[FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Pavel Koshevoy]

Make midstream AVStream.codecpar updates optional and disabled
by default, so that avformat API clients can enable this feature
explicitly when they add support for midstream codec changes.
---
 doc/APIchanges          | 3 +++
 libavformat/avformat.h  | 2 ++
 libavformat/mpegts.c    | 4 +++-
 libavformat/version.h   | 4 ++--
 tests/ref/fate/ts-demux | 4 ++--
 5 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/doc/APIchanges b/doc/APIchanges
index 91710bb27d..43172fbcdd 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
 
 API changes, most recent first:
 
+2025-06-17 - xxxxxxxxxx - lavf 62.2.100 - avformat.h
+  Add AVFMT_FLAG_ALLOW_CODEC_CHANGES flag.
+
 2025-05-21 - xxxxxxxxxx - lavu 60.3.100 - avassert.h
   Add av_unreachable() and av_assume() macros.
 
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index b6c63e2237..2e5232c96d 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1436,6 +1436,8 @@ typedef struct AVFormatContext {
 #define AVFMT_FLAG_FAST_SEEK   0x80000 ///< Enable fast, but inaccurate seeks for some formats
 #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Add bitstream filters as requested by the muxer
 
+#define AVFMT_FLAG_ALLOW_CODEC_CHANGES 0x400000 ///< Allow AVStream.codecpar to be updated midstream if input changes (e.g. MPEG-TS ES stream_type changes)
+
     /**
      * Maximum number of bytes read from input in order to determine stream
      * properties. Used when reading the global header and in
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index deb69a0548..ed4ff580e5 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -2510,7 +2510,9 @@ 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->stream->flags & AVFMT_FLAG_ALLOW_CODEC_CHANGES))))
             mpegts_set_stream_info(st, pes, stream_type, prog_reg_desc);
 
         add_pid_to_program(prg, pid);
diff --git a/libavformat/version.h b/libavformat/version.h
index b32ddb3617..904e7f06aa 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,8 +31,8 @@
 
 #include "version_major.h"
 
-#define LIBAVFORMAT_VERSION_MINOR   1
-#define LIBAVFORMAT_VERSION_MICRO 101
+#define LIBAVFORMAT_VERSION_MINOR   2
+#define LIBAVFORMAT_VERSION_MICRO 100
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \
diff --git a/tests/ref/fate/ts-demux b/tests/ref/fate/ts-demux
index d56cc27937..6a830d0d99 100644
--- a/tests/ref/fate/ts-demux
+++ b/tests/ref/fate/ts-demux
@@ -24,6 +24,6 @@ packet|codec_type=video|stream_index=0|pts=3912686363|pts_time=43474.292922|dts=
 packet|codec_type=audio|stream_index=1|pts=3912644825|pts_time=43473.831389|dts=3912644825|dts_time=43473.831389|duration=2880|duration_time=0.032000|size=906|pos=474888|flags=K__|data_hash=CRC32:0893d398
 packet|codec_type=audio|stream_index=2|pts=3912645580|pts_time=43473.839778|dts=3912645580|dts_time=43473.839778|duration=2880|duration_time=0.032000|size=354|pos=491808|flags=K__|data_hash=CRC32:f5963fa6
 stream|index=0|codec_name=mpeg2video|profile=4|codec_type=video|codec_tag_string=[2][0][0][0]|codec_tag=0x0002|width=1280|height=720|coded_width=0|coded_height=0|has_b_frames=1|sample_aspect_ratio=1:1|display_aspect_ratio=16:9|pix_fmt=yuv420p|level=4|color_range=tv|color_space=unknown|color_transfer=unknown|color_primaries=unknown|chroma_location=left|field_order=progressive|refs=1|ts_id=32776|ts_packetsize=188|id=0x31|r_frame_rate=60000/1001|avg_frame_rate=60000/1001|time_base=1/90000|start_pts=3912669846|start_time=43474.109400|duration_ts=19519|duration=0.216878|bit_rate=15000000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=15|extradata_size=150|extradata_hash=CRC32:53134fa8|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|
 disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|side_datum/cpb_properties:side_data_type=CPB properties|side_datum/cpb_properties:max_bitrate=15000000|side_datum/cpb_properties:min_bitrate=0|side_datum/cpb_properties:avg_bitrate=0|side_datum/cpb_properties:buffer_size=9781248|side_datum/cpb_properties:vbv_delay=-1
-stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|
 disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
-stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|dis
 position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
+stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|
 disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
+stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|dis
 position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
 format|filename=mp3ac325-4864-small.ts|nb_streams=3|nb_programs=1|nb_stream_groups=0|format_name=mpegts|start_time=43473.703389|duration=0.622889|size=512000|bit_rate=6575810|probe_score=50
-- 
2.43.0

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Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Scott Theisen]

On 2025/06/29 23:55, Pavel Koshevoy wrote:
> Make midstream AVStream.codecpar updates optional and disabled
> by default, so that avformat API clients can enable this feature
> explicitly when they add support for midstream codec changes.

