[FFmpeg-devel] [PATCH] ffmpeg: Carry streamid as metadata key 'id'

[Michael Niedermayer]

On Mon, Apr 15, 2024 at 10:35:44AM +0200, Tomas Härdin wrote:
> lör 2024-04-13 klockan 01:25 +0200 skrev Michael Niedermayer:
> > On Fri, Apr 12, 2024 at 11:40:47AM +0200, Tomas Härdin wrote:
> > > This idea could be extended to other fields not presently
> > > considered to
> > > be metadata, that would be handy to treat as such.
> > > 
> > > I use the key "id" because ffprobe outputs id= for streamid.
> > > Another
> > > option could be to collect these types of metadata that go into
> > > AVStream fields under a namespace like FFMPEG: or AVSTREAM: or
> > > something, then delete all of them using AV_DICT_IGNORE_SUFFIX near
> > > the
> > > end of of_open() since they're for internal ffmpeg use.
> > > 
> > > The FATE change is just because av_dict() changes the order of
> > > things
> > > when elements are deleted.
> > > 
> > > /Tomas
> > 
> > >  fftools/ffmpeg_demux.c              |    5 +++
> > >  fftools/ffmpeg_mux_init.c           |   56
> > > ++++++++++++++++++++++++++----------
> > >  tests/ref/fate/matroska-stereo_mode |    6 +--
> > >  3 files changed, 49 insertions(+), 18 deletions(-)
> > > cd526b2292b6d7e3fb5739a04cf17fbe5f207f16  0001-ffmpeg-Carry-
> > > streamid-as-metadata-key-id.patch
> > > From 7799f1b2eb8ab02e58118565f3e889fbe0d568a7 Mon Sep 17 00:00:00
> > > 2001
> > > From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <git at haerdin.se>
> > > Date: Fri, 12 Apr 2024 10:34:12 +0200
> > > Subject: [PATCH] ffmpeg: Carry streamid as metadata key 'id'
> > > 
> > > This allows using -map_metadata and -metadata to copy/set streamids
> > > (PIDs).
> > > ---
> > >  fftools/ffmpeg_demux.c              |  5 +++
> > >  fftools/ffmpeg_mux_init.c           | 56 +++++++++++++++++++++----
> > > ----
> > >  tests/ref/fate/matroska-stereo_mode |  6 ++--
> > >  3 files changed, 49 insertions(+), 18 deletions(-)
> > 
> > breaks:
> > 
> > ./ffmpeg -i ~/videos/mm-short.mpg -vstats_file /tmp/vstats -bitexact
> > -map 0:1 -map 0:1 -map 0:2 -threads 6 -vcodec libx264 -vcodec libx264
> > -pass 1 -b:v:0 300k -b:v:1 900k -passlogfile:v:1 /tmp/video2 -
> > passlogfile:v:0 /tmp/video1 -t 1 -y -ab 128k  /tmp/x.ts
> > 
> > [mpegts @ 0x558d5e3b2140] Duplicate stream id 480
> 
> It's hardly strange if you map the same stream to the output twice that
> you get duplicate streamids

ok but asking for a stream to be mapped twice is a valid case.
Ideally FFmpeg should not fail, it should resolve all parameters
within what is valid.
It could fail if the user explcicitly asks for invalid parameters ...

thx

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

Does the universe only have a finite lifespan? No, its going to go on
forever, its just that you wont like living in it. -- Hiranya Peiri
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