd;
+      const jpeg0 = meta0 + 32; // JPEG starts after 32-byte metadata
+      
+      // Frame 1 metadata at offset 64 + 32 + 6 = 102
+      const meta1 = meta0 + 32 + 6;
+      const jpeg1 = meta1 + 32;
+
+      // Frame 0 metadata structure:
+      // [0-3] Current frame table offset
+      expect(container.readUInt32LE(meta0)).toBe(meta0);
+
+      // [4-7] Next frame table offset (points to frame 1 metadata)
+      expect(container.readUInt32LE(meta0 + 4)).toBe(meta1);
+
+      // [8-11] Unknown value = frame_count - 3 = -1 clamped to 0
+      expect(container.readUInt32LE(meta0 + 8)).toBe(0);
+
+      // [12-13] Width
+      expect(container.readUInt16LE(meta0 + 12)).toBe(360);
+
+      // [14-15] Height
+      expect(container.readUInt16LE(meta0 + 14)).toBe(360);
+
+      // [16-19] JPEG data start offset
+      expect(container.readUInt32LE(meta0 + 16)).toBe(jpeg0);
+
+      // [20-23] Frame 0 JPEG size
+      expect(container.readUInt32LE(meta0 + 20)).toBe(6);
+
+      // [24-31] Padding zeros
+      expect(container.readUInt32LE(meta0 + 24)).toBe(0);
+      expect(container.readUInt32LE(meta0 + 28)).toBe(0);
+
+      // Frame 1 metadata structure:
+      // [0-3] Current frame table offset
+      expect(container.readUInt32LE(meta1)).toBe(meta1);
+
+      // [4-7] Next frame table offset (loops back to first frame for continuous playback)
+      expect(container.readUInt32LE(meta1 + 4)).toBe(meta0);
+
+      // [16-19] JPEG data start offset
+      expect(container.readUInt32LE(meta1 + 16)).toBe(jpeg1);
+
+      // [20-23] Frame 1 JPEG size
+      expect(container.readUInt32LE(meta1 + 20)).toBe(4);
+    });
   });
 
   describe("validate", () => {
@@ -85,7 +261,7 @@ describe("XV4HeaderBuilder", () => {
         },
       ];
 
-      const container = XV4HeaderBuilder.build(frames, 50, 368, 368);
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
       expect(XV4HeaderBuilder.validate(container)).toBe(true);
     });
 
@@ -95,30 +271,43 @@ describe("XV4HeaderBuilder", () => {
     });
 
     it("should reject buffer with wrong signature", () => {
-      const buffer = Buffer.alloc(20);
+      const buffer = Buffer.alloc(40);
       buffer.write("ABC", 0);
       buffer.writeUInt8(0x12, 3);
-      buffer.writeUInt8(0x48, 4);
 
       expect(XV4HeaderBuilder.validate(buffer)).toBe(false);
     });
 
     it("should reject buffer with wrong version", () => {
-      const buffer = Buffer.alloc(20);
+      const buffer = Buffer.alloc(40);
       buffer.write("xV4", 0);
       buffer.writeUInt8(0x99, 3); // Wrong version
-      buffer.writeUInt8(0x48, 4);
-
-      expect(XV4HeaderBuilder.validate(buffer)).toBe(false);
-    });
-
-    it("should reject buffer with wrong unknown byte", () => {
-      const buffer = Buffer.alloc(20);
-      buffer.write("xV4", 0);
-      buffer.writeUInt8(0x12, 3);
-      buffer.writeUInt8(0x99, 4); // Wrong unknown byte
 
