[FFmpeg-devel] [PATCH] avformat/hls: Set AVFMT_TS_DISCONT flag on HLS input format

[Dennis Mungai]

On Tue, 29 Oct 2019 at 06:07, Steven Liu <lq at chinaffmpeg.org> wrote:
>
>
>
> > 在 2019年10月29日，01:09，Dennis Mungai <dmngaie at gmail.com> 写道：
> >
> > On Mon, 28 Oct 2019 at 05:45, Steven Liu <lq at chinaffmpeg.org> wrote:
> >>
> >>
> >>
> >>> 在 2019年10月28日，02:39，Philip Langdale <philipl at overt.org> 写道：
> >>>
> >>> There have been many reports over the years about problems when
> >>> taking an HLS stream as input to `ffmpeg` where there are timestamp
> >>> discontinuities present. This is explicitly supported in the
> >>> HLS spec (EXT-X-DISCONTINUITY) and often used for ad injection.
> >>>
> >>> Various fixes and work-arounds have been proposed over the years,
> >>> but one step that seems obvious, even if it's not a complete fix,
> >>> is to mark the HLS input format as supporting discontinuities. This
> >>> will prevent timestamp fixup logic in ffmpeg.c kicking in that ends
> >>> up mangling the timestamps unnecessarily.
> >>>
> >>> I've tested this out with an example provided by Joe Koberg early
> >>> last year, and it is sufficient to allow `ffmpeg` to download and
> >>> mux the stream correctly. Joe had briefly suggested that other
> >>> situations can still be handled incorrectly, but this seems like
> >>> a strict improvement.
> >>>
> >>> Joe's example:
> >>>
> >>> https://s3.amazonaws.com/playon-test-videos/discont_test_new/discont_test.m3u8
> >>> ---
> >>> libavformat/hls.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/libavformat/hls.c b/libavformat/hls.c
> >>> index d7f4d5b442..ac151d5ca4 100644
> >>> --- a/libavformat/hls.c
> >>> +++ b/libavformat/hls.c
> >>> @@ -2326,7 +2326,7 @@ AVInputFormat ff_hls_demuxer = {
> >>>    .long_name      = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming"),
> >>>    .priv_class     = &hls_class,
> >>>    .priv_data_size = sizeof(HLSContext),
> >>> -    .flags          = AVFMT_NOGENSEARCH,
> >>> +    .flags          = AVFMT_NOGENSEARCH | AVFMT_TS_DISCONT,
> >>>    .read_probe     = hls_probe,
> >>>    .read_header    = hls_read_header,
> >>>    .read_packet    = hls_read_packet,
> >>> --
> >>> 2.20.1
> >>>
> >>> _______________________________________________
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> >>>
> >>> To unsubscribe, visit link above, or email
> >>> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe”.
> >>
> >> LGTM, whatever other more reasons, this can fix one of those problems.
> >>
> >> Thanks
> >> Steven
> >
> > This patch actually fixes the occurence of DTS and PTS discontinuities
> > I've been seeing with (some) HLS inputs that have discontinuities due
> > to ad insertion(s). 10+ hours later without a single discontinuity.
>
> Thanks Dennis, Will push this patch after 24hours if there have no objections.
> > _______________________________________________
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> > ffmpeg-devel at ffmpeg.org
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> >
> > To unsubscribe, visit link above, or email
> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>
> Thanks
> Steven


Looking forward