Re: [FFmpeg-devel] [PATCH] avformat/demux: in case of no timestamps, calculate dts based on previous dts and duration

From: Anton Khirnov <anton@khirnov.net>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] avformat/demux: in case of no timestamps, calculate dts based on previous dts and duration
Date: Fri, 05 May 2023 13:42:29 +0200
Message-ID: <168328694998.3843.8419543054816695197@lain.khirnov.net> (raw)
In-Reply-To: <20230505113123.28404-1-jeebjp@gmail.com>

Quoting Jan Ekström (2023-05-05 13:31:23)
> From: Martin Machalek <martin.machalek@24i.com>
> 
> Adds DTS to packets which would otherwise break tbr calculation
> within libavformat, as well as packet rate calculation in ffmpeg.
> 
> An example of such input would be an MPEG-TS stream where a whole
> GOP is put into a single PES packet.
> 
> Co-authored-by: Jan Ekström <jan.ekstrom@24i.com>
> 
> Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
> ---
>  libavformat/demux.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/libavformat/demux.c b/libavformat/demux.c
> index 06de71cd6e..9a4ab28679 100644
> --- a/libavformat/demux.c
> +++ b/libavformat/demux.c
> @@ -1098,6 +1098,11 @@ static void compute_pkt_fields(AVFormatContext *s, AVStream *st,
>      if (!onein_oneout)
>          // This should happen on the first packet
>          update_initial_timestamps(s, pkt->stream_index, pkt->dts, pkt->pts, pkt);
> +
> +    if (pkt->dts == AV_NOPTS_VALUE && !is_relative(sti->cur_dts) &&
> +        sti->cur_dts != AV_NOPTS_VALUE && pkt->duration > 0)
> +        pkt->dts = sti->cur_dts + pkt->duration;

This function really does not need more arbitrary guesses.

-- 
Anton Khirnov
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