Is this signaled in any way or is the client expected to check if 
codecpar has changed?

I ask because MythTV added checking and a callback for streams changing 
between PMT versions, including adding or removing streams.

Thanks,

Scott Theisen

> ---
>   doc/APIchanges          | 3 +++
>   libavformat/avformat.h  | 2 ++
>   libavformat/mpegts.c    | 4 +++-
>   libavformat/version.h   | 4 ++--
>   tests/ref/fate/ts-demux | 4 ++--
>   5 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index 91710bb27d..43172fbcdd 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
>   
>   API changes, most recent first:
>   
> +2025-06-17 - xxxxxxxxxx - lavf 62.2.100 - avformat.h
> +  Add AVFMT_FLAG_ALLOW_CODEC_CHANGES flag.
> +
>   2025-05-21 - xxxxxxxxxx - lavu 60.3.100 - avassert.h
>     Add av_unreachable() and av_assume() macros.
>   
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index b6c63e2237..2e5232c96d 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -1436,6 +1436,8 @@ typedef struct AVFormatContext {
>   #define AVFMT_FLAG_FAST_SEEK   0x80000 ///< Enable fast, but inaccurate seeks for some formats
>   #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Add bitstream filters as requested by the muxer
>   
> +#define AVFMT_FLAG_ALLOW_CODEC_CHANGES 0x400000 ///< Allow AVStream.codecpar to be updated midstream if input changes (e.g. MPEG-TS ES stream_type changes)
> +
>       /**
>        * Maximum number of bytes read from input in order to determine stream
>        * properties. Used when reading the global header and in
> diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> index deb69a0548..ed4ff580e5 100644
> --- a/libavformat/mpegts.c
> +++ b/libavformat/mpegts.c
> @@ -2510,7 +2510,9 @@ 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->stream->flags & AVFMT_FLAG_ALLOW_CODEC_CHANGES))))
>               mpegts_set_stream_info(st, pes, stream_type, prog_reg_desc);
>   
>           add_pid_to_program(prg, pid);
> diff --git a/libavformat/version.h b/libavformat/version.h
> index b32ddb3617..904e7f06aa 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -31,8 +31,8 @@
>   
>   #include "version_major.h"
>   
> -#define LIBAVFORMAT_VERSION_MINOR   1
> -#define LIBAVFORMAT_VERSION_MICRO 101
> +#define LIBAVFORMAT_VERSION_MINOR   2
> +#define LIBAVFORMAT_VERSION_MICRO 100
>   
>   #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
>                                                  LIBAVFORMAT_VERSION_MINOR, \
> diff --git a/tests/ref/fate/ts-demux b/tests/ref/fate/ts-demux
> index d56cc27937..6a830d0d99 100644
> --- a/tests/ref/fate/ts-demux
> +++ b/tests/ref/fate/ts-demux
> @@ -24,6 +24,6 @@ packet|codec_type=video|stream_index=0|pts=3912686363|pts_time=43474.292922|dts=
>   packet|codec_type=audio|stream_index=1|pts=3912644825|pts_time=43473.831389|dts=3912644825|dts_time=43473.831389|duration=2880|duration_time=0.032000|size=906|pos=474888|flags=K__|data_hash=CRC32:0893d398
>   packet|codec_type=audio|stream_index=2|pts=3912645580|pts_time=43473.839778|dts=3912645580|dts_time=43473.839778|duration=2880|duration_time=0.032000|size=354|pos=491808|flags=K__|data_hash=CRC32:f5963fa6
>   stream|index=0|codec_name=mpeg2video|profile=4|codec_type=video|codec_tag_string=[2][0][0][0]|codec_tag=0x0002|width=1280|height=720|coded_width=0|coded_height=0|has_b_frames=1|sample_aspect_ratio=1:1|display_aspect_ratio=16:9|pix_fmt=yuv420p|level=4|color_range=tv|color_space=unknown|color_transfer=unknown|color_primaries=unknown|chroma_location=left|field_order=progressive|refs=1|ts_id=32776|ts_packetsize=188|id=0x31|r_frame_rate=60000/1001|avg_frame_rate=60000/1001|time_base=1/90000|start_pts=3912669846|start_time=43474.109400|duration_ts=19519|duration=0.216878|bit_rate=15000000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=15|extradata_size=150|extradata_hash=CRC32:53134fa8|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic
 =0|
>   disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|side_datum/cpb_properties:side_data_type=CPB properties|side_datum/cpb_properties:max_bitrate=15000000|side_datum/cpb_properties:min_bitrate=0|side_datum/cpb_properties:avg_bitrate=0|side_datum/cpb_properties:buffer_size=9781248|side_datum/cpb_properties:vbv_delay=-1
> -stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=
 0|
>   disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
> -stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|d
 is
>   position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
> +stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=
 0|
>   disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
> +stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|d
 is
>   position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
>   format|filename=mp3ac325-4864-small.ts|nb_streams=3|nb_programs=1|nb_stream_groups=0|format_name=mpegts|start_time=43473.703389|duration=0.622889|size=512000|bit_rate=6575810|probe_score=50