       expect(XV4HeaderBuilder.validate(buffer)).toBe(false);
     });
   });
+
+  describe("dump", () => {
+    it("should dump xV4 container structure", () => {
+      const frames: XV4Frame[] = [
+        {
+          name: "frame_00001",
+          data: Buffer.alloc(100),
+        },
+        {
+          name: "frame_00002",
+          data: Buffer.alloc(200),
+        },
+      ];
+
+      const container = XV4HeaderBuilder.build(frames, 50, 360, 360);
+      const dump = XV4HeaderBuilder.dump(container);
+
+      expect(dump).toContain("xV4 Container Dump");
+      expect(dump).toContain("Frame count: 2");
+      expect(dump).toContain("frame_00001.");
+      expect(dump).toContain("frame_00002.");
+      expect(dump).toContain("360x360");
+    });
+  });
 });
diff --git a/src/lib/protocol/builders/xv4-header.ts b/src/lib/protocol/builders/xv4-header.ts
index 692e13d..58c3dd1 100644
--- a/src/lib/protocol/builders/xv4-header.ts
+++ b/src/lib/protocol/builders/xv4-header.ts
@@ -1,30 +1,39 @@
 /**
  * xV4 Animation header builder
  *
- * The xV4 format is a animation container
+ * The xV4 format is an animation container for BeamBox devices.
  *
  * ## Format Structure
  *
  * ```
- * [Magic: "xV4"] [3 bytes]
- * [Version] [1 byte] - Always 0x12
- * [Unknown] [1 byte] - Always 0x48
- * [Padding] [3 bytes] - Always 0x00 0x00 0x00
- * [Frame count] [4 bytes, LE u32]
- * [Total JPEG size] [4 bytes, LE u32] - Sum of all frame data sizes
- * [Timing string] [variable, null-terminated] - e.g., "output/50ms\0"
- * [Frame data offset] [4 bytes, LE u32] - Offset to where JPEG data starts
- * [Frame table] [variable] - Frame entries (name + size)
- * [Footer] [16 bytes] - Frame sizes (first 2), unknown, dimensions
- * [JPEG data] [variable] - Concatenated JPEG frames
+ * HEADER (32 bytes fixed):
+ * [0-3]   "xV4" + 0x12 (signature + version)
+ * [4-7]   Header size = frame_table_end - 8 (uint32 LE)
+ * [8-11]  Frame count (uint32 LE)
+ * [12-15] Unknown value = frame_count * 10 + 10 (uint32 LE)
+ * [16-27] Timing string "output/XXms\0" (12 bytes, null-padded)
+ * [28-31] Total data size including per-frame metadata (uint32 LE)
+ *
+ * FRAME TABLE (frame_count * 16 bytes):
+ * Each entry (16 bytes):
+ *   [0-11]  Frame name "frame_XXXXX." (12 bytes, dot-terminated)
+ *   [12-15] Cumulative offset from frame_table_end (uint32 LE)
+ *           This points to the per-frame metadata block, not the JPEG directly
+ *
+ * PER-FRAME DATA (repeated for each frame):
+ *   FRAME METADATA (32 bytes):
+ *   [0-3]   Current frame table offset (uint32 LE)
+ *   [4-7]   Next frame table offset (uint32 LE)
+ *           Points to next frame's metadata, or back to first frame for looping
+ *   [8-11]  Unknown value = frame_count - 3 (uint32 LE)
+ *   [12-13] Width (uint16 LE)
+ *   [14-15] Height (uint16 LE)
+ *   [16-19] Actual JPEG start offset in file (uint32 LE)
+ *   [20-23] Current frame JPEG size (uint32 LE)
+ *   [24-31] Padding zeros (8 bytes)
+ *
+ *   JPEG DATA (variable size)
  * ```
- *
- * ## Frame Table Entry
- *
- * Each entry consists of:
- * - Frame name (dot-terminated string): e.g., "frame_00001."
- * - Frame size (4 bytes, LE u32): Size of this JPEG frame in bytes
- *
  */
 
 export interface XV4Frame {
@@ -37,155 +46,196 @@ export interface XV4Frame {
 export class XV4HeaderBuilder {
   private static readonly SIGNATURE = Buffer.from("xV4");
   private static readonly VERSION = 0x12;
-  private static readonly UNKNOWN_BYTE = 0x48;
+
+  // Fixed sizes
+  private static readonly FIXED_HEADER_SIZE = 32;
+  private static readonly FRAME_ENTRY_SIZE = 16;
+  private static readonly FRAME_NAME_SIZE = 12;
+  private static readonly FRAME_METADATA_SIZE = 32;
 
