Editing audio track names in the OTT playlist/manifest¶

Editing audio track names¶

When transcoding a stream that contains multiple audio tracks with the split_channels=true parameter enabled, Flussonic Media Server splits each stereo pair into separate mono tracks. By default, these tracks receive generic names such as undefined a1, undefined a2, etc. in the OTT master playlist/manifest.

For example to set meaningful values for the NAME and LANGUAGE parameters in the #EXT-X-MEDIA tags of the HLS master playlist, use the input_media_info block in the stream configuration. This block lets you override metadata (in particular language and title) for each input audio track before channel splitting.

The language parameter is applied to the entire audio track (stereo pair). After split_channels=true the mono tracks inherit this value, and Flussonic automatically appends the suffix aX (where X is the channel number).

Example configuration for a source with two stereo pairs (after splitting — 4 mono tracks):

stream fake_ts {
    input tshttp://es1.e/fake/mpegts;
    input_media_info {
        track {
            content video;
        }
        track {
            content audio;
            match index=1;
            language eng;
        }
        track {
            content audio;
            match index=2;
            language rus;
        }
    }
    transcoder vb=1000k vb=700k vcodec=h264 size=1280x720:fit:#000000 ab=64k split_channels=true;
}

As a result, the HLS master playlist will contain approximately the following (This also applies to DASH):

#EXTM3U
#EXT-X-MEDIA:URI="tracks-a1/mono.ts.m3u8?hls_proxy_host=...",TYPE=AUDIO,GROUP-ID="aac",NAME="eng a1",LANGUAGE="eng",DEFAULT=YES
#EXT-X-MEDIA:URI="tracks-a2/mono.ts.m3u8?hls_proxy_host=...",TYPE=AUDIO,GROUP-ID="aac",NAME="eng a2",LANGUAGE="eng",DEFAULT=NO
#EXT-X-MEDIA:URI="tracks-a3/mono.ts.m3u8?hls_proxy_host=...",TYPE=AUDIO,GROUP-ID="aac",NAME="rus a3",LANGUAGE="rus",DEFAULT=NO
#EXT-X-MEDIA:URI="tracks-a4/mono.ts.m3u8?hls_proxy_host=...",TYPE=AUDIO,GROUP-ID="aac",NAME="rus a4",LANGUAGE="rus",DEFAULT=NO
#EXT-X-STREAM-INF:...

Important
The language parameter is applied before channel splitting. If the source has only two audio tracks, you cannot specify match index=3 or match index=4 — these indices appear only after split_channels=true.

For finer control over metadata (see the API reference for details).