* [FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: gracefully ignore mismatching channel layouts for -channel_layout option
@ 2024-06-03 21:48 Marton Balint
2024-06-05 8:41 ` Anton Khirnov
0 siblings, 1 reply; 3+ messages in thread
From: Marton Balint @ 2024-06-03 21:48 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Marton Balint
The very old behaviour of -channel_layout was to simply warn the user about
channel layouts which does not have a matching channel count, and ignore them,
instead of reporting an error.
The recent fix re-added support for overriding -channel_layout, but it rejected
mismatching layouts. There is no easy way for the user to specify a channel
layout only for streams with matching number of channels, so this patch
restores the very old behaviour of ignoring mismatching layouts. See the
discussion in ticket #11016.
Signed-off-by: Marton Balint <cus@passwd.hu>
---
fftools/ffmpeg_demux.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
index 1ca8d804ae..2e77210237 100644
--- a/fftools/ffmpeg_demux.c
+++ b/fftools/ffmpeg_demux.c
@@ -1399,13 +1399,14 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st)
av_channel_layout_uninit(&par->ch_layout);
par->ch_layout = ch_layout;
} else {
- av_log(ist, AV_LOG_ERROR,
- "Specified channel layout '%s' has %d channels, but input has %d channels.\n",
+ av_log(ist, AV_LOG_WARNING,
+ "Specified channel layout '%s' has %d channels, but input has %d channels. Ignoring specified layout.\n",
ch_layout_str, ch_layout.nb_channels, par->ch_layout.nb_channels);
av_channel_layout_uninit(&ch_layout);
- return AVERROR(EINVAL);
+ ch_layout_str = NULL;
}
- } else {
+ }
+ if (!ch_layout_str) {
int guess_layout_max = INT_MAX;
MATCH_PER_STREAM_OPT(guess_layout_max, i, guess_layout_max, ic, st);
guess_input_channel_layout(ist, par, guess_layout_max);
--
2.35.3
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: gracefully ignore mismatching channel layouts for -channel_layout option
2024-06-03 21:48 [FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: gracefully ignore mismatching channel layouts for -channel_layout option Marton Balint
@ 2024-06-05 8:41 ` Anton Khirnov
2024-06-10 19:23 ` Marton Balint
0 siblings, 1 reply; 3+ messages in thread
From: Anton Khirnov @ 2024-06-05 8:41 UTC (permalink / raw)
To: FFmpeg development discussions and patches; +Cc: Marton Balint
Quoting Marton Balint (2024-06-03 23:48:47)
> The very old behaviour of -channel_layout was to simply warn the user about
> channel layouts which does not have a matching channel count, and ignore them,
> instead of reporting an error.
>
> The recent fix re-added support for overriding -channel_layout, but it rejected
> mismatching layouts. There is no easy way for the user to specify a channel
> layout only for streams with matching number of channels, so this patch
> restores the very old behaviour of ignoring mismatching layouts. See the
> discussion in ticket #11016.
I'm ambivalent about this. On one hand it probably doesn't hurt, for now
at least, on the other it seems quite ad-hoc. Previously it worked this
way mostly by accident, whereas if we now restore this behaviour
deliberately we'll be committing to supporting it for the foreseeable
future.
--
Anton Khirnov
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: gracefully ignore mismatching channel layouts for -channel_layout option
2024-06-05 8:41 ` Anton Khirnov
@ 2024-06-10 19:23 ` Marton Balint
0 siblings, 0 replies; 3+ messages in thread
From: Marton Balint @ 2024-06-10 19:23 UTC (permalink / raw)
To: FFmpeg development discussions and patches
On Wed, 5 Jun 2024, Anton Khirnov wrote:
> Quoting Marton Balint (2024-06-03 23:48:47)
>> The very old behaviour of -channel_layout was to simply warn the user about
>> channel layouts which does not have a matching channel count, and ignore them,
>> instead of reporting an error.
>>
>> The recent fix re-added support for overriding -channel_layout, but it rejected
>> mismatching layouts. There is no easy way for the user to specify a channel
>> layout only for streams with matching number of channels, so this patch
>> restores the very old behaviour of ignoring mismatching layouts. See the
>> discussion in ticket #11016.
>
> I'm ambivalent about this. On one hand it probably doesn't hurt, for now
> at least, on the other it seems quite ad-hoc. Previously it worked this
> way mostly by accident, whereas if we now restore this behaviour
> deliberately we'll be committing to supporting it for the foreseeable
> future.
>
Yeah, I am a bit unsure about it as well. What made me implement this is
that there is really no easy way I could think of to simulate the old
behaviour. An alternative idea might be to introduce a new option
"-try_channel_map" which only gives a warning.
Ideally if we could use a stream specifier something like
-channel_map:a:eval:eq(st.codecpar.ch_layout.nb_channels,1) mono
that should solve this in a generic way, but this requires massive new
features in the eval API and in the opt API as well.
Regards,
Marton
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-06-03 21:48 [FFmpeg-devel] [PATCH] fftools/ffmpeg_demux: gracefully