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Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Pavel Koshevoy]

On Mon, Jun 30, 2025 at 3:46 PM Scott Theisen <
scott.the.elm-at-gmail.com@ffmpeg.org> wrote:

> On 2025/06/29 23:55, Pavel Koshevoy wrote:
> > Make midstream AVStream.codecpar updates optional and disabled
> > by default, so that avformat API clients can enable this feature
> > explicitly when they add support for midstream codec changes.
>
> Is this signaled in any way or is the client expected to check if
> codecpar has changed?
>

The client is expected to check codecpar for changes ...
I've described it a bit more here
https://ffmpeg.org/pipermail/ffmpeg-devel/2025-June/344921.html



>
> I ask because MythTV added checking and a callback for streams changing
> between PMT versions, including adding or removing streams.
>
>
In my code (outside ffmpeg) I've also added a similar mechanism.
BTW, in mpeg-ts captures that I have the PMT version doesn't always change,
even when there are significant changes in the program structure.




> Thanks,
>
> Scott Theisen
>
> > ---
> >   doc/APIchanges          | 3 +++
> >   libavformat/avformat.h  | 2 ++
> >   libavformat/mpegts.c    | 4 +++-
> >   libavformat/version.h   | 4 ++--
> >   tests/ref/fate/ts-demux | 4 ++--
> >   5 files changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/doc/APIchanges b/doc/APIchanges
> > index 91710bb27d..43172fbcdd 100644
> > --- a/doc/APIchanges
> > +++ b/doc/APIchanges
> > @@ -2,6 +2,9 @@ The last version increases of all libraries were on
> 2025-03-28
> >
> >   API changes, most recent first:
> >
> > +2025-06-17 - xxxxxxxxxx - lavf 62.2.100 - avformat.h
> > +  Add AVFMT_FLAG_ALLOW_CODEC_CHANGES flag.
> > +
> >   2025-05-21 - xxxxxxxxxx - lavu 60.3.100 - avassert.h
> >     Add av_unreachable() and av_assume() macros.
> >
> > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> > index b6c63e2237..2e5232c96d 100644
> > --- a/libavformat/avformat.h
> > +++ b/libavformat/avformat.h
> > @@ -1436,6 +1436,8 @@ typedef struct AVFormatContext {
> >   #define AVFMT_FLAG_FAST_SEEK   0x80000 ///< Enable fast, but
> inaccurate seeks for some formats
> >   #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Add bitstream filters as
> requested by the muxer
> >
> > +#define AVFMT_FLAG_ALLOW_CODEC_CHANGES 0x400000 ///< Allow
> AVStream.codecpar to be updated midstream if input changes (e.g. MPEG-TS ES
> stream_type changes)
> > +
> >       /**
> >        * Maximum number of bytes read from input in order to determine
> stream
> >        * properties. Used when reading the global header and in
> > diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> > index deb69a0548..ed4ff580e5 100644
> > --- a/libavformat/mpegts.c
> > +++ b/libavformat/mpegts.c
> > @@ -2510,7 +2510,9 @@ 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->stream->flags &
> AVFMT_FLAG_ALLOW_CODEC_CHANGES))))
> >               mpegts_set_stream_info(st, pes, stream_type,
> prog_reg_desc);
> >
> >           add_pid_to_program(prg, pid);
> > diff --git a/libavformat/version.h b/libavformat/version.h
> > index b32ddb3617..904e7f06aa 100644
> > --- a/libavformat/version.h
> > +++ b/libavformat/version.h
> > @@ -31,8 +31,8 @@
> >
> >   #include "version_major.h"
> >
> > -#define LIBAVFORMAT_VERSION_MINOR   1
> > -#define LIBAVFORMAT_VERSION_MICRO 101
> > +#define LIBAVFORMAT_VERSION_MINOR   2
> > +#define LIBAVFORMAT_VERSION_MICRO 100
> >
> >   #define LIBAVFORMAT_VERSION_INT
> AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> >
> LIBAVFORMAT_VERSION_MINOR, \
> > diff --git a/tests/ref/fate/ts-demux b/tests/ref/fate/ts-demux
> > index d56cc27937..6a830d0d99 100644
> > --- a/tests/ref/fate/ts-demux
> > +++ b/tests/ref/fate/ts-demux
> > @@ -24,6 +24,6 @@
