[FFmpeg-user] problems consuming live single file hls

Daniel Oberhoff danieloberhoff at googlemail.com
Mon Jan 14 10:48:44 EET 2019

>>>> Since hls is a streaming format i would actually expect this to work.
>>> It does work for "multi file" which is what hls is meant to be.
>> Byte-range is part of the standard (see
>> https://tools.ietf.org/html/draft-pantos-http-live-streaming-08#section-3.4.1),
>> so single file is as much "meant to be" as multi-file afaict.
> But the playlist does not change or does it?

Ah, I think now I understand where we missed each other: Yes it does!
That is one of the central points in HLS: Video is produced in segments
(either in separate files or by appending to one file, but in either
case playable individually). After a segment is produced it is
"published" via the playlist by appending some lines to it. To do this
atomic the file is usually copied, appended to, and then "swapped" back
in via rename.

The single file hls implementation in ffmpeg somehow fails to properly
order these things, i.e. segments become visible in the playlist before
they are fully written, breaking the standard hls consumer pattern.

>>> If you use single file, I don't see how the behaviour can be
>>> different, you can reproduce it using mpegts on your local
>>> file system.
>> What do you mean? The desire is for new entries in the playlist to
>> become visible only after the data is visible to open/read. You are
>> saying this is impossible? I cant imagine that to be honest. Would you
>> accept a patch if i can get this to work?
> Patches are always preferred over bug reports (but bug reports
> are very welcome), and there is no doubt that I may completely
> misunderstand the issue.

I think to some extent that happened (see above where i try to
reconcile), but that my be entirely my fault. I will see what I can do.


Daniel Oberhoff

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