* [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP
@ 2023-02-07 20:59 Jan Ekström
2023-02-09 10:08 ` Martin Storsjö
0 siblings, 1 reply; 4+ messages in thread
From: Jan Ekström @ 2023-02-07 20:59 UTC (permalink / raw)
To: ffmpeg-devel
ISOBMFF (14496-12) made this field ('channelcount') in the
AudioSampleEntry structure non-template¹ somewhere before the
release of the 2022 edition. As for ETSI TS 126 244 AKA 3GPP
file format (V16.1.0, 2020-10), it does not seem contain any
references limiting the channelcount entry in AudioSampleEntry
or in its own definition of EVSSampleEntry.
fate-mov-mp4-chapters test had to be adjusted as it output a
mono vorbis stream, which would now be properly marked as such
in the container.
1: As per 14496-12:
Fields shown as “template” in the box descriptions are fields
which are coded with a default value unless a derived
specification defines their use and permits writers to use
other values than the default.
---
libavformat/movenc.c | 8 +-------
tests/ref/fate/mov-mp4-chapters | 2 +-
2 files changed, 2 insertions(+), 8 deletions(-)
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 8d31317838..f0e218e7b7 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1241,13 +1241,7 @@ static int mov_write_audio_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContex
avio_wb16(pb, 16);
avio_wb16(pb, track->audio_vbr ? -2 : 0); /* compression ID */
} else { /* reserved for mp4/3gp */
- if (track->par->codec_id == AV_CODEC_ID_FLAC ||
- track->par->codec_id == AV_CODEC_ID_ALAC ||
- track->par->codec_id == AV_CODEC_ID_OPUS) {
- avio_wb16(pb, track->par->ch_layout.nb_channels);
- } else {
- avio_wb16(pb, 2);
- }
+ avio_wb16(pb, track->par->ch_layout.nb_channels);
if (track->par->codec_id == AV_CODEC_ID_FLAC ||
track->par->codec_id == AV_CODEC_ID_ALAC) {
avio_wb16(pb, track->par->bits_per_raw_sample);
diff --git a/tests/ref/fate/mov-mp4-chapters b/tests/ref/fate/mov-mp4-chapters
index 34f84de1b1..75cd3b3438 100644
--- a/tests/ref/fate/mov-mp4-chapters
+++ b/tests/ref/fate/mov-mp4-chapters
@@ -1,4 +1,4 @@
-1fd844c2f5bf77c3344e88e30ad994e1 *tests/data/fate/mov-mp4-chapters.mp4
+7b6aaa99c86fa1f5abfc9f242abcfffa *tests/data/fate/mov-mp4-chapters.mp4
111248 tests/data/fate/mov-mp4-chapters.mp4
#extradata 0: 3469, 0xc6769ddc
#tb 0: 1/44100
--
2.39.1
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP
2023-02-07 20:59 [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP Jan Ekström
@ 2023-02-09 10:08 ` Martin Storsjö
2023-02-09 19:24 ` Jan Ekström
0 siblings, 1 reply; 4+ messages in thread
From: Martin Storsjö @ 2023-02-09 10:08 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On Tue, 7 Feb 2023, Jan Ekström wrote:
> ISOBMFF (14496-12) made this field ('channelcount') in the
> AudioSampleEntry structure non-template¹ somewhere before the
> release of the 2022 edition. As for ETSI TS 126 244 AKA 3GPP
> file format (V16.1.0, 2020-10), it does not seem contain any
> references limiting the channelcount entry in AudioSampleEntry
> or in its own definition of EVSSampleEntry.
>
> fate-mov-mp4-chapters test had to be adjusted as it output a
> mono vorbis stream, which would now be properly marked as such
> in the container.
>
> 1: As per 14496-12:
> Fields shown as “template” in the box descriptions are fields
> which are coded with a default value unless a derived
> specification defines their use and permits writers to use
> other values than the default.