> packet|codec_type=video|stream_index=0|pts=3912686363|pts_time=43474.292922|dts=
> >
>  packet|codec_type=audio|stream_index=1|pts=3912644825|pts_time=43473.831389|dts=3912644825|dts_time=43473.831389|duration=2880|duration_time=0.032000|size=906|pos=474888|flags=K__|data_hash=CRC32:0893d398
> >
>  packet|codec_type=audio|stream_index=2|pts=3912645580|pts_time=43473.839778|dts=3912645580|dts_time=43473.839778|duration=2880|duration_time=0.032000|size=354|pos=491808|flags=K__|data_hash=CRC32:f5963fa6
> >
>  stream|index=0|codec_name=mpeg2video|profile=4|codec_type=video|codec_tag_string=[2][0][0][0]|codec_tag=0x0002|width=1280|height=720|coded_width=0|coded_height=0|has_b_frames=1|sample_aspect_ratio=1:1|display_aspect_ratio=16:9|pix_fmt=yuv420p|level=4|color_range=tv|color_space=unknown|color_transfer=unknown|color_primaries=unknown|chroma_location=left|field_order=progressive|refs=1|ts_id=32776|ts_packetsize=188|id=0x31|r_frame_rate=60000/1001|avg_frame_rate=60000/1001|time_base=1/90000|start_pts=3912669846|start_time=43474.109400|duration_ts=19519|duration=0.216878|bit_rate=15000000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=15|extradata_size=150|extradata_hash=CRC32:53134fa8|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic
>  =0|
> >
>  disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|side_datum/cpb_properties:side_data_type=CPB
> properties|side_datum/cpb_properties:max_bitrate=15000000|side_datum/cpb_properties:min_bitrate=0|side_datum/cpb_properties:avg_bitrate=0|side_datum/cpb_properties:buffer_size=9781248|side_datum/cpb_properties:vbv_delay=-1
> >
> -stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=
>  0|
> >
>  disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
> >
> -stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[6][0][0][0]|codec_tag=0x0006|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|d
>  is
> >
>  position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
> >
> +stream|index=1|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=6|channel_layout=5.1(side)|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x34|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912633305|start_time=43473.703389|duration_ts=14400|duration=0.160000|bit_rate=384000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=
>  0|
> >
>  disposition:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=eng
> >
> +stream|index=2|codec_name=ac3|profile=unknown|codec_type=audio|codec_tag_string=[4][0][0][0]|codec_tag=0x0004|sample_fmt=fltp|sample_rate=48000|channels=2|channel_layout=stereo|bits_per_sample=0|initial_padding=0|dmix_mode=0|ltrt_cmixlev=0.000000|ltrt_surmixlev=0.000000|loro_cmixlev=0.000000|loro_surmixlev=0.000000|ts_id=32776|ts_packetsize=188|id=0x35|r_frame_rate=0/0|avg_frame_rate=0/0|time_base=1/90000|start_pts=3912634060|start_time=43473.711778|duration_ts=14400|duration=0.160000|bit_rate=192000|max_bit_rate=N/A|bits_per_raw_sample=N/A|nb_frames=N/A|nb_read_frames=N/A|nb_read_packets=5|disposition:default=0|disposition:dub=0|disposition:original=0|disposition:comment=0|disposition:lyrics=0|disposition:karaoke=0|disposition:forced=0|disposition:hearing_impaired=0|disposition:visual_impaired=0|disposition:clean_effects=0|disposition:attached_pic=0|disposition:timed_thumbnails=0|disposition:non_diegetic=0|disposition:captions=0|disposition:descriptions=0|disposition:metadata=0|d
>  is
> >
>  position:dependent=0|disposition:still_image=0|disposition:multilayer=0|tag:language=es
> >
>  format|filename=mp3ac325-4864-small.ts|nb_streams=3|nb_programs=1|nb_stream_groups=0|format_name=mpegts|start_time=43473.703389|duration=0.622889|size=512000|bit_rate=6575810|probe_score=50
>
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Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Michael Niedermayer]

