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 +++
doc/formats.texi | 5 +++++
libavformat/avformat.h | 2 ++
libavformat/mpegts.c | 4 +++-
libavformat/options_table.h | 1 +
libavformat/version.h | 2 +-
tests/fate/demux.mak | 2 +-
7 files changed, 16 insertions(+), 3 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/doc/formats.texi b/doc/formats.texi
index 876a9e92b3..5a0d070247 100644
--- a/doc/formats.texi
+++ b/doc/formats.texi
@@ -39,6 +39,11 @@ Set format flags. Some are implemented for a limited number
of formats.
Possible values for input files:
@table @samp
+@item allow_codec_changes
+Allow AVStream.codecpar to change midstream if input changes
+(for example when MPEG-TS ES stream_type changes).
+This is disabled by default, because most clients of avformat API
+do not support random midstream codec changes.
@item discardcorrupt
Discard corrupted packets.
@item fastseek
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/options_table.h b/libavformat/options_table.h
index e2e690fd2a..811dd342cc 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -50,6 +50,7 @@ static const AVOption avformat_options[] = {
{"sortdts", "try to interleave outputted packets by dts", 0,
AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_SORT_DTS }, INT_MIN, INT_MAX, D, .unit =
"fflags"},
{"fastseek", "fast but inaccurate seeks", 0, AV_OPT_TYPE_CONST, {.i64 =
AVFMT_FLAG_FAST_SEEK }, INT_MIN, INT_MAX, D, .unit = "fflags"},
{"nobuffer", "reduce the latency introduced by optional buffering", 0,
AV_OPT_TYPE_CONST, {.i64 = AVFMT_FLAG_NOBUFFER }, 0, INT_MAX, D, .unit =
"fflags"},
+{"allow_codec_changes", "allow AVStream.codecpar to change at runtime if input
changes", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_ALLOW_CODEC_CHANGES }, 0,
0, D, .unit = "fflags" },
{"bitexact", "do not write random/volatile data", 0, AV_OPT_TYPE_CONST, { .i64
= AVFMT_FLAG_BITEXACT }, 0, 0, E, .unit = "fflags" },
{"autobsf", "add needed bsfs automatically", 0, AV_OPT_TYPE_CONST, { .i64 =
AVFMT_FLAG_AUTO_BSF }, 0, 0, E, .unit = "fflags" },
{"seek2any", "allow seeking to non-keyframes on demuxer level when supported",
OFFSET(seek2any), AV_OPT_TYPE_BOOL, {.i64 = 0 }, 0, 1, D},
diff --git a/libavformat/version.h b/libavformat/version.h
index a7c80dc564..904e7f06aa 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,7 +31,7 @@
#include "version_major.h"
-#define LIBAVFORMAT_VERSION_MINOR 1
+#define LIBAVFORMAT_VERSION_MINOR 2
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
diff --git a/tests/fate/demux.mak b/tests/fate/demux.mak
index ead5ad4b10..e293a00dc0 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
$(TARGET_SAMPLES)/ac3/mp3ac325-4864-small.ts -fflags +allow_codec_changes
FATE_FFPROBE_DEMUX-$(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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