fix: HEVC description偏移修正(70→78)+调试日志

- findCodecConfig: VisualSampleEntry偏移从70改为78字节（ISO 14496-12）
- extractCodecDescription: 添加调试日志（moovOffset/moovSize/searchRange/found/resultByteLength）
- findCodecConfig: 添加stsd和entry的调试日志（entryCount/entryOffset/entrySize/entryType）

apps/web/src/pages/generate/hooks/useCanvasPlayer.ts

@@ -36,15 +36,27 @@ function findCodecConfig(buffer: ArrayBuffer, start: number, end: number): Array
       // SampleDescriptionBox 是 fullbox: 8 header + 4 version/flags + 4 entry_count
       const entryCount = view.getUint32(offset + 12)
       let entryOffset = offset + 16
+      console.log("[findCodecConfig] stsd found:", {
+        entryCount,
+        stsdOffset: offset,
+        stsdSize: size,
+      })
       for (let i = 0; i < entryCount && entryOffset < offset + size; i++) {
         const entrySize = view.getUint32(entryOffset)
+        const entryType = String.fromCharCode(
+          view.getUint8(entryOffset + 4),
+          view.getUint8(entryOffset + 5),
+          view.getUint8(entryOffset + 6),
+          view.getUint8(entryOffset + 7),
+        )
+        console.log("[findCodecConfig] entry:", { index: i, entryOffset, entrySize, entryType })
         // 视觉样本条目: 8 header + 6 reserved + 2 data_ref_index + remaining
         // 子 box 从 entryOffset + 16 + 62 开始 (skip reserved + data_ref_index + predefined)
         // 实际结构: 8(header) + 6(reserved) + 2(data_ref_index) + 16(predefined+reserved) + 2(width) + 2(height) + ...
         // 子 box 从 entryOffset + 8 + 6 + 2 + 16 + 2 + 2 + 2 + 2 + 4 + 2 + 2 + 2 + 2 = entryOffset + 78
         // 更简单的做法：扫描 entry 内的子 box
         const entryEnd = entryOffset + entrySize
-        const subBoxStart = entryOffset + 8 + 70 // VisualSampleEntry 固定字段共 70 字节
+        const subBoxStart = entryOffset + 8 + 78 // VisualSampleEntry 固定字段共 78 字节（ISO 14496-12）
         const result = findCodecConfig(buffer, subBoxStart, entryEnd)
         if (result) return result
         entryOffset += entrySize
@@ -136,6 +148,8 @@ interface SegmentMeta {
   videoHeight: number
   /** 解码器配置数据（HEVC hvcC / H.264 avcC），WebCodecs 必需 */
   description?: ArrayBuffer
+  /** 前端提取的样本数据（已按时间范围过滤，从关键帧开始） */
+  samples: Sample[]
 }
 
 // ── 播放器状态 ──
@@ -244,7 +258,15 @@ export function useCanvasPlayer(
           view.getUint8(offset + 7),
         )
         if (type === "moov") {
-          return findCodecConfig(buffer, offset + 8, offset + size)
+          const result = findCodecConfig(buffer, offset + 8, offset + size)
+          console.log("[useCanvasPlayer] extractCodecDescription:", {
+            moovOffset: offset,
+            moovSize: size,
+            searchRange: [offset + 8, offset + size],
+            found: !!result,
+            resultByteLength: result?.byteLength,
+          })
+          return result
         }
         if (size === 0) break
         offset += size
@@ -255,11 +277,15 @@ export function useCanvasPlayer(
     return undefined
   }, [])
 
-  // ── 解封装单个片段，提取轨道元数据 ──
+  // ── 解封装单个片段，提取轨道元数据 + 按时间范围过滤样本 ──
+  // ✅ 关键修复：改为异步函数，等待 MP4Box.js 的 onSamples 回调完成后再返回
   const demuxSegment = useCallback(
-    (buffer: ArrayBuffer, segIndex: number): SegmentMeta | null => {
-      const segment = segments[segIndex]
-      if (!segment) return null
+    async (buffer: ArrayBuffer, segIndex: number): Promise<SegmentMeta | null> => {
+      const segment = segments?.[segIndex]
+      if (!segment) {
+        console.warn("[useCanvasPlayer] No segment at index", segIndex)
+        return null
+      }
 
       // 计算全局偏移
       let globalStart = 0
@@ -268,72 +294,164 @@ export function useCanvasPlayer(
       }
 
       const mp4File = createFile()
-      let meta: SegmentMeta | null = null
 
-      mp4File.onReady = (info: Movie) => {
-        const videoTrack = info.videoTracks[0]
-        if (!videoTrack) {
-          console.error("[useCanvasPlayer] No video track found for segment", segIndex)
-          return
-        }
+      return new Promise<SegmentMeta | null>((resolve) => {
+        let meta: SegmentMeta | null = null
+        let resolved = false
 
