[FFmpeg-devel] [PATCH] Fix first_pcr initial update

[lance.lmwang at gmail.com]

On Tue, Nov 02, 2021 at 12:47:57PM +0200, Maksym Veremeyenko wrote:
> One of latest commit https://source.ffmpeg.org/?p=ffmpeg.git;a=commitdiff;h=6f36eb0da71d22aadf8f056f0966bd86656ea57e
> claim it fixes endless loop on package generation if muxrate specified and
> copyts used. But actually it does not work properly if *-mpegts_copyts 1*
> specified:
> 
> ffmpeg -y -copyts -i loewe.ts -c:v libx264 -x264opts nal-hrd=cbr:force-cfr=1
> -b:v 3500k -minrate 3500k -maxrate 3500k -bufsize 1000k  -c:a mp2 -f mpegts
> -mpegts_copyts 1 -muxrate 4500k -vframes 1000 test.ts
> 

> ffmpeg generate huge file until it reach zero-based pcr value equal to first
> dts.
> 
> attached patch fix it.
> 
> 
> -- 
> Maksym Veremeyenko

> From fff0339c6d764e18fc4ecf111d035095309dc4d4 Mon Sep 17 00:00:00 2001
> From: Maksym Veremeyenko <verem at m1.tv>
> Date: Tue, 2 Nov 2021 12:33:54 +0200
> Subject: [PATCH] Fix first_pcr initial update
> 
> ---
>  libavformat/mpegtsenc.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index 35c835c..32786be 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -1693,17 +1693,17 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
>          stream_id = side_data[0];
>  
>      if (ts->copyts < 1) {
> -        if (!ts->first_dts_checked && dts != AV_NOPTS_VALUE) {
> -            ts->first_pcr += dts * 300;
> -            ts->first_dts_checked = 1;
> -        }
> -
>          if (pts != AV_NOPTS_VALUE)
>              pts += delay;
>          if (dts != AV_NOPTS_VALUE)
>              dts += delay;
>      }
>  
> +    if (!ts->first_dts_checked && dts != AV_NOPTS_VALUE) {
> +        ts->first_pcr += dts * 300;
> +        ts->first_dts_checked = 1;
> +    }
> +

I think it's not same as the old code, the first_pcr will add extra delay if copyts is
0.

>      if (!ts_st->first_timestamp_checked && (pts == AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE)) {
>          av_log(s, AV_LOG_ERROR, "first pts and dts value must be set\n");
>          return AVERROR_INVALIDDATA;
> -- 
> 1.8.3.1
> 

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-- 
Thanks,
Limin Wang