iOS online radio streaming questions

问题:

I have to create app that provides online radio streaming (icecast), preferably .ogg format. So I have next questions:

1. How can I play .ogg format audio stream? Are there any supported classes? Because I can't find any, so I think that it is impossible without many bitwise operations using CFNetwork, CoreAudio, AudioToolbox etc. (I don't look at cocos2d, because it's ridiculous) Am i wrong?
2. I'm playing mp3 stream for now (no possibility for .ogg for me). I tried to use AVPlayer, MPMovieMediaController, AudioSreaming lib by MattGallagher and by DigitalDJ, and none of these solutions can't provides me metadata access.

For AVPlayer:

   -(void)playButtonPressed:(id)sender
    {
        NSURL *grindURL = [NSURL URLWithString:@"http://radio.goha.ru:8000/grind.fm"];
                    grindFMPlayer = [[AVPlayer alloc] initWithURL:grindURL];
                    [grindFMPlayer.currentItem addObserver:self forKeyPath:@"status" options:0 context:nil]; 
                    AVPlayerItem *item = grindFMPlayer.currentItem;
                    [grindFMPlayer play];
    }

-(void)stopButtonPressed:(id)sender
{
            AVURLAsset *ass = grindFMPlayer.currentItem.asset;
            NSArray *arr = [ass commonMetadata];
            NSArray *it_meta = [grindFMPlayer.currentItem timedMetadata];
            [grindFMPlayer pause];
}

arr and it_meta count always 0, no song\artist\any metadata.
The same for the MPMovieMediaController, metadataUpdate never called

streamAudioPlayer = [[MPMoviePlayerController alloc] 
                                                   initWithContentURL:[NSURL URLWithString:@"http://radio.goha.ru:8000/grind.fm"];
                streamAudioPlayer.movieSourceType = MPMovieSourceTypeStreaming;
                [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(MetadataUpdate:) name:MPMoviePlayerTimedMetadataUpdatedNotification object:nil];
[streamAudioPlayer play];

and in stop button method:

timedMeta = [streamAudioPlayer timedMetadata];
            if ([streamAudioPlayer timedMetadata]!=nil && [[streamAudioPlayer timedMetadata] count] > 0) 
            {
                NSLog(@"metadata count = %d", [[streamAudioPlayer timedMetadata] count]);
                for (MPTimedMetadata *metadata in [streamAudioPlayer timedMetadata]) 
                {
                    NSLog(@"description %@", metadata.allMetadata);
                    if ([[metadata.allMetadata valueForKey:@"key"] isEqualToString:@"title"]) 
                    {
                        NSString *text = [metadata.allMetadata valueForKey:@"value"];
                        NSString* filename = text;
                    }
                }
            }

[streamAudioPlayer timedMetadata] always nil.

I've tried

• https://github.com/mattgallagher/AudioStreamer
• https://github.com/DigitalDJ/AudioStreamer

These 2 projects for shoutcast and icecast - http://www.mikejablonski.org/2009/04/17/reading-shoutcast-metadata-from-a-stream/

But still have no luck to get current playing track info, which only obtains in SHOUTcast app as

1st Metadata = 'StreamTitle=',

2nd metadata = '' and bitrate = '128000'
(So I think I have to have deal with bytes from http headers response or something like this? but wtf, it's shoutcast metadata, but my radiostream is icecast. Have no idea)
I would be grateful for any help!

回答1:

Icecast and Shoutcast are compatible with each other. The difference lies in the way they respond to a HTTP GET request. When you send a HTTP GET request to an Icecast server it will reply with a HTTP 200 OK response. The response headers will contain values for the icy-br, icy-metaint, icy-name, icy-genre and icy-url keys.

When you send a HTTP GET request to a Shoutcast server it will respond with a ICY 200 OK response. In this case you'll have to parse the response data because the metadata will not be available in the response headers.

The most important metadata key is the icy-metaint key. This value will tell you how often the metadata is sent in the stream. For more information about parsing this metadata have a look at this website: Shoutcast Metadata Protocol

To play ogg streams you'll need to use the open source FFmpeg library. This library can be compiled for the iOS platform and used to connect and decode ogg streams.

回答2:

To play an ogg formatted audio stream, you would need to supply a codec. iOS does not have native support for the ogg format

回答3:

I think the first thing to do is to "order" the meta data by setting the request header:

CFHTTPMessageSetHeaderFieldValue(message, CFSTR("Icy-MetaData"), CFSTR("1"));

In my case I added this line to Matt Galaghers's Audio Streamer. The result was that I could actually hear the metadata when the stream was playing because it was contained in the stream data. The next step was to filter the meta data out and interpret it. To achieve this all the necessary information are already mentioned here.

Good luck!