-        // 提取编解码器配置数据（HEVC 必需，H.264 也需要）
-        let description = extractCodecDescription(buffer)
-
-        // 如果当前分片没有 description，尝试从缓存获取（后续分片可能不含 moov box）
-        if (!description) {
-          for (const cached of descriptionCache.current.values()) {
-            description = cached
-            break
+        // ✅ 超时保护：5秒后如果 onSamples 没有触发，返回 null
+        const timeout = setTimeout(() => {
+          if (!resolved) {
+            console.error(
+              `[useCanvasPlayer] Timeout: onSamples not triggered for segment ${segIndex}`,
+            )
+            resolved = true
+            resolve(null)
           }
-        }
+        }, 5000)
 
-        // 如果找到了 description，缓存起来供后续分片使用
-        if (description) {
+        mp4File.onReady = (info: Movie) => {
+          const videoTrack = info?.videoTracks?.[0]
+
+          console.log("[useCanvasPlayer] demuxSegment:", {
+            segIndex,
+            startTime: segment.startTime,
+            endTime: segment.endTime,
+            nbSamples: videoTrack?.nb_samples,
+            codec: videoTrack?.codec,
+            videoWidth: videoTrack?.track_width,
+            videoHeight: videoTrack?.track_height,
+          })
+
+          if (!videoTrack) {
+            console.warn("[useCanvasPlayer] No video track found for segment", segIndex)
+            clearTimeout(timeout)
+            resolved = true
+            resolve(null)
+            return
+          }
+
+          // 提取编解码器配置数据（HEVC 必需，H.264 也需要）
+          let description = extractCodecDescription(buffer)
+
+          // 如果当前分片没有 description，尝试从缓存获取
+          if (!description) {
+            for (const cached of descriptionCache.current.values()) {
+              description = cached
+              break
+            }
+          }
+
+          // ✅ 如果 description 缺失，无法解码 HEVC
+          if (!description) {
+            console.error(
+              `[useCanvasPlayer] No description found for segment ${segIndex}, cannot decode HEVC`,
+            )
+            clearTimeout(timeout)
+            resolved = true
+            resolve(null)
+            return
+          }
+
+          // 缓存 description 供后续分片使用
           descriptionCache.current.set(segment.assetId, description)
+
+          meta = {
+            assetId: segment.assetId,
+            videoUrl: segment.videoUrl,
+            globalStartTime: globalStart,
+            globalEndTime: globalStart + (segment.endTime - segment.startTime),
+            trackId: videoTrack.id ?? 1,
+            timescale: videoTrack.timescale ?? 90000,
+            codec: videoTrack.codec ?? "avc1.42E01E",
+            videoWidth: videoTrack.track_width || 1280,
+            videoHeight: videoTrack.track_height || 720,
+            description,
+            samples: [],
+          }
+
+          // 提取所有 samples
+          mp4File.setExtractionOptions(videoTrack.id ?? 1, null, {
+            nbSamples: Infinity, // 提取所有 sample
+          })
+          mp4File.start()
         }
 
-        meta = {
-          assetId: segment.assetId,
-          videoUrl: segment.videoUrl,
-          globalStartTime: globalStart,
-          globalEndTime: globalStart + (segment.endTime - segment.startTime),
-          trackId: videoTrack.id,
-          timescale: videoTrack.timescale,
-          codec: videoTrack.codec,
-          videoWidth: videoTrack.track_width || 1280,
-          videoHeight: videoTrack.track_height || 720,
-          description,
+        mp4File.onSamples = (_trackId: number, _user: unknown, samples: Sample[]) => {
+          if (resolved) return // ✅ 防止重复 resolve
+
+          if (!meta) {
+            clearTimeout(timeout)
+            resolved = true
+            resolve(null)
+            return
+          }
+
+          // 前端切片：按 [startTime, endTime] 时间范围过滤样本
+          const timescale = meta.timescale
+          const startCts = segment.startTime * timescale
+          const endCts = segment.endTime * timescale
+
+          // 过滤出时间范围内的样本
+          let filtered = samples.filter((s) => (s?.cts ?? 0) >= startCts && (s?.cts ?? 0) < endCts)
+
+          // 确保从关键帧开始（跳过第一个 sync 之前的非关键帧）
+          let foundSync = false
+          filtered = filtered.filter((s) => {
+            if (s.is_sync) {
+              foundSync = true
+              return true
+            }
+            return foundSync
+          })
+
+          // Fallback：如果时间范围内没有样本，使用全部样本从第一个关键帧开始
+          if (filtered.length === 0) {
+            console.warn(
+              `[useCanvasPlayer] No samples in range [${segment.startTime}s, ${segment.endTime}s] for segment ${segIndex}, fallback to all from keyframe`,
+            )
+            let sync = false
+            filtered = samples.filter((s) => {
+              if (s.is_sync) {
+                sync = true
+                return true
+              }
+              return sync
+            })
+          }
+
+          meta.samples = filtered
+          console.log(
+            `[useCanvasPlayer] Segment ${segIndex}: ${filtered.length}/${samples.length} samples (range ${segment.startTime}s-${segment.endTime}s)`,
+          )
+
+          // ✅ 关键修复：等待 onSamples 完成后再返回
+          clearTimeout(timeout)
+          resolved = true
+          resolve(meta)
         }
 
