MediaCodec.jpg

MediaCodec 的整體流程如上圖所示，從input 輸入數(shù)據(jù)猫胁，從output 輸出數(shù)據(jù)维咸。解碼的時候輸入的是壓縮數(shù)據(jù)，輸出的是解碼后的原始數(shù)據(jù)狐肢。

初始化

如果傳入了 Surface添吗，那么解碼完的數(shù)據(jù)可以直接渲染到 Surface 上。

public void startDecode(MediaFormat format, SurfaceView surfaceView) {
    Surface surface = surfaceView.getHolder().getSurface();
    mFormat = format;
    final String mimeType = format.getString(MediaFormat.KEY_MIME);

    // Check to see if this is actually a video mime type. If it is, then create
    // a codec that can decode this mime type.
    try {
        mCodec = MediaCodec.createDecoderByType(mimeType);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
    mCodec.configure(format,surface, null, 0);
    mCodec.start();
}

寫數(shù)據(jù)

將壓縮的數(shù)據(jù)送入解碼器份名。

public void sendPackage(VEAVPacket packet) {
    int size = packet.buffer.capacity();
    int inputBufferId = mCodec.dequeueInputBuffer(timeOut);
    if (inputBufferId >= 0) {
        // fill inputBuffers[inputBufferId] with valid data
        ByteBuffer buffer = mCodec.getInputBuffer(inputBufferId);
        buffer.put(packet.buffer);
        mCodec.queueInputBuffer(inputBufferId, 0, size, packet.dts, packet.flag);
    }
}

取數(shù)據(jù)

如果不直接渲染到 Surface 上碟联，我們也可以把解壓后的數(shù)據(jù)取出來。

public VEAVFrame receiveFrame() {
    VEAVFrame frame = new VEAVFrame();
    int outputBufferId = mCodec.dequeueOutputBuffer(mBufferInfo, timeOut);
    if (outputBufferId == MediaCodec.INFO_TRY_AGAIN_LATER) {
        Log.d(TAG, "INFO_TRY_AGAIN_LATER");
        return frame;
    }  else if (outputBufferId < 0) {
        Log.d(TAG, "receiveFrame：" + outputBufferId);
        return frame;
    }
    // outputBuffers[outputBufferId] is ready to be processed or rendered.
    ByteBuffer outputBuffer = mCodec.getOutputBuffer(outputBufferId);
    if (outputBuffer == null) {
        return frame;
    }
    byte[] outData = new byte[mBufferInfo.size];
    outputBuffer.get(outData);
    frame.data = outData;
    mCodec.releaseOutputBuffer(outputBufferId, timeOut);

    return frame;
}

直接渲染到 Surface 上

releaseOutputBuffer 里面的 boolean 變量控制這一幀是否需要渲染僵腺。

public void renderToSurface() {
    int outputBufferId = mCodec.dequeueOutputBuffer(mBufferInfo, timeOut);
    if (outputBufferId < 0) {
        return;
    }
    mCodec.releaseOutputBuffer(outputBufferId, true);
}

結(jié)束

public void stopDecode() {
    mCodec.stop();
    mCodec.release();
}

注意事項

renderToSurface 的頻率需要外部控制鲤孵，不然會一下子全部渲染完了。