   /**
    * Build complete xV4 animation container with frames
    *
    * @param frames Array of frames with names and JPEG data
    * @param intervalMs Frame interval in milliseconds (e.g., 50 for 20fps)
-   * @param width Image width (default: 368)
-   * @param height Image height (default: 368)
+   * @param width Image width (default: 360)
+   * @param height Image height (default: 360)
    * @returns Complete xV4 animation buffer ready to send
    */
   static build(
     frames: XV4Frame[],
     intervalMs: number = 50,
-    width: number = 368,
-    height: number = 368,
+    width: number = 360,
+    height: number = 360,
   ): Buffer {
     if (frames.length === 0) {
       throw new Error("At least one frame is required");
     }
 
-    // Calculate frame count
     const frameCount = frames.length;
 
-    // Total JPEG size field is it's frame_count * 1000
-    const totalSizeField = frameCount * 1000;
+    // Calculate sizes
+    const frameTableSize = frameCount * this.FRAME_ENTRY_SIZE;
+    const frameTableEnd = this.FIXED_HEADER_SIZE + frameTableSize;
 
-    const totalJpegSize = frames.reduce(
-      (sum, frame) => sum + frame.data.length,
+    // Total size = header + frame_table + (metadata + jpeg) for each frame
+    const totalDataSize = frames.reduce(
+      (sum, frame) => sum + this.FRAME_METADATA_SIZE + frame.data.length,
       0,
     );
-
-    // Build timing string with null terminator
-    const timingStr = `output/${intervalMs}ms`;
-    const timingBuffer = Buffer.from(timingStr + "\0", "utf-8");
-
-    // Calculate frame table size (each entry: name + "." + 4-byte size)
-    let frameTableSize = 0;
-    for (const frame of frames) {
-      frameTableSize += Buffer.from(frame.name + ".", "utf-8").length + 4;
-    }
-
-    // Footer size (from capture: 2 frame sizes + unknown + dimensions)
-    const footerSize = 16;
-
-    // Header structure:
-    const headerSize =
-      3 + // signature "xV4"
-      1 + // version 0x12
-      1 + // unknown 0x48
-      3 + // padding 0x00 0x00 0x00
-      4 + // frame count (u32 LE)
-      4 + // total JPEG size (u32 LE)
-      timingBuffer.length + // timing string with null terminator
-      4; // frame data offset (u32 LE)
-
-    // Frame data offset
-    const frameDataOffsetValue = 0x2c000 + (headerSize - 8);
-
-    // Actual container size: header + frame table + footer + JPEG data
-    // (We don't actually pad to frameDataOffsetValue in our container)
-    const actualDataOffset = headerSize + frameTableSize + footerSize;
-    const totalSize = actualDataOffset + totalJpegSize;
+    const totalSize = frameTableEnd + totalDataSize;
 
     const container = Buffer.alloc(totalSize);
     let offset = 0;
 
-    // Write signature "xV4"
+    // ===== HEADER (32 bytes) =====
+
+    // [0-2] Signature "xV4"
     this.SIGNATURE.copy(container, offset);
     offset += 3;
 
-    // Write version 0x12
+    // [3] Version 0x12
     container.writeUInt8(this.VERSION, offset);
     offset += 1;
 
-    // Write unknown byte 0x48
-    container.writeUInt8(this.UNKNOWN_BYTE, offset);
-    offset += 1;
+    // [4-7] Header size = frame_table_end - 8
+    const headerSizeField = frameTableEnd - 8;
+    container.writeUInt32LE(headerSizeField, offset);
+    offset += 4;
 
-    // Write padding (3 null bytes)
-    container.writeUInt8(0x00, offset);
-    offset += 1;
-    container.writeUInt8(0x00, offset);
-    offset += 1;
-    container.writeUInt8(0x00, offset);
-    offset += 1;
-
-    // Write frame count (u32 LE)
+    // [8-11] Frame count
     container.writeUInt32LE(frameCount, offset);
     offset += 4;
 
