[FFmpeg-trac] #1842(undetermined:open): Incorrect segmented HTTP Live Streaming playlists

[FFmpeg]

#1842: Incorrect segmented HTTP Live Streaming playlists
-------------------------------------+-------------------------------------
             Reporter:  teric        |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:
              Version:  1.0          |  undetermined
             Keywords:               |               Resolution:
  segment,hls,m3u8                   |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by teric):

 @upeters, @brownard

 #EXT-X-MEDIA-SEQUENCE should EQUAL or LESS THAN the first item index in
 current list.
 my original patch can create a sliding window.

 Replying to [comment:4 brownard]:
 > The problem is that the segmenter doesn't correctly increment the #EXT-X
 -MEDIA-SEQUENCE tag as per the spec and I don't think the -segment-list-
 size works as the spec envisages.
 > The current behaviour is to completely empty the playlist when it
 reaches the specified size and increment the #EXT-X-MEDIA-SEQUENCE tag by
 1
 > e.g
 >
 > {{{
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:0
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 000.ts
 > #EXTINF:10,
 > 001.ts
 > #EXTINF:10,
 > 002.ts
 >
 > .....
 >
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:1
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 003.ts
 >
 > .....
 >
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:1
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 003.ts
 > #EXTINF:10,
 > 004.ts
 > }}}
 >
 > but the #EXT-X-MEDIA-SEQUENCE tag should be equal to the index of the
 first segment in the list, so in the example above the value in the second
 and third playlist should be 3 not 1 because the first segment in the list
 is the fourth overall.
 >
 > What should happen is rather than emptying the playlist, the first item
 in the list should be removed and the new item appended so you have a
 "sliding window" with the #EXT-X-MEDIA-SEQUENCE increasing by 1 each time
 > e.g
 >
 > {{{
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:0
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 000.ts
 > #EXTINF:10,
 > 001.ts
 > #EXTINF:10,
 > 002.ts
 >
 > .....
 >
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:1
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 001.ts
 > #EXTINF:10,
 > 002.ts
 > #EXTINF:10,
 > 003.ts
 >
 > .....
 >
 > #EXTM3U
 > #EXT-X-MEDIA-SEQUENCE:2
 > #EXT-X-TARGETDURATION:10
 > #EXTINF:10,
 > 002.ts
 > #EXTINF:10,
 > 003.ts
 > #EXTINF:10,
 > 004.ts
 > }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1842#comment:7>
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