Alternate audio tracks with HTTP Live Streaming

问题:

I'm generating a list of available audio tracks when an HLS stream is ready to play. I can access the available audio tracks just fine, but I'm having difficulty extracting the correct 'Title' for each track.

I'm using Apple's test stream which has two audio tracks. I extract the tracks with this...

availableAudioTrackList = [[NSMutableArray alloc] init]; AVMediaSelectionGroup *audioTracks = [player.currentItem.asset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicAudible]; for (int i = 0; i < [audioTracks.options count]; i++) {     AVMediaSelectionOption *opt = audioTracks.options[i];     NSLog(@"Opt: %@", opt);     [availableAudioTrackList insertObject:opt.displayName atIndex:i]; } NSLog(@"Audio Track Array: %@", availableAudioTrackList); 

My output shows that 'opt.displayName' does not give the title of BipBop Audio 1 and BipBop Audio 2 (these are the distinguishing names I want to be able to use).

... Opt: <AVMediaSelectionKeyValueOption: 0x15dad0d0, locale = en, mediaType = 'soun', title = BipBop Audio 1, default = YES>  ... Opt: <AVMediaSelectionKeyValueOption: 0x15dad100, locale = en, mediaType = 'soun', title = BipBop Audio 2>  ...Audio Track Array: ( English, English ) 

Any idea how/if I can extract the title from the AVMediaSelectionOption object?

Thanks!

回答1:

You have to fetch it from metadata as follows

    NSArray *metaDatas = [AVMetadataItem metadataItemsFromArray:opt.commonMetadata withKey:@"title" keySpace:@"comn"];     if (metaDatas.count > 0) {       NSString *title = ((AVMetadataItem*)[metaDatas objectAtIndex:0]).stringValue;       NSLog(@"title: %@", title);     } 

文章来源: Alternate audio tracks with HTTP Live Streaming