Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add -reprobe_stream_if_pmt_es_stream_type_changes option

[Marton Balint <cus@passwd.hu>]

On Sat, 14 Jun 2025, Pavel Koshevoy wrote:

> Make runtime AVStream.codecpar codec_id updates optional and disabled
> by default, so that avformat API clients can enable this feature explicitly
> when they add support for runtime codec changes.
> ---
> libavformat/mpegts.c | 8 +++++++-
> tests/fate/demux.mak | 2 +-

Documentation is missing.

> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> index deb69a0548..88b1754307 100644
> --- a/libavformat/mpegts.c
> +++ b/libavformat/mpegts.c
> @@ -156,6 +156,8 @@ struct MpegTSContext {
>     /** to detect seek */
>     int64_t last_pos;
>
> +    int reprobe_stream_if_pmt_es_stream_type_changes;
> +
>     int skip_changes;
>     int skip_clear;
>     int skip_unknown_pmt;
> @@ -199,6 +201,8 @@ static const AVOption options[] = {
>     MPEGTS_OPTIONS,
>     {"fix_teletext_pts", "try to fix pts values of dvb teletext streams", offsetof(MpegTSContext, fix_teletext_pts), AV_OPT_TYPE_BOOL,
>      {.i64 = 1}, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
> +    {"reprobe_stream_if_pmt_es_stream_type_changes", "allow PMT updates to change codec_type and codec_id at runtime",
> +     offsetof(MpegTSContext, reprobe_stream_if_pmt_es_stream_type_changes), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM },

The option name is a very long and way too specific. Maybe 
-allow_codec_changes is shorter and more understandable?

Thanks,
Marton


>     {"scan_all_pmts", "scan and combine all PMTs", offsetof(MpegTSContext, scan_all_pmts), AV_OPT_TYPE_BOOL,
>      {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM },
>     {"skip_unknown_pmt", "skip PMTs for programs not advertised in the PAT", offsetof(MpegTSContext, skip_unknown_pmt), AV_OPT_TYPE_BOOL,
> @@ -2510,7 +2514,9 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
>         if (!st)
>             goto out;
>
> -        if (pes && pes->stream_type != stream_type)
> +        if (pes && (!pes->stream_type ||
> +                    (pes->stream_type != stream_type &&
> +                     ts->reprobe_stream_if_pmt_es_stream_type_changes)))
>             mpegts_set_stream_info(st, pes, stream_type, prog_reg_desc);
>
>         add_pid_to_program(prg, pid);
> diff --git a/tests/fate/demux.mak b/tests/fate/demux.mak
> index ead5ad4b10..6e5e2eb81a 100644
> --- a/tests/fate/demux.mak
> +++ b/tests/fate/demux.mak
> @@ -158,7 +158,7 @@ FATE_SAMPLES_DEMUX-$(CONFIG_XWMA_DEMUXER) += fate-xwma-demux
> fate-xwma-demux: CMD = crc -i $(TARGET_SAMPLES)/xwma/ergon.xwma -c:a copy
>
> FATE_FFPROBE_DEMUX-$(CONFIG_MPEGTS_DEMUXER) += fate-ts-demux
> -fate-ts-demux: CMD = ffprobe_demux $(TARGET_SAMPLES)/ac3/mp3ac325-4864-small.ts
> +fate-ts-demux: CMD = ffprobe_demux $(TARGET_SAMPLES)/ac3/mp3ac325-4864-small.ts -reprobe_stream_if_pmt_es_stream_type_changes 1
>
> FATE_FFPROBE_DEMUX-$(CONFIG_MPEGTS_DEMUXER) += fate-ts-timed-id3-demux
> fate-ts-timed-id3-demux: CMD = ffprobe_demux $(TARGET_SAMPLES)/mpegts/id3.ts
> -- 
> 2.43.0
>
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