Getting PCM data of HLS from AVPlayer - ios

Question

This question seems to be asked few times over last few years but none has answer for that. I am trying to process PCM data from HLS and I have to use AVPlayer.
this post taps the local files
https://chritto.wordpress.com/2013/01/07/processing-avplayers-audio-with-mtaudioprocessingtap/
and this tap work with remote files but not with .m3u8 hls files.
http://venodesigns.net/2014/01/08/recording-live-audio-streams-on-ios/
I can play first two tracks in the playlist but it doesn't start the needed callbacks to get the pcm, when the file is local or remote(not stream) I can still get the pcm but it is the hls is not working and I need HLS working
here is my code
//avplayer tap try
- (void)viewDidLoad {
[super viewDidLoad];
NSURL*testUrl= [NSURL URLWithString:#"http://playlists.ihrhls.com/c5/1469/playlist.m3u8"];
AVPlayerItem *item = [AVPlayerItem playerItemWithURL:testUrl];
self.player = [AVPlayer playerWithPlayerItem:item];
// Watch the status property - when this is good to go, we can access the
// underlying AVAssetTrack we need.
[item addObserver:self forKeyPath:#"status" options:0 context:nil];
}
-(void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context
{
if(![keyPath isEqualToString:#"status"])
return;
AVPlayerItem *item = (AVPlayerItem *)object;
if(item.status != AVPlayerItemStatusReadyToPlay)
return;
NSArray *tracks = [self.player.currentItem tracks];
for(AVPlayerItemTrack *track in tracks) {
if([track.assetTrack.mediaType isEqualToString:AVMediaTypeAudio]) {
NSLog(#"GOT DAT FUCKER");
[self beginRecordingAudioFromTrack:track.assetTrack];
[self.player play];
}
}
}
- (void)beginRecordingAudioFromTrack:(AVAssetTrack *)audioTrack
{
// Configure an MTAudioProcessingTap to handle things.
MTAudioProcessingTapRef tap;
MTAudioProcessingTapCallbacks callbacks;
callbacks.version = kMTAudioProcessingTapCallbacksVersion_0;
callbacks.clientInfo = (__bridge void *)(self);
callbacks.init = init;
callbacks.prepare = prepare;
callbacks.process = process;
callbacks.unprepare = unprepare;
callbacks.finalize = finalize;
OSStatus err = MTAudioProcessingTapCreate(
kCFAllocatorDefault,
&callbacks,
kMTAudioProcessingTapCreationFlag_PostEffects,
&tap
);
if(err) {
NSLog(#"Unable to create the Audio Processing Tap %d", (int)err);
return;
}
// Create an AudioMix and assign it to our currently playing "item", which
// is just the stream itself.
AVMutableAudioMix *audioMix = [AVMutableAudioMix audioMix];
AVMutableAudioMixInputParameters *inputParams = [AVMutableAudioMixInputParameters
audioMixInputParametersWithTrack:audioTrack];
inputParams.audioTapProcessor = tap;
audioMix.inputParameters = #[inputParams];
self.player.currentItem.audioMix = audioMix;
}
void process(MTAudioProcessingTapRef tap, CMItemCount numberFrames,
MTAudioProcessingTapFlags flags, AudioBufferList *bufferListInOut,
CMItemCount *numberFramesOut, MTAudioProcessingTapFlags *flagsOut)
{
OSStatus err = MTAudioProcessingTapGetSourceAudio(tap, numberFrames, bufferListInOut,
flagsOut, NULL, numberFramesOut);
if (err) NSLog(#"Error from GetSourceAudio: %d", (int)err);
NSLog(#"Process");
}
void init(MTAudioProcessingTapRef tap, void *clientInfo, void **tapStorageOut)
{
NSLog(#"Initialising the Audio Tap Processor");
*tapStorageOut = clientInfo;
}
void finalize(MTAudioProcessingTapRef tap)
{
NSLog(#"Finalizing the Audio Tap Processor");
}
void prepare(MTAudioProcessingTapRef tap, CMItemCount maxFrames, const AudioStreamBasicDescription *processingFormat)
{
NSLog(#"Preparing the Audio Tap Processor");
}
void unprepare(MTAudioProcessingTapRef tap)
{
NSLog(#"Unpreparing the Audio Tap Processor");
}
void init is called void prepare and process has to be called as well.
how can I do this?

Answer 1

I would suggest you use FFMPEG library to process HLS streams. This is a little harder but gives more flexibility. I did HLS Player for Android a few years ago (used this project) I believe same applies to iOS.

Answer 2

I recommended to use Novocaine
Really fast audio in iOS and Mac OS X using Audio Units is hard, and will leave you scarred and bloody. What used to take days can now be done with just a few lines of code.