-        // 提取所有 samples（start() 会同步触发 onSamples）
-        mp4File.setExtractionOptions(videoTrack.id, null, {
-          nbSamples: videoTrack.nb_samples,
-        })
-        mp4File.start()
-      }
+        mp4File.onError = (_module: string, message: string) => {
+          console.error(`[useCanvasPlayer] MP4Box error: ${message}`)
+          clearTimeout(timeout)
+          resolved = true
+          resolve(null)
+        }
 
-      mp4File.onError = (_module: string, message: string) => {
-        console.error(`[useCanvasPlayer] MP4Box error: ${message}`)
-      }
-
-      // mp4box 需要在 buffer 上设置 fileStart 属性
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      ;(buffer as any).fileStart = 0
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      mp4File.appendBuffer(buffer as any)
-
-      return meta
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        ;(buffer as any).fileStart = 0
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        mp4File.appendBuffer(buffer as any)
+      })
     },
     [segments, extractCodecDescription],
   )
 
   // ── 初始化 VideoDecoder 并解码指定片段 ──
   const decodeSegment = useCallback(
-    async (buffer: ArrayBuffer, meta: SegmentMeta): Promise<void> => {
+    async (_buffer: ArrayBuffer, meta: SegmentMeta): Promise<void> => {
       if (isDestroyedRef.current) return
 
-      const mp4File = createFile()
       let decoderReady = false
 
       // 配置解码器（每个片段可能需要不同的 codec/分辨率）
@@ -381,51 +499,23 @@ export function useCanvasPlayer(
 
       if (!decoderReady) return
 
-      // 收集 samples
-      const samplesCollected: Sample[] = []
-
-      mp4File.onReady = (info: Movie) => {
-        const videoTrack = info.videoTracks[0]
-        if (!videoTrack) return
-
-        mp4File.setExtractionOptions(videoTrack.id, null, {
-          nbSamples: videoTrack.nb_samples,
-        })
-        mp4File.start()
+      // 使用 demuxSegment 中已提取并过滤的 samples（前端切片）
+      const samplesCollected = meta.samples
+      if (samplesCollected.length === 0) {
+        console.warn("[useCanvasPlayer] No samples to decode for segment", meta.assetId)
+        return
       }
 
-      mp4File.onSamples = (_trackId: number, _user: unknown, samples: Sample[]) => {
-        samplesCollected.push(...samples)
-      }
-
-      mp4File.onError = (_module: string, message: string) => {
-        console.error(`[useCanvasPlayer] MP4Box decode error: ${message}`)
-      }
-
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      ;(buffer as any).fileStart = 0
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      mp4File.appendBuffer(buffer as any)
-
-      // 等待 samples 收集完成（mp4box start() 是同步的）
-      await new Promise((resolve) => setTimeout(resolve, 10))
-
-      // 送入解码器（跳过第一个关键帧之前的非关键帧）
-      let hasKeyFrame = false
+      // 送入解码器
       for (const sample of samplesCollected) {
         if (!sample.data || isDestroyedRef.current) continue
         if (decoder.state === "closed") break
 
-        if (!hasKeyFrame && !sample.is_sync) {
-          console.warn("[useCanvasPlayer] Skipping non-keyframe chunk before first sync")
-          continue
-        }
-        if (sample.is_sync) hasKeyFrame = true
-
+        if (!sample.data) continue
         const chunk = new EncodedVideoChunk({
           type: sample.is_sync ? "key" : "delta",
-          timestamp: (sample.cts / meta.timescale) * 1_000_000,
-          duration: (sample.duration / meta.timescale) * 1_000_000,
+          timestamp: ((sample.cts ?? 0) / (meta.timescale || 90000)) * 1_000_000,
+          duration: ((sample.duration ?? 0) / (meta.timescale || 90000)) * 1_000_000,
           data: sample.data,
         })
 
@@ -648,12 +738,12 @@ export function useCanvasPlayer(
 
       if (isDestroyedRef.current) return
 
-      // 2. 解析每个片段的轨道元数据
+      // 2. 解析每个片段的轨道元数据（await 等待 onSamples 回调完成）
       const metas: SegmentMeta[] = []
       for (let i = 0; i < segments.length; i++) {
         const buffer = segmentDataRef.current.get(segments[i].assetId)
         if (!buffer) continue
-        const meta = demuxSegment(buffer, i)
+        const meta = await demuxSegment(buffer, i)
         if (meta) metas.push(meta)
       }