> ---
> libavformat/movenc.c | 8 +-------
> tests/ref/fate/mov-mp4-chapters | 2 +-
> 2 files changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> index 8d31317838..f0e218e7b7 100644
> --- a/libavformat/movenc.c
> +++ b/libavformat/movenc.c
> @@ -1241,13 +1241,7 @@ static int mov_write_audio_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContex
> avio_wb16(pb, 16);
> avio_wb16(pb, track->audio_vbr ? -2 : 0); /* compression ID */
> } else { /* reserved for mp4/3gp */
> - if (track->par->codec_id == AV_CODEC_ID_FLAC ||
> - track->par->codec_id == AV_CODEC_ID_ALAC ||
> - track->par->codec_id == AV_CODEC_ID_OPUS) {
> - avio_wb16(pb, track->par->ch_layout.nb_channels);
> - } else {
> - avio_wb16(pb, 2);
> - }
> + avio_wb16(pb, track->par->ch_layout.nb_channels);
> if (track->par->codec_id == AV_CODEC_ID_FLAC ||
> track->par->codec_id == AV_CODEC_ID_ALAC) {
> avio_wb16(pb, track->par->bits_per_raw_sample);
This looks reasonable to me. I didn't follow the references in the commit
message, but it sounds plausible and probably correct to me.
// Martin
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP
2023-02-09 10:08 ` Martin Storsjö
@ 2023-02-09 19:24 ` Jan Ekström
2023-02-14 19:27 ` Jan Ekström
0 siblings, 1 reply; 4+ messages in thread
From: Jan Ekström @ 2023-02-09 19:24 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On Thu, Feb 9, 2023 at 12:08 PM Martin Storsjö <martin@martin.st> wrote:
>
> This looks reasonable to me. I didn't follow the references in the commit
> message, but it sounds plausible and probably correct to me.
>
For the record, due to dumb ISO/IEC rule changes regarding how
specifications need to be authorized to be free after 2015, it's
relatively hard to verify the 14496-12 part.
The last version of 14496-12 that was freely available (2015) defined
channelcount in AudioSampleEntry as follows:
template unsigned int(16) channelcount = 2;
Meanwhile the latest 2022 edition defines the related structure(s) as follows:
class AudioSampleEntry(codingname) extends SampleEntry (codingname) {
const unsigned int(32)[2] reserved = 0;
unsigned int(16) channelcount;
template unsigned int(16) samplesize = 16;
unsigned int(16) pre_defined = 0;
const unsigned int(16) reserved = 0 ;
template unsigned int(32) samplerate = { default samplerate of media} << 16;
// optional boxes follow
Box (); // further boxes as needed
ChannelLayout();
DownMixInstructions() [];
DRCCoefficientsBasic() [];
DRCInstructionsBasic() [];
DRCCoefficientsUniDRC() [];
DRCInstructionsUniDRC() [];
// we permit only one DRC Extension box:
UniDrcConfigExtension();
// optional boxes follow
SamplingRateBox();
ChannelLayout();
}
aligned(8) class SamplingRateBox extends FullBox('srat') {
unsigned int(32) sampling_rate;
}
class AudioSampleEntryV1(codingname) extends SampleEntry (codingname) {
unsigned int(16) entry_version; // shall be 1,
// and shall be in an stsd with version ==1
const unsigned int(16)[3] reserved = 0;
template unsigned int(16) channelcount; // shall be correct
template unsigned int(16) samplesize = 16;
unsigned int(16) pre_defined = 0;
const unsigned int(16) reserved = 0 ;
template unsigned int(32) samplerate = 1<<16;
// optional boxes follow
SamplingRateBox();
Box (); // further boxes as needed
ChannelLayout();
DownMixInstructions() [];
DRCCoefficientsBasic() [];
DRCInstructionsBasic() [];
DRCCoefficientsUniDRC() [];
DRCInstructionsUniDRC() [];
// we permit only one DRC Extension box:
UniDrcConfigExtension();
// optional boxes follow
ChannelLayout();
}
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP
2023-02-09 19:24 ` Jan Ekström
@ 2023-02-14 19:27 ` Jan Ekström
0 siblings, 0 replies; 4+ messages in thread
From: Jan Ekström @ 2023-02-14 19:27 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On Thu, Feb 9, 2023 at 9:24 PM Jan Ekström <jeebjp@gmail.com> wrote:
>
> On Thu, Feb 9, 2023 at 12:08 PM Martin Storsjö <martin@martin.st> wrote:
> >
> > This looks reasonable to me. I didn't follow the references in the commit
> > message, but it sounds plausible and probably correct to me.