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On Mon, Jun 30, 2025 at 07:32:36PM -0600, Pavel Koshevoy wrote:
> On Mon, Jun 30, 2025 at 3:46 PM Scott Theisen <
> scott.the.elm-at-gmail.com@ffmpeg.org> wrote:
> 
> > On 2025/06/29 23:55, Pavel Koshevoy wrote:
> > > Make midstream AVStream.codecpar updates optional and disabled
> > > by default, so that avformat API clients can enable this feature
> > > explicitly when they add support for midstream codec changes.
> >
> > Is this signaled in any way or is the client expected to check if
> > codecpar has changed?
> >
> 
> The client is expected to check codecpar for changes ...

What performance impact does this have ?

also how does this align with AV_PKT_DATA_NEW_EXTRADATA
and AV_PKT_DATA_PARAM_CHANGE ?

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire

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[-- Attachment #2: Type: text/plain, Size: 251 bytes --]

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Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Pavel Koshevoy]

On Mon, Jun 30, 2025, 21:46 Michael Niedermayer <michael@niedermayer.cc>
wrote:

> On Mon, Jun 30, 2025 at 07:32:36PM -0600, Pavel Koshevoy wrote:
> > On Mon, Jun 30, 2025 at 3:46 PM Scott Theisen <
> > scott.the.elm-at-gmail.com@ffmpeg.org> wrote:
> >
> > > On 2025/06/29 23:55, Pavel Koshevoy wrote:
> > > > Make midstream AVStream.codecpar updates optional and disabled
> > > > by default, so that avformat API clients can enable this feature
> > > > explicitly when they add support for midstream codec changes.
> > >
> > > Is this signaled in any way or is the client expected to check if
> > > codecpar has changed?
> > >
> >
> > The client is expected to check codecpar for changes ...
>
> What performance impact does this have ?
>

In my player?  None that I cared to measure



> also how does this align with AV_PKT_DATA_NEW_EXTRADATA
> and AV_PKT_DATA_PARAM_CHANGE ?
>

I don't know anything about them.



> thx
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No snowflake in an avalanche ever feels responsible. -- Voltaire
> _______________________________________________
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> ffmpeg-devel@ffmpeg.org
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Re: [FFmpeg-devel] [PATCH] avformat/mpegts: Add AVFMT_FLAG_ALLOW_CODEC_CHANGES (v2)

[Scott Theisen]

On 2025/06/30 21:32, Pavel Koshevoy wrote:
> On Mon, Jun 30, 2025 at 3:46 PM Scott Theisen <
> scott.the.elm-at-gmail.com@ffmpeg.org> wrote:
>
>> On 2025/06/29 23:55, Pavel Koshevoy wrote:
>>> Make midstream AVStream.codecpar updates optional and disabled
>>> by default, so that avformat API clients can enable this feature
>>> explicitly when they add support for midstream codec changes.
>> Is this signaled in any way or is the client expected to check if
>> codecpar has changed?
>>
> The client is expected to check codecpar for changes ...
> I've described it a bit more here
> https://ffmpeg.org/pipermail/ffmpeg-devel/2025-June/344921.html
>
>
>
>> I ask because MythTV added checking and a callback for streams changing
>> between PMT versions, including adding or removing streams.
>>
>>
> In my code (outside ffmpeg) I've also added a similar mechanism.
> BTW, in mpeg-ts captures that I have the PMT version doesn't always change,
> even when there are significant changes in the program structure.

If the PMT version_number is not incremented, that doesn't comply with 
the standard ("The version number shall be incremented by 1 modulo 32 
when a change in the information carried within the section occurs." 
ISO/IEC 13818-1:2021 §2.4.4.10 Semantic definition of fields in 
transport stream program map section).

Since the CRC would be different, the non-compliant PMT is parsed and 
used (see skip_identical() in mpegts.c).

I had tried to just check the version_number (and 
current_next_indicator), but the Blu-ray for Rio (2011) has a new PMT 
version_number for (I think) every frame, which broke playback of that 
Blu-ray in MythTV since the decoder was resetting every frame, so we had 
to revert back to comparing the PMT data (ignoring the descriptors). 
https://github.com/MythTV/mythtv/commit/616074a0a5f4fa9ad7241e673d6693cbd7b5e310

Regards,

Scott Theisen
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