Is there any way to re-encode a PCM wav file to another encoding using standard Android SDK?
I can see that is is possible to directly record from the mic into these formats but the app I'm writing has to record in PCM first. Due to licensing restraints, ffmpeg is not an available option.
I now have the following code for Jelly bean but the output is not readable by any media players.
The stage fright code from aosp seems to suggest an mpeg4 container
profile.nSampleRate = sampleRate;
profile.nBitRate = bitRate;
profile.nAudioBandWidth = 0;
profile.nFrameLength = 0;
profile.nAACtools = OMX_AUDIO_AACToolAll;
profile.nAACERtools = OMX_AUDIO_AACERNone;
profile.eAACProfile = (OMX_AUDIO_AACPROFILETYPE) aacProfile;
profile.eAACStreamFormat = OMX_AUDIO_AACStreamFormatMP4FF;
But the output from the android code is not readable.
The input wav file is 32khz, 16bit signed mono as required.
public void doConvert( View v)
{
new AsyncTask<Void, Void, Void>()
{
@Override
protected Void doInBackground(Void... params)
{
try
{
int codecCount = MediaCodecList.getCodecCount();
for ( int i=0; i < codecCount; i++)
{
MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, info.getName());
for ( String type : info.getSupportedTypes() )
{
Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, type);
}
}
File inputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Media/Report-test5.wav");
FileInputStream fis = new FileInputStream(inputFile);
fis.skip(44);//remove wav header
File outputFile = new File( Environment.getExternalStorageDirectory().getAbsolutePath()+"/Media/out.mp4");
if ( outputFile.exists()) outputFile.delete();
FileOutputStream fos = new FileOutputStream(outputFile);
MediaCodec codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
MediaFormat outputFormat = MediaFormat.createAudioFormat("audio/mp4a-latm", 32000, 1);
outputFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
//outputFormat.setInteger(MediaFormat.KEY_CHANNEL_MASK, AudioFormat.CHANNEL_OUT_MONO);
outputFormat.setInteger(MediaFormat.KEY_BIT_RATE, 48000 );
//outputFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 64000);
double durationInMs = (inputFile.length()/64.0)*1000.0;
outputFormat.setLong(MediaFormat.KEY_DURATION, (long)durationInMs );
//Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, codec.getOutputFormat().toString());
codec.configure(outputFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE );
codec.start();
ByteBuffer[] inputBuffers = codec.getInputBuffers();
ByteBuffer[] outputBuffer = codec.getOutputBuffers();
boolean hasMoreData = true;
MediaCodec.BufferInfo outBuffInfo = new BufferInfo();
byte readBuffer[] = new byte[64000];
byte writeBuffer[] = new byte[64000];
do
{
int nextBuffer = codec.dequeueInputBuffer(1000);
logger.log(Level.INFO,"nextInputBuffer = "+nextBuffer);
if ( nextBuffer >= 0 )
{
ByteBuffer inBuf = inputBuffers[nextBuffer];
inBuf.clear();
int bytesRead = fis.read( readBuffer,0, inBuf.capacity() );
logger.log(Level.INFO,"Read = "+bytesRead);
if ( bytesRead < inBuf.capacity() )
{
hasMoreData = false;
}
inBuf.put(readBuffer, 0, bytesRead );
codec.queueInputBuffer(nextBuffer, 0, bytesRead, 0, hasMoreData?0:MediaCodec.BUFFER_FLAG_END_OF_STREAM);
}
int outputBufferIndex = codec.dequeueOutputBuffer( outBuffInfo, 1000 );
logger.log(Level.INFO,"nextOutputBuffer = "+outputBufferIndex);
logger.log(Level.INFO,"outBuffInfo offset = "+outBuffInfo.offset);
logger.log(Level.INFO,"outBuffInfo size = "+outBuffInfo.size);
logger.log(Level.INFO,"outBuffInfo flags = "+outBuffInfo.flags);
//while ( outputBufferIndex > -1 )
//{
outputBuffer[outputBufferIndex].position(outBuffInfo.offset);
outputBuffer[outputBufferIndex].get(writeBuffer,0,outBuffInfo.size);
fos.write(writeBuffer,0, outBuffInfo.size);
logger.log(Level.INFO,"Writing = "+outBuffInfo.size+" bytes");
outputBuffer[outputBufferIndex].clear();
codec.releaseOutputBuffer(outputBufferIndex, false);
if ( outBuffInfo.flags == MediaCodec.BUFFER_FLAG_END_OF_STREAM )
{
codec.flush();
codec.stop();
codec.release();
break;
}
//outputBufferIndex = codec.dequeueOutputBuffer( outBuffInfo, 1000 );
//logger.log(Level.INFO,"nextOutputBuffer = "+outputBufferIndex);
//}
} while ( outBuffInfo.flags != MediaCodec.BUFFER_FLAG_END_OF_STREAM);
fis.close();
fos.flush();
fos.close();
}
catch ( Exception e)
{
Logger.getLogger(MainActivity.class.getSimpleName()).log(Level.INFO, "Codec Error",e);
}
logger.log(Level.INFO,"Done");
return null;
}
}.execute();
}
Basically, you are writing all the generated encoded buffers into a file, but that is missing all sorts of MetaData related to the tracks/samples/file etc.
I guess the solutions I can think of is : either you can find a good muxer library to write the buffers into the right file format, or you have to wait and see whether the future Android will provide such APIs for you.