-    // Write total size field (u32 LE) - this is frame_count * 1000
-    container.writeUInt32LE(totalSizeField, offset);
+    // [12-15] Unknown value = frame_count * 10 + 10
+    const unknownValue = frameCount * 10 + 10;
+    container.writeUInt32LE(unknownValue, offset);
     offset += 4;
 
-    // Write timing string (null-terminated) - no null byte before it!
+    // [16-27] Timing string "output/XXms\0" (12 bytes, null-padded)
+    // The timing string must fit in 12 bytes including null terminator.
+    // This means intervals must be 10-99ms (2 digits) to fit "output/XXms\0" format.
+    // Clamp intervals to 50-99 range to ensure proper format.
+    const clampedInterval = Math.max(50, Math.min(99, intervalMs));
+    const timingStr = `output/${clampedInterval}ms`;
+    const timingBuffer = Buffer.alloc(this.FRAME_NAME_SIZE);
+    Buffer.from(timingStr, "utf-8").copy(timingBuffer);
+    // Add null terminator (rest is already zeros from alloc)
     timingBuffer.copy(container, offset);
-    offset += timingBuffer.length;
+    offset += this.FRAME_NAME_SIZE;
 
-    // Write frame data offset (u32 LE) - this is a reference value, not actual offset in our buffer
-    container.writeUInt32LE(frameDataOffsetValue, offset);
+    // [28-31] Total data size (metadata + jpeg for all frames)
+    container.writeUInt32LE(totalDataSize, offset);
     offset += 4;
 
-    // Write frame table
-    for (const frame of frames) {
-      // Write frame name with trailing dot (no null terminator)
-      const nameBuffer = Buffer.from(frame.name + ".", "utf-8");
-      nameBuffer.copy(container, offset);
-      offset += nameBuffer.length;
-
-      // Write frame size (u32 LE)
-      container.writeUInt32LE(frame.data.length, offset);
-      offset += 4;
-    }
-
-    // Write footer (16 bytes)
-    // First frame size
-    container.writeUInt32LE(frames[0]?.data.length || 0, offset);
-    offset += 4;
-
-    // Second frame size (or first if only one frame)
-    container.writeUInt32LE(
-      frames[1]?.data.length || frames[0]?.data.length || 0,
-      offset,
-    );
-    offset += 4;
-
-    // Unknown value (from capture: seems to be related to header size)
-    // In capture it was 0x0b (11) for 3 frames
-    container.writeUInt32LE(frameCount + 8, offset);
-    offset += 4;
-
-    // Dimensions (u16 LE + u16 LE)
-    container.writeUInt16LE(width, offset);
-    offset += 2;
-    container.writeUInt16LE(height, offset);
-    offset += 2;
-
-    // Now offset should be at actualDataOffset (where JPEG data actually starts in our buffer)
-    if (offset !== actualDataOffset) {
+    // Verify we're at the right position
+    if (offset !== this.FIXED_HEADER_SIZE) {
       throw new Error(
-        `Frame data offset calculation error: expected ${actualDataOffset}, got ${offset}`,
+        `Header size mismatch: expected ${this.FIXED_HEADER_SIZE}, got ${offset}`,
       );
     }
 
