[FFmpeg-devel] [DEVEL][PATCH v2] ffmpeg: fix channel_layout bug on non-default layout

Michael Niedermayer michael at niedermayer.cc
Sun Nov 12 18:00:48 EET 2017


On Sat, Nov 11, 2017 at 02:15:25AM +0100, pkv.stream wrote:
> Le 11/11/2017 à 1:07 AM, Michael Niedermayer a écrit :
> >On Fri, Nov 10, 2017 at 10:27:48PM +0100, pkv.stream wrote:
> >>Le 10/11/2017 à 1:12 AM, Michael Niedermayer a écrit :
> >>>On Thu, Nov 09, 2017 at 09:37:33PM +0100, pkv.stream wrote:
> >>>>Hi Michael,
> >>>>
> >>>>>>  ffmpeg_opt.c |   11 ++++++++++-
> >>>>>>  1 file changed, 10 insertions(+), 1 deletion(-)
> >>>>>>2af07f4366efdfaf1018bb2ea29be672befe0823  0001-ffmpeg-fix-channel_layout-bug-on-non-default-layout.patch
> >>>>>> From 4ec55dc88923108132307b41300a1abddf32e6f7 Mon Sep 17 00:00:00 2001
> >>>>>>From: pkviet <pkv.stream at gmail.com>
> >>>>>>Date: Mon, 2 Oct 2017 11:14:31 +0200
> >>>>>>Subject: [PATCH] ffmpeg: fix channel_layout bug on non-default layout
> >>>>>>
> >>>>>>Fix for ticket 6706.
> >>>>>>The -channel_layout option was not working when the channel layout was not
> >>>>>>a default one (ex: for 4 channels, quad was interpreted as 4.0 which is
> >>>>>>the default layout for 4 channels; or octagonal interpreted as 7.1).
> >>>>>>This led to the spurious auto-insertion of an auto-resampler filter
> >>>>>>remapping the channels even if input and output had identical channel
> >>>>>>layouts.
> >>>>>>The fix operates by directly calling the channel layout if defined in
> >>>>>>options. If the layout is undefined, the default layout is selected as
> >>>>>>before the fix.
> >>>>>>---
> >>>>>>  ffmpeg_opt.c | 11 ++++++++++-
> >>>>>>  1 file changed, 10 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>>diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
> >>>>>>index 100fa76..cf5a63c 100644
> >>>>>>--- a/ffmpeg_opt.c
> >>>>>>+++ b/ffmpeg_opt.c
> >>>>>>@@ -1804,6 +1804,12 @@ static OutputStream *new_audio_stream(OptionsContext *o, AVFormatContext *oc, in
> >>>>>>          MATCH_PER_STREAM_OPT(audio_channels, i, audio_enc->channels, oc, st);
> >>>>>>+        AVDictionaryEntry *output_layout = av_dict_get(o->g->codec_opts,
> >>>>>>+                                                       "channel_layout",
> >>>>>>+                                                       NULL, AV_DICT_MATCH_CASE);
> >>>>>This doesnt look right
> >>>>>
> >>>>>not an issue of the patch as such but
> >>>>>why is the channel_layout option per file and not per stream?
> >>>>just my ignorance; do you mean this is not the right way to retrieve
> >>>>the channel_layout option from an audio stream ?
> >>>I think there is more buggy with how the channel_layout is handled
> >>>
> >>>try this:
> >>>./ffmpeg -i ~/videos/matrixbench_mpeg2.mpg -channel_layout 5 test.wav
> >>>and this:
> >>>./ffmpeg -i ~/videos/matrixbench_mpeg2.mpg -channel_layout:a 5 test.wav
> >>>
> >>>while it may appear that the are both working this is deceiving.
> >>>I think only the channel number gets actually used in the 2nd case
> >>>
> >>>Look at what your code with av_dict_get() reads.
> >>>It does not obtain the 5 in the 2nd case
> >>ok I fixed that by using the flag AV_DICT_IGNORE_SUFFIX ; now
> >>-channel_layout:a works as expected.
> >>I fixed also all the styling issues you spotted (mixed declarations,
