MediaCodec崩潰

Question

我用下面的代碼(original guide)解碼H264視頻流：

public void configure(Surface surface, int width, int height, ByteBuffer csd0) { 
     String VIDEO_FORMAT = "video/avc"; 
     if (mConfigured) { 
      throw new IllegalStateException("Decoder is already configured"); 
     } 
     MediaFormat format = MediaFormat.createVideoFormat(VIDEO_FORMAT, width, height); 
     // little tricky here, csd-0 is required in order to configure the codec properly 
     // it is basically the first sample from encoder with flag: BUFFER_FLAG_CODEC_CONFIG 
     format.setByteBuffer("csd-0", csd0); 
     try { 
      mCodec = MediaCodec.createDecoderByType(VIDEO_FORMAT); 
     } catch (IOException e) { 
      throw new RuntimeException("Failed to create codec", e); 
     } 
     mCodec.configure(format, surface, null, 0); 
     mCodec.start(); 
     mConfigured = true; 
    } 

    @SuppressWarnings("deprecation") 
    public void decodeSample(byte[] data, int offset, int size, long presentationTimeUs, int flags) { 
     if (mConfigured && mRunning) { 
      int index = mCodec.dequeueInputBuffer(mTimeoutUs); 
      if (index >= 0) { 
       ByteBuffer buffer; 
       // since API 21 we have new API to use 
       if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) { 
        buffer = mCodec.getInputBuffers()[index]; 
        buffer.clear(); 
       } else { 
        buffer = mCodec.getInputBuffer(index); 
       } 
       if (buffer != null) { 
        buffer.put(data, offset, size); 
        mCodec.queueInputBuffer(index, 0, size, presentationTimeUs, flags); 
       } 
      } 
     } 
    } 

    @Override 
    public void run() { 
     try { 
      MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); 
      while (mRunning) { 
       if (mConfigured) { 
        int index = mCodec.dequeueOutputBuffer(info, mTimeoutUs); 
        if (index >= 0) { 
         // setting true is telling system to render frame onto Surface 
         mCodec.releaseOutputBuffer(index, true); 
         if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) == MediaCodec.BUFFER_FLAG_END_OF_STREAM) { 
          break; 
         } 
        } 
       } else { 
        // just waiting to be configured, then decode and render 
        try { 
         Thread.sleep(10); 
        } catch (InterruptedException ignore) { 
        } 
       } 
      } 
     } finally { 
      if (mConfigured) { 
       mCodec.stop(); 
       mCodec.release(); 
      } 
     } 
    } 

我可以同時在我的Nexus 6（API 22）和三星Galaxy核心運行這個（API 16）在低和中等質量。但是，當我切換到高質量（720p）時，在約30幀後它在三星上崩潰（但沒有任何東西呈現在屏幕上）。

E/ACodec﹕ [OMX.qcom.video.decoder.avc] ERROR(0x8000100a) 
E/MediaCodec﹕ Codec reported an error. (omx error 0x8000100a, internalError -2147483648) 
[...] 
W/System.err﹕ java.lang.IllegalStateException 
W/System.err﹕ at android.media.MediaCodec.dequeueInputBuffer(Native Method) 
W/System.err﹕ at com.test.stream.VideoDecoder$Worker.decodeSample(VideoDecoder.java:95) 
W/System.err﹕ at com.test.stream.VideoDecoder.decodeSample(VideoDecoder.java:24) 
W/System.err﹕ at com.test.stream.VideoThread.run(VideoThread.java:160) 

上面的錯誤是第一個出現的錯誤，IllegalStateException後來拋出每幀。

我的問題是，這是一個設備特定的問題（因爲：較舊的api /設備，較弱的功能等）還是實際上是錯的？ 以及我應該如何處理？

Answer 1

對於我的Android h.264解碼器，我將它與您的設置略有不同。我認爲你使用更現代化的api級別。但對我來說，它看起來更像是這樣的：

public void startDecoder() { 
    // Initilize codec 
    mediaCodec = MediaCodec.createDecoderByType("video/avc"); 
    mediaFormat = MediaFormat.createVideoFormat("video/avc", 0, 0); 
    bufferInfo = new MediaCodec.BufferInfo(); 

    // STOPS unit-tests from crashing here from mocked out android 
    if (mediaCodec != null) { 
     mediaCodec.configure(mediaFormat, targetSurface, null, 0); 
     mediaCodec.start(); 
     decoderThread = new Thread(this); 
     decoderThread.start(); 
    } 
} 