-    // Write JPEG data
-    for (const frame of frames) {
+    // ===== FRAME TABLE (frameCount * 16 bytes) =====
+
+    // Calculate cumulative offsets (metadata + jpeg for each frame)
+    // The offset stored is: frame_table_end + cumulative_offset_to_metadata
+    const frameTableOffsets: number[] = [];
+    let cumulativeOffset = 0;
+
+    for (let i = 0; i < frames.length; i++) {
+      const frame = frames[i]!;
+
+      // [0-11] Frame name (12 bytes, dot-terminated, null-padded)
+      const nameWithDot = frame.name + ".";
+      const nameBuffer = Buffer.alloc(this.FRAME_NAME_SIZE);
+      Buffer.from(nameWithDot, "utf-8").copy(
+        nameBuffer,
+        0,
+        0,
+        this.FRAME_NAME_SIZE,
+      );
+      nameBuffer.copy(container, offset);
+      offset += this.FRAME_NAME_SIZE;
+
+      // [12-15] Offset = frame_table_end + cumulative offset to this frame's metadata
+      const frameOffset = frameTableEnd + cumulativeOffset;
+      frameTableOffsets.push(frameOffset);
+      container.writeUInt32LE(frameOffset, offset);
+      offset += 4;
+
+      // Update cumulative offset for next frame (metadata + jpeg size)
+      cumulativeOffset += this.FRAME_METADATA_SIZE + frame.data.length;
+    }
+
+    // Verify frame table end position
+    if (offset !== frameTableEnd) {
+      throw new Error(
+        `Frame table end mismatch: expected ${frameTableEnd}, got ${offset}`,
+      );
+    }
+
+    // ===== PER-FRAME DATA (metadata + jpeg for each frame) =====
+
+    // TODO: Investigate unknown metadata field meaning
+    const unknownMetaValue = Math.max(0, frameCount - 3); // 11 for 14 frames?
+
+    for (let i = 0; i < frames.length; i++) {
+      const frame = frames[i]!;
+      const frameSize = frame.data.length;
+
+      // Current frame's table offset
+      const currentTableOffset = frameTableOffsets[i]!;
+      // Next frame's table offset (loop back to first frame for continuous playback)
+      const nextTableOffset =
+        i < frames.length - 1
+          ? frameTableOffsets[i + 1]!
+          : frameTableOffsets[0]!;
+      // Actual JPEG start position in file
+      const jpegStartOffset = offset + this.FRAME_METADATA_SIZE;
+
+      // ===== FRAME METADATA (32 bytes) =====
+
+      // [0-3] Current frame table offset
+      container.writeUInt32LE(currentTableOffset, offset);
+      offset += 4;
+
+      // [4-7] Next frame table offset (loops back to first frame for continuous playback)
+      container.writeUInt32LE(nextTableOffset, offset);
+      offset += 4;
+
+      // [8-11] Unknown value = frame_count - 3
+      container.writeUInt32LE(unknownMetaValue, offset);
+      offset += 4;
+
+      // [12-13] Width (uint16 LE)
+      container.writeUInt16LE(width, offset);
+      offset += 2;
+
+      // [14-15] Height (uint16 LE)
+      container.writeUInt16LE(height, offset);
+      offset += 2;
+
+      // [16-19] Actual JPEG start offset in file
+      container.writeUInt32LE(jpegStartOffset, offset);
+      offset += 4;
+
+      // [20-23] Current frame JPEG size
+      container.writeUInt32LE(frameSize, offset);
+      offset += 4;
+
+      // [24-31] Padding zeros (already zeroed from alloc)
+      offset += 8;
+
+      // ===== FRAME JPEG DATA =====
       frame.data.copy(container, offset);
-      offset += frame.data.length;
+      offset += frameSize;
+    }
+
+    // Verify final size
+    if (offset !== totalSize) {
+      throw new Error(
+        `Total size mismatch: expected ${totalSize}, got ${offset}`,
+      );
     }
 
     return container;
@@ -197,7 +247,7 @@ export class XV4HeaderBuilder {
    * @returns True if valid xV4 container
    */
   static validate(buffer: Buffer): boolean {
-    if (buffer.length < 20) {
+    if (buffer.length < this.FIXED_HEADER_SIZE) {
       return false;
     }
 
@@ -211,11 +261,79 @@ export class XV4HeaderBuilder {
       return false;
     }
 