> >>{} for if etc).
> >>
> >>Still not understanding your initial comment though :
> >>'why is the channel_layout option per file and not per stream?'
> >>
> >>do you mean o->g->codec_opts is not where I should retrieve the
> >>channel_layout ? if not where from ?
> >>
> >>Thanks
> >>
> >>>[...]
> >>>
> >>>
> >>>_______________________________________________
> >>>ffmpeg-devel mailing list
> >>>ffmpeg-devel at ffmpeg.org
> >>>http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>
> >>  ffmpeg_opt.c |   12 ++++++++++--
> >>  1 file changed, 10 insertions(+), 2 deletions(-)
> >>849898d28e989ffa5cc598c6fe4d43847b636132  0001-ffmpeg-fix-channel_layout-bug-on-non-default-layout.patch
> >> From 6d4f1c14135f9473b77e1c649d0e7bbaeba00a50 Mon Sep 17 00:00:00 2001
> >>From: pkviet <pkv.stream at gmail.com>
> >>Date: Mon, 2 Oct 2017 11:14:31 +0200
> >>Subject: [PATCH] ffmpeg: fix channel_layout bug on non-default layout
> >>
> >>Fix for ticket 6706.
> >>The -channel_layout option was not working when the channel layout was not
> >>a default one (ex: for 4 channels, quad was interpreted as 4.0 which is
> >>the default layout for 4 channels; or octagonal interpreted as 7.1).
> >>This led to the spurious auto-insertion of an auto-resampler filter
> >>remapping the channels even if input and output had identical channel
> >>layouts.
> >>The fix operates by directly calling the channel layout if defined in
> >>options. If the layout is undefined, the default layout is selected as
> >>before the fix.
> >>---
> >>  fftools/ffmpeg_opt.c | 12 ++++++++++--
> >>  1 file changed, 10 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> >>index ca6f10d..cb25d7b 100644
> >>--- a/fftools/ffmpeg_opt.c
> >>+++ b/fftools/ffmpeg_opt.c
> >>@@ -1785,6 +1785,7 @@ static OutputStream *new_audio_stream(OptionsContext *o, AVFormatContext *oc, in
> >>      AVStream *st;
> >>      OutputStream *ost;
> >>      AVCodecContext *audio_enc;
> >>+    AVDictionaryEntry *output_layout;
> >>      ost = new_output_stream(o, oc, AVMEDIA_TYPE_AUDIO, source_index);
> >>      st  = ost->st;
> >>@@ -1799,7 +1800,10 @@ static OutputStream *new_audio_stream(OptionsContext *o, AVFormatContext *oc, in
> >>          char *sample_fmt = NULL;
> >>          MATCH_PER_STREAM_OPT(audio_channels, i, audio_enc->channels, oc, st);
> >>-
> >>+        output_layout = av_dict_get(o->g->codec_opts,"channel_layout", NULL, AV_DICT_IGNORE_SUFFIX);
> >i didnt try but i assume
> >this would fail if there are 2 audio streams each with different
> >layout
> 
> ah ok, I understand now; thanks for elaborating.
> i tested with two output streams, it's not failing and working correctly.
> 
> ex: ffmpeg -channel_layout octagonal -i source.wav -c:a pcm_s16le
> -channel_layout octagonal out1.wav -c:a pcm_s16le -channel_layout
> quad out2.wav
> 
> (if I pick layout 0x5 as in your examples it fails because the
> rematrix is not supported, so this is expected behavior although
> failing; but with pan filter it eventually works)
> 
> Tested also with two source streams used for two ouputs. Working too.

have you tried with different layouts for each stream ?

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

Democracy is the form of government in which you can choose your dictator
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