Android MediaCodec将原始视频编码为h264

Question

我试图将我的手机相机输出转换为.h264 es格式，但MediaCodec编码器在第一帧后卡在TRY_AGAIN_LATER输出缓冲区状态。相机预览被设置为NV21。

这是相机到编码器：

    mCamera.setPreviewCallback(new Camera.PreviewCallback() {
            private long timestamp=0;
            @Override
            public void onPreviewFrame(byte[] data, Camera camera) {
                byte[] buffer = new byte[data.length];
                encode(data);
            }
        });

编码器初始化：

private void initCodec() {
        try {
            mBufferInfo = new MediaCodec.BufferInfo();
            mMediaCodec = MediaCodec.createEncoderByType("video/avc");
        } catch (IOException e) {
            e.printStackTrace();
        }
        MediaFormat mediaFormat = MediaFormat.createVideoFormat("video/avc",
                1920,
                1080);
        mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, 125000);
        mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, 30);
        mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT,
             MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar);
        mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5);
        mMediaCodec.configure(mediaFormat,
                null,
                null,
                MediaCodec.CONFIGURE_FLAG_ENCODE);
        mMediaCodec.start();
    }

编码器本身：

private synchronized void encode(byte[] data) {
        inputBuffers = mMediaCodec.getInputBuffers();// here changes
        outputBuffers = mMediaCodec.getOutputBuffers();

        int inputBufferIndex = mMediaCodec.dequeueInputBuffer(-1);
        if (inputBufferIndex >= 0) {
            ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
            inputBuffer.clear();
            inputBuffer.put(data);
            mMediaCodec.queueInputBuffer(inputBufferIndex, 0, data.length, 0, 0);
        } else {
            return;
        }

        int outputBufferIndex = mMediaCodec.dequeueOutputBuffer(mBufferInfo, 10000);
        do {
            if (outputBufferIndex >= 0) {
                ByteBuffer outBuffer = outputBuffers[outputBufferIndex];
                System.out.println("buffer info-->" + mBufferInfo.offset + "--"
                        + mBufferInfo.size + "--" + mBufferInfo.flags + "--"
                        + mBufferInfo.presentationTimeUs);
                byte[] outData = new byte[mBufferInfo.size];
                outBuffer.get(outData);
                if (mBufferInfo.offset != 0) {
                    byte[] offsettedData;
                    offsettedData = Arrays.copyOfRange(outData, mBufferInfo.offset, outData.length-1);
                    pushFrame(offsettedData, offsettedData.length);
                } else {
                    pushFrame(outData, outData.length);
                }
                mMediaCodec.releaseOutputBuffer(outputBufferIndex, false);
                outputBufferIndex = mMediaCodec.dequeueOutputBuffer(mBufferInfo,
                        0);

            } else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
                outputBuffers = mMediaCodec.getOutputBuffers();
            } else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
                MediaFormat format = mMediaCodec.getOutputFormat();
            }
        } while (outputBufferIndex >= 0);
    }

为什么输出缓冲区停留在try_again_later（-1）上？所有输入数据似乎都是有效的（来自相机）。