-    // Check unknown byte
-    if (buffer.readUInt8(4) !== this.UNKNOWN_BYTE) {
-      return false;
-    }
-
     return true;
   }
+
+  /**
+   * Debug helper: dump xV4 container structure
+   */
+  static dump(buffer: Buffer): string {
+    const lines: string[] = [];
+    lines.push("=== xV4 Container Dump ===");
+
+    if (!this.validate(buffer)) {
+      lines.push("Invalid xV4 container");
+      return lines.join("\n");
+    }
+
+    lines.push(`Total size: ${buffer.length} bytes`);
+    lines.push("");
+
+    // Header
+    lines.push("HEADER:");
+    lines.push(`  Signature: ${buffer.subarray(0, 3).toString()}`);
+    lines.push(`  Version: 0x${buffer.readUInt8(3).toString(16)}`);
+    lines.push(`  Header size field: ${buffer.readUInt32LE(4)}`);
+    lines.push(`  Frame count: ${buffer.readUInt32LE(8)}`);
+    lines.push(`  Unknown field: ${buffer.readUInt32LE(12)}`);
+
+    const timingStr = buffer
+      .subarray(16, 28)
+      .toString("utf-8")
+      .replace(/\0.*$/, "");
+    lines.push(`  Timing string: "${timingStr}"`);
+    lines.push(`  Total JPEG size: ${buffer.readUInt32LE(28)}`);
+
+    // Frame table
+    const frameCount = buffer.readUInt32LE(8);
+    lines.push("");
+    lines.push(`FRAME TABLE (${frameCount} entries):`);
+
+    let tableOffset = this.FIXED_HEADER_SIZE;
+    for (let i = 0; i < frameCount && tableOffset + 16 <= buffer.length; i++) {
+      const name = buffer
+        .subarray(tableOffset, tableOffset + 12)
+        .toString("utf-8")
+        .replace(/\0.*$/, "");
+      const cumOffset = buffer.readUInt32LE(tableOffset + 12);
+      lines.push(`  [${i}] name="${name}", cumOffset=${cumOffset}`);
+      tableOffset += 16;
+    }
+
+    // First frame metadata (32 bytes)
+    const firstMetadataStart =
+      this.FIXED_HEADER_SIZE + frameCount * this.FRAME_ENTRY_SIZE;
+    if (firstMetadataStart + this.FRAME_METADATA_SIZE <= buffer.length) {
+      lines.push("");
+      lines.push("FIRST FRAME METADATA:");
+      lines.push(
+        `  Current table offset: ${buffer.readUInt32LE(firstMetadataStart)}`,
+      );
+      lines.push(
+        `  Next table offset: ${buffer.readUInt32LE(firstMetadataStart + 4)}`,
+      );
+      lines.push(`  Unknown: ${buffer.readUInt32LE(firstMetadataStart + 8)}`);
+      lines.push(
+        `  Dimensions: ${buffer.readUInt16LE(firstMetadataStart + 12)}x${buffer.readUInt16LE(firstMetadataStart + 14)}`,
+      );
+      lines.push(
+        `  JPEG offset: ${buffer.readUInt32LE(firstMetadataStart + 16)}`,
+      );
+      lines.push(
+        `  Frame size: ${buffer.readUInt32LE(firstMetadataStart + 20)}`,
+      );
+    }
+
+    return lines.join("\n");
+  }
 }
diff --git a/src/lib/protocol/interfaces/config.ts b/src/lib/protocol/interfaces/config.ts
index 263082d..7db2b82 100644
--- a/src/lib/protocol/interfaces/config.ts
+++ b/src/lib/protocol/interfaces/config.ts
@@ -86,6 +86,13 @@ export interface ImageConfig {
    */
   defaultSize: [number, number];
 
