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.str...@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 finally got what you meant with the second case; I had not realized
that stream specifiers could be applied also to -channel_layout option.
thanks
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