> >
>
> For the record, due to dumb ISO/IEC rule changes regarding how
> specifications need to be authorized to be free after 2015, it's
> relatively hard to verify the 14496-12 part.
>
> The last version of 14496-12 that was freely available (2015) defined
> channelcount in AudioSampleEntry as follows:
>
> template unsigned int(16) channelcount = 2;
>
> Meanwhile the latest 2022 edition defines the related structure(s) as follows:
>
> class AudioSampleEntry(codingname) extends SampleEntry (codingname) {
> const unsigned int(32)[2] reserved = 0;
> unsigned int(16) channelcount;
> template unsigned int(16) samplesize = 16;
> unsigned int(16) pre_defined = 0;
> const unsigned int(16) reserved = 0 ;
> template unsigned int(32) samplerate = { default samplerate of media} << 16;
> // optional boxes follow
> Box (); // further boxes as needed
> ChannelLayout();
> DownMixInstructions() [];
> DRCCoefficientsBasic() [];
> DRCInstructionsBasic() [];
> DRCCoefficientsUniDRC() [];
> DRCInstructionsUniDRC() [];
> // we permit only one DRC Extension box:
> UniDrcConfigExtension();
> // optional boxes follow
> SamplingRateBox();
> ChannelLayout();
> }
>
> aligned(8) class SamplingRateBox extends FullBox('srat') {
> unsigned int(32) sampling_rate;
> }
>
> class AudioSampleEntryV1(codingname) extends SampleEntry (codingname) {
> unsigned int(16) entry_version; // shall be 1,
> // and shall be in an stsd with version ==1
> const unsigned int(16)[3] reserved = 0;
> template unsigned int(16) channelcount; // shall be correct
> template unsigned int(16) samplesize = 16;
> unsigned int(16) pre_defined = 0;
> const unsigned int(16) reserved = 0 ;
> template unsigned int(32) samplerate = 1<<16;
> // optional boxes follow
> SamplingRateBox();
> Box (); // further boxes as needed
> ChannelLayout();
> DownMixInstructions() [];
> DRCCoefficientsBasic() [];
> DRCInstructionsBasic() [];
> DRCCoefficientsUniDRC() [];
> DRCInstructionsUniDRC() [];
> // we permit only one DRC Extension box:
> UniDrcConfigExtension();
> // optional boxes follow
> ChannelLayout();
> }
Applied to master as 02ddfeadbee52c1ad8c023a93594a8cb957e11db .
Jan
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-02-14 19:27 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-02-07 20:59 [FFmpeg-devel] [PATCH] avformat/movenc: allow writing out channel count in MP4 and 3GP Jan Ekström
2023-02-09 10:08 ` Martin Storsjö
2023-02-09 19:24 ` Jan Ekström
2023-02-14 19:27 ` Jan Ekström
Git Inbox Mirror of the ffmpeg-devel mailing list - see https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
This inbox may be cloned and mirrored by anyone:
git clone --mirror https://master.gitmailbox.com/ffmpegdev/0 ffmpegdev/git/0.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 ffmpegdev ffmpegdev/ https://master.gitmailbox.com/ffmpegdev \
ffmpegdev@gitmailbox.com
public-inbox-index ffmpegdev
Example config snippet for mirrors.
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git