+  /**
+   * Default frame dimensions [width, height] for animations
+   *
+   * Frames are resized to fit these dimensions
+   */
+  animationsSize: [number, number];
+
   /**
    * JPEG compression quality (0-100)
    *
diff --git a/src/lib/protocol/interfaces/defaults.ts b/src/lib/protocol/interfaces/defaults.ts
index f71b800..96197f0 100644
--- a/src/lib/protocol/interfaces/defaults.ts
+++ b/src/lib/protocol/interfaces/defaults.ts
@@ -40,16 +40,18 @@ export const DEFAULT_PROTOCOL_CONFIG: ProtocolConfig = {
 /**
  * Default image processing configuration
  *
- * Standard settings for processing images for the 368x368 BeamBox display.
+ * Standard settings for processing images for the BeamBox display.
  *
- * - defaultSize: [368, 368] - device native resolution
- * - jpegQuality: 70 - good balance between quality and size
+ * - defaultSize: [368, 368] - device native resolution for static images
+ * - animationsSize: [360, 360] - frame resolution for animations (Type 5)
+ * - jpegQuality: 80 - quality for static images (animations use 75)
  * - jpegOptimize: true - enable optimization for smaller files
  * - checkerboardSquares: 8 - for test pattern generation
  */
 export const DEFAULT_IMAGE_CONFIG: ImageConfig = {
   defaultSize: [368, 368],
-  jpegQuality: 70,
+  animationsSize: [360, 360],
+  jpegQuality: 80,
   jpegOptimize: true,
   checkerboardSquares: 8,
 };
diff --git a/src/lib/protocol/interfaces/device-status.ts b/src/lib/protocol/interfaces/device-status.ts
index e23c7e8..ed173f3 100644
--- a/src/lib/protocol/interfaces/device-status.ts
+++ b/src/lib/protocol/interfaces/device-status.ts
@@ -27,7 +27,7 @@ export interface DeviceStatus {
   /**
    * Display resolution as "width,height" string
    *
-   * Example: "368,368" = 368x368 pixels
+   * Example: "368,368" = 368x368 pixels (static); animations use 360x360
    */
   size: string;
 
diff --git a/src/lib/protocol/packet-types.ts b/src/lib/protocol/packet-types.ts
index 65cb295..96c60d1 100644
--- a/src/lib/protocol/packet-types.ts
+++ b/src/lib/protocol/packet-types.ts
@@ -16,7 +16,7 @@ export enum PacketType {
   /**
    * 0x05: DYNAMIC_AMBIENCE (Client to Device)
    *
-   * Used for ALL animated content: videos, GIFs, and image gallery mode
+   * Used for ALL animated content: videos, GIFs, and image gallery mode.
    *
    * ## Upload Process (Two-Step)
    *
@@ -30,35 +30,27 @@ export enum PacketType {
    * {"type":5,"data":<xV4_ANIMATION_DATA>}
    * ```
    *
-   * ## Animation Data Format
+   * ## xV4 Animation Format
    *
-   * The data payload contains:
-   * TODO: Validate this format more thoroughly
-   * - Signature: "xV4" (0x78 0x56 0x34), custom animation format?
-   * - Frame timing: "output/50ms" interval between frames
-   * - Frame references: "frame_00001", "frame_00002", etc.
-   * - Multiple JPEG frames embedded in single payload
+   * The data payload is an xV4 container containing:
+   * - 32-byte header with signature "xV4" + version 0x12
+   * - Frame table with offsets to each frame's metadata
+   * - Per-frame data: 32-byte metadata + JPEG data
+   * - Looping: last frame's next_offset points back to first frame
    *
-   * ## How Content is Converted to Animation
+   * Frame requirements:
+   * - Size: 360x360 pixels
+   * - Format: JPEG with JFIF APP0 marker
+   * - Quality: 75
+   * - Chroma: 4:4:4 (no subsampling)
    *
-   * TODO: Implement using ffmpeg to extract frames and build xV4 format?
-   *
-   * ```bash
-   * # Get video info
-   * ffprobe -v quiet -show_entries format=duration -of csv=p=0 input.mp4
-   * ffprobe -v quiet -select_streams v:0 -show_entries stream=r_frame_rate -of csv=p=0 input.mp4
-   *
-   * # Extract frames
-   * ffmpeg -i input.mp4 output/frame_%05d.jpg
-   * ```
+   * For more information, go see xv4-header.ts
    *
    * ## Use Cases
    *
    * - Video upload: Extract frames from video file
    * - GIF upload: Separate animated GIF into frames
-   * - Gallery/slideshow Mode: Convert multiple images to animation with interval (the official app does this)
-   *
-   * TODO: Full implementation pending
+   * - Gallery/slideshow: Convert multiple images to animation with interval
    */
   DYNAMIC_AMBIENCE = 0x05,
 