//解碼線程是指這個類確實解碼器/渲染循環：

public void run() { 
    //mediaCodec input + output dequeue timeouts 
    long kInputBufferTimeoutMs = 50; 
    long kOutputBufferTimeoutMs = 50; 

    while (running && mediaCodec != null) { 
     synchronized (mediaCodec) { 
      // stop if not running. 
      if (!running || mediaCodec == null) 
       break; 

      // Only push in new data if there is data available in the queue 
      if (naluSegmentQueue.size() > 0) { 
       int inputBufferIndex = mediaCodec.dequeueInputBuffer(kInputBufferTimeoutMs); 
       if (inputBufferIndex >= 0) { 
        NaluSegment segment = naluSegmentQueue.poll(); 
        codecInputBufferAvailable(segment, mediaCodec, inputBufferIndex); 
       } 
      } 

      // always check if output is available. 
      int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, kOutputBufferTimeoutMs); 
      if (outputBufferIndex >= 0) { 
       // Try and render first 
       codecOuputBufferAvailable(mediaCodec, outputBufferIndex, bufferInfo); 
      } else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) { 
       // Subsequent data will conform to new format. 
       // Can ignore if using getOutputFormat(outputBufferId) 
       mediaFormat = mediaCodec.getOutputFormat(); 
      } 
     } 
    } 
} 

將數據放入解碼器包括參數。我懶得試圖使用csd-0/1網絡流可以改變格式描述，並且更容易讓它動態獲取。

private void codecInputBufferAvailable(NaluSegment segment, MediaCodec codec, int index) { 
    int flags = (segment.getType() == NaluType.SPS 
      || segment.getType() == NaluType.PPS 
      || segment.getType() == NaluType.SUPP_ENHANCEMENT) ? 
      MediaCodec.BUFFER_FLAG_CODEC_CONFIG : MediaCodec.BUFFER_FLAG_SYNC_FRAME; 

    ByteBuffer[] buffers = codec.getInputBuffers(); 
    ByteBuffer buffer = buffers[index]; 
    // Can throw buffer overflow exception when buffer sizes are too small. 
    try { 
     buffer.put(segment.getBuffer()); 
     codec.queueInputBuffer(index, 0, segment.getBufferSize(), 0, flags); 
    } catch(Exception e) { 
     Log.e(TAG, "Failed to push buffer to decoder"); 
    } 
} 

重要：buffer.put（segment.getBuffer（））; getBuffer（）在這裏總是返回一個4字節的緩衝區。 android解碼器不理解3個字節的最終單位。所以如果你有一個3字節的nal單元，將它變成4字節的長度爲+1的魔術序列，並且0x00，0x00，0x00，0x01作爲啓動魔術序列，緩衝區的其餘部分應該是& buffer [headerLength]。

注意這裏的try-catch並沒有給出編譯器警告，但是如果你有一個非常大的有效負載和字節緩衝區太小，它可能會拋出緩衝區溢出異常。

只要你解析出你的NAL單位，這應該適合你。但對於我的情況，我注意到NAL單位可以是3或4個字節的魔頭。

/** 
* H264 is comprised of NALU segments. 
* 
* XXXX Y ZZZZZZZZ -> XXXX Y ZZZZZZZZ -> XXXX Y ZZZZZZZZ 
* 
* Each segment is comprised of: 
* 
* XXXX -> Magic byte header (0x00, 0x00, 0x00, 0x01) NOTE: this can be either 3 of 4 bytes 
* Y  -> The Nalu Type 
* ZZZ... -> The Payload 
* 
* Notice there is no nalu length specified. To parse an nalu, you must 
* read until the next magic-byte-sequence AKA the next segment to figure 
* out the full nalu length 
**/ 
public static List<NaluSegment> parseNaluSegments(byte[] buffer) throws NaluBufferException { 
    List<NaluSegment> segmentList = new ArrayList<>(); 
    if (buffer.length < 6) { 
     return segmentList; 
    } 

    int lastStartingOffset = -1; 
    for (int i = 0; i < buffer.length - 10; ++i) { 
     **if (buffer[i] == 0x00 && buffer[i+1] == 0x00 && buffer[i+2] == 0x01)** { 
      int naluType = (buffer[i+3] & 0x1F); 
      NaluSegment segment = new NaluSegment(naluType, 3, i); 

      **if (i > 0 && buffer[i-1] == 0x00)** { 
       // This is actually a 4 byte segment 
       int currentSegmentOffset = segment.getOffset(); 
       segment.setHeaderSize(4); 
       segment.setOffset(currentSegmentOffset - 1); 
      } 
... 

創建您自己的nalu段對象，並且不要忘記尾隨的NAL。

我希望這會有所幫助。