Android MediaCodec和MediaMuxer中的getInpuBuffer

Question

Below is a fragment of Android MediaMuxer API sample code: https://developer.android.com/reference/android/media/MediaMuxer.html

MediaMuxer muxer = new MediaMuxer("temp.mp4", OutputFormat.MUXER_OUTPUT_MPEG_4);
 // More often, the MediaFormat will be retrieved from MediaCodec.getOutputFormat()
 // or MediaExtractor.getTrackFormat().
 MediaFormat audioFormat = new MediaFormat(...);
 MediaFormat videoFormat = new MediaFormat(...);
 int audioTrackIndex = muxer.addTrack(audioFormat);
 int videoTrackIndex = muxer.addTrack(videoFormat);
 ByteBuffer inputBuffer = ByteBuffer.allocate(bufferSize);
 boolean finished = false;
 BufferInfo bufferInfo = new BufferInfo();

 muxer.start();
 while(!finished) {
   // getInputBuffer() will fill the inputBuffer with one frame of encoded
   // sample from either MediaCodec or MediaExtractor, set isAudioSample to
   // true when the sample is audio data, set up all the fields of bufferInfo,
   // and return true if there are no more samples.
   finished = getInputBuffer(inputBuffer, isAudioSample, bufferInfo);
   if (!finished) {
     int currentTrackIndex = isAudioSample ? audioTrackIndex : videoTrackIndex;
     muxer.writeSampleData(currentTrackIndex, inputBuffer, bufferInfo);
   }
 };
 muxer.stop();
 muxer.release();

For this line: finished = getInputBuffer(inputBuffer, isAudioSample, bufferInfo); I didn't find this function getInputBuffer in both MediaCodec.java and MediaMuxer.java, is that a user defined function or API function?

Answer 1

In this case, getInputBuffer is a hypothetical user defined function. It is not an API function. The comment above it explains what it is supposed to do. (Note how it wouldn't actually work in the way it is written, since the isAudioSample variable can't be updated by the function in the way it is exactly written either.)