@@ -73,37 +65,37 @@ export enum PacketType {
    * ```json
    * {"type":6,"number":1}
    * ```
-   * TODO: Validate if "number" means image count
-   * - Announces that 1 image is coming? (Always observed as 1, even for multiple images, so might be something else)
+   * - Announces that 1 image is coming
    * - Device responds with DEVICE_STATUS (type 13)
    *
    * Step 2 - Send image data:
    * ```
    * {"type":6,"data":<IMB_HEADER><JPEG_BINARY>}
    * ```
-   * - IMB header: 36 bytes (contains size, dimensions)
+   * - IMB header: 14 bytes (signature + size + dimensions + padding)
    * - JPEG data: Raw binary JPEG file
    * - Sent in chunks (0x1F0 (496) bytes per chunk)
    * - Device responds "GetPacketSuccess" for each chunk
    *
+   * ## Image Requirements from official app
+   *
+   * - Size: 368x368 pixels
+   * - Format: JPEG with JFIF APP0 marker
+   * - Quality: 80
+   * - Chroma: 4:2:0 subsampling
+   *
    * ## Important Notes
    * - For multiple images: repeat the 2-step process sequentially
-   * - For IMB header format, see IMBHeaderBuilder in src/lib/protocol/imb-header.ts
-   * - Gallery/slideshow mode on the official app does NOT use this, uses DYNAMIC_AMBIENCE (Type 5) and preprocessing instead
-   *
-   * The official app's "Image Gallery" feature works by:
-   * 1. Converting multiple images into animation using FFmpeg
-   * 2. Creating frame sequence: frame_00001.jpg, frame_00002.jpg, etc.
-   * 3. Sending as Type 5 (DYNAMIC_AMBIENCE) with embedded timing
-   *
+   * - For IMB header format, see IMBHeaderBuilder in imb-header.ts
+   * - Gallery/slideshow mode uses DYNAMIC_AMBIENCE (Type 5), not this
    */
   IMAGE = 0x06,
 
   /**
    * 0x0C: PHOTO_ALBUM_COUNT (Client to Device)
    *
-   * Would announce number of images in gallery/album mode??
-   * TODO: Does not seem to be used or might be used on another model, needs further investigation
+   * Would announce number of images in gallery/album mode.
+   * Not used in current implementation, may be for other models.
    */
   PHOTO_ALBUM_COUNT = 0x0c,
 
@@ -128,9 +120,8 @@ export enum PacketType {
    * ## When Sent
    *
    * Device sends this in response to:
-   * - Image info packet (Type)
+   * - Image info packet (Type 6)
    * - Used to check available storage before upload
-   *
    */
   DEVICE_STATUS = 0x0d,
 }
diff --git a/src/lib/protocol/parsers/response-parser.test.ts b/src/lib/protocol/parsers/response-parser.test.ts
index d69f776..96b7c59 100644
--- a/src/lib/protocol/parsers/response-parser.test.ts
+++ b/src/lib/protocol/parsers/response-parser.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect } from "bun:test";
+import { describe, test, expect } from "vitest";
 import { ResponseParser } from "./response-parser.ts";
 import { PacketType } from "../packet-types.ts";
 import { ResponseStatus } from "../response-types.ts";
diff --git a/src/lib/utils/errors.test.ts b/src/lib/utils/errors.test.ts
index 30b6117..086488c 100644
--- a/src/lib/utils/errors.test.ts
+++ b/src/lib/utils/errors.test.ts
@@ -1,4 +1,4 @@
-import { describe, test, expect } from "bun:test";
+import { describe, test, expect } from "vitest";
 import {
   BeamBoxError,
   DeviceNotFoundError,