Audio/Video Out of Sync

[RS]

>From: Jim web
>Sent: Wednesday, August 10, 2016 14:33

> Without giving too much away I can tell you that the 'current' HLS is
> served from hosts:

>llnwd.net - Limelight
>edgesuite.net - Akamai

>Manifests served from those hosts will look like:

>#EXTM3U
>#EXT-X-VERSION:2
>## Created with Unified Streaming Platform(version=1.7.18)

># variants
>#EXT-X-STREAM-INF:BANDWIDTH=1013000,CODECS="mp4a.40.2,avc1.4D401E",RESOLUTI
>ON=704x396,FRAME-RATE=25
>vf_b07nsx00_2e5666d8-dfa3-45e9-a812-315abab948f7.ism.hlsv2-audio=128000-vid
>eo=827000.m3u8
>#EXT-X-STREAM-INF:BANDWIDTH=1800000,CODECS="mp4a.40.2,avc1.64001F",RESOLUTI
>ON=704x396,FRAME-RATE=50
>vf_b07nsx00_2e5666d8-dfa3-45e9-a812-315abab948f7.ism.hlsv2-audio=128000-vid
>eo=1570000.m3u8
>#EXT-X-STREAM-INF:BANDWIDTH=3117000,CODECS="mp4a.40.2,avc1.64001F",RESOLUTI
>ON=960x540,FRAME-RATE=50
>vf_b07nsx00_2e5666d8-dfa3-45e9-a812-315abab948f7.ism.hlsv2-audio=128000-vid
>eo=2812000.m3u8
>#EXT-X-STREAM-INF:BANDWIDTH=5510000,CODECS="mp4a.40.2,avc1.640020",RESOLUTI
>ON=1280x720,FRAME-RATE=50
>vf_b07nsx00_2e5666d8-dfa3-45e9-a812-315abab948f7.ism.hlsv2-audio=128000-vid
>eo=5070000.m3u8


>Which gives you 4 bitrate profiles in an ABR (adaptive bitrate) set.
>Note the "Created with Unified Streaming Platform" comment which shows we
>(the BBC) and not Akamai have segmented and packaged the content in-house.

Many thanks for getting this information, and for getting permission to pass 
it on.  Do we know why there is so much emphasis on 50fps?  I can understand 
it is desirable for fast action, but for some content such as chat shows 
5fps would be adequate.  Some content with a lot of fine detail is very slow 
moving.  A bit rate of 5.51Mbit/s for 1280x720 50fps is about 2.5GByte/h, 
which is less than the 3GByte/h of satellite HD .mts streams, but it would 
still be nice to have the option of 1280x720 25fps.

As for HLSHD, we now seem to be getting to the point where every programme 
has missing segments.