On Fri, Apr 19, 2019 at 08:47:34AM +0000, Andreas Håkon via ffmpeg-devel wrote: > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > On Thursday, 18 de April de 2019 11:01, Andreas Håkon via ffmpeg-devel > <ffmpeg-devel@ffmpeg.org> wrote: > > > Hi, > > > > This patch resolves one very specific use case: > > > > - When you use the mpegts muxer; > > - And use the global parameter “-copyts”; > > - And use the parameter “-muxrate” for the mpegts muxer; > > - And use too the parameter “-mpegts_copyts”. > > > > The problem is created because the member “first_pcr” of the > > MpegTSWrite struct isn’t initialized with a correct timestamp (so when > > copying the timestamps the initial value is 0). And in this case an > > infinite loop is created because the code never writes PES packets when the > > “mux_rate” isn’t VBR (equals to 1). See the block that creates the loop > > here (note the "continue" command at end): > > > > https://github.com/FFmpeg/FFmpeg/blob/a0559fcd81f42f446c93357a943699f9d44eeb79/libavformat/mpegtsenc.c#L1211 > > > > So, this patch fixes the problem initializing the “first_pcr” with the > > first DTS value that comes when using the incoming timestamps. > > > > Regards. > > A.H. > > > > Hi, > > Here a new version of the patch. > > The "fist_pcr" value is now derived from DTS in a more consistent way. > > Regards, > A.H. > > > --- >
> From c59569ca9426fef455edabfa648cb2ff678c1640 Mon Sep 17 00:00:00 2001
> From: Andreas Hakon <andreas.ha...@protonmail.com>
> Date: Fri, 19 Apr 2019 09:32:33 +0100
> Subject: [PATCH] libavformat: fix copyts and muxrate in mpegts muxer v2
>
> When using "-copyts" and "-muxrate" with the mpegts muxer the muxing fails
> because the member "first_pcr" of the MpegTSWrite struct isn't initialized
> with a correct timestamp.
>
> The behaviour of the error is an infinite loop created in the function
> mpegts_write_pes() because the code never writes PES packets.
>
> This patch resolves the problem initializing the "first_pcr" with a value
> derived from the first DTS value seen.
>
> Signed-off-by: Andreas Hakon <andreas.ha...@protonmail.com>
> ---
> libavformat/mpegtsenc.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index fc0ea22..858b0d7 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -971,6 +971,9 @@ static int mpegts_init(AVFormatContext *s)
>
> if (ts->copyts < 1)
> ts->first_pcr = av_rescale(s->max_delay, PCR_TIME_BASE,
> AV_TIME_BASE);
> + else
> + ts->first_pcr = AV_NOPTS_VALUE;
> +
> } else {
> /* Arbitrary values, PAT/PMT will also be written on video key
> frames */
> ts->sdt_packet_period = 200;
> @@ -1186,12 +1189,16 @@ static void mpegts_write_pes(AVFormatContext *s,
> AVStream *st,
> int64_t pcr = -1; /* avoid warning */
> int64_t delay = av_rescale(s->max_delay, 90000, AV_TIME_BASE);
> int force_pat = st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && key &&
> !ts_st->prev_payload_key;
> + int last_payload_size = 0;
>
> av_assert0(ts_st->payload != buf || st->codecpar->codec_type !=
> AVMEDIA_TYPE_VIDEO);
> if (ts->flags & MPEGTS_FLAG_PAT_PMT_AT_FRAMES &&
> st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
> force_pat = 1;
> }
>
> + if (ts->mux_rate > 1 && dts != AV_NOPTS_VALUE && ts->first_pcr ==
> AV_NOPTS_VALUE)
> + ts->first_pcr = (dts * 300) - av_rescale(s->max_delay,
> PCR_TIME_BASE, AV_TIME_BASE);
> +
if this doesnt execute first_pcr could remain AV_NOPTS_VALUE, this looks
a bit fragile to me as there is code using first_pcr with implicit assumtation
that it is not AV_NOPTS_VALUE in get_pcr().
is something preventing this combination ?
> is_start = 1;
> while (payload_size > 0) {
> retransmit_si_info(s, force_pat, dts);
> @@ -1209,12 +1216,13 @@ static void mpegts_write_pes(AVFormatContext *s,
> AVStream *st,
> }
>
> if (ts->mux_rate > 1 && dts != AV_NOPTS_VALUE &&
> - (dts - get_pcr(ts, s->pb) / 300) > delay) {
> + last_payload_size != payload_size && (dts - get_pcr(ts, s->pb) /
> 300) > delay) {
> /* pcr insert gets priority over null packet insert */
> if (write_pcr)
> mpegts_insert_pcr_only(s, st);
> else
> mpegts_insert_null_packet(s);
> + last_payload_size = payload_size;
why is the check on payload_size needed ? (it is not for the testcase)
the commit message also seems not to explain this part
thanks
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
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