void SetupAssetReaderWriterForAudio(AVAssetTrack audioTrack)
{
if (audioTrack == null)
{
return;
}
// Decompress to Linear PCM with the asset reader
// To read the media data from a specific asset track in the format in which it was stored, pass null to the settings parameter.
AVAssetReaderOutput output = AVAssetReaderTrackOutput.Create(audioTrack, (AudioSettings)null);
if (assetReader.CanAddOutput(output))
{
assetReader.AddOutput(output);
}
AVAssetWriterInput input = AVAssetWriterInput.Create(audioTrack.MediaType, (AudioSettings)null);
if (assetWriter.CanAddInput(input))
{
assetWriter.AddInput(input);
}
// Create and save an instance of ReadWriteSampleBufferChannel,
// which will coordinate the work of reading and writing sample buffers
audioSampleBufferChannel = new AudioChannel(output, input);
}
void ReadSampleBuffers(AVAsset asset)
{
NSError error;
assetReader = AVAssetReader.FromAsset(asset, out error);
if (error != null)
{
Console.WriteLine("Error creating Asset Reader: {0}", error.Description);
}
AVAssetTrack[] videoTracks = asset.TracksWithMediaType(AVMediaType.Video);
AVAssetTrack videoTrack = videoTracks [0];
CreateDecompressionSession(videoTrack);
var videoTrackOutput = AVAssetReaderTrackOutput.Create(videoTrack, (AVVideoSettingsUncompressed)null);
if (assetReader.CanAddOutput(videoTrackOutput))
{
assetReader.AddOutput(videoTrackOutput);
}
if (!assetReader.StartReading())
{
return;
}
while (assetReader.Status == AVAssetReaderStatus.Reading)
{
CMSampleBuffer sampleBuffer = videoTrackOutput.CopyNextSampleBuffer();
if (sampleBuffer != null)
{
VTDecodeFrameFlags flags = VTDecodeFrameFlags.EnableAsynchronousDecompression;
VTDecodeInfoFlags flagOut;
decompressionSession.DecodeFrame(sampleBuffer, flags, IntPtr.Zero, out flagOut);
sampleBuffer.Dispose();
if (presentationTimes.Count >= 5)
{
bufferSemaphore.Wait();
}
}
else if (assetReader.Status == AVAssetReaderStatus.Failed)
{
Console.WriteLine("Asset Reader failed with error: {0}", assetReader.Error.Description);
}
else if (assetReader.Status == AVAssetReaderStatus.Completed)
{
Console.WriteLine("Reached the end of the video.");
ChangeStatus();
ReadSampleBuffers(asset);
}
}
}
void ReadSampleBuffers(AVAsset asset)
{
NSError error;
assetReader = AVAssetReader.FromAsset (asset, out error);
if (error != null)
Console.WriteLine ("Error creating Asset Reader: {0}", error.Description);
AVAssetTrack[] videoTracks = asset.TracksWithMediaType (AVMediaType.Video);
AVAssetTrack videoTrack = videoTracks [0];
CreateDecompressionSession (videoTrack);
var videoTrackOutput = AVAssetReaderTrackOutput.Create (videoTrack, (AVVideoSettingsUncompressed)null);
if (assetReader.CanAddOutput (videoTrackOutput))
assetReader.AddOutput (videoTrackOutput);
if (!assetReader.StartReading ())
return;
while (assetReader.Status == AVAssetReaderStatus.Reading) {
CMSampleBuffer sampleBuffer = videoTrackOutput.CopyNextSampleBuffer ();
if (sampleBuffer != null) {
VTDecodeFrameFlags flags = VTDecodeFrameFlags.EnableAsynchronousDecompression;
VTDecodeInfoFlags flagOut;
decompressionSession.DecodeFrame (sampleBuffer, flags, IntPtr.Zero, out flagOut);
sampleBuffer.Dispose ();
if (presentationTimes.Count >= 5)
bufferSemaphore.Wait ();
} else if (assetReader.Status == AVAssetReaderStatus.Failed) {
Console.WriteLine ("Asset Reader failed with error: {0}", assetReader.Error.Description);
} else if (assetReader.Status == AVAssetReaderStatus.Completed) {
Console.WriteLine("Reached the end of the video.");
ChangeStatus ();
ReadSampleBuffers (asset);
}
}
}
