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

[Steven Liu]

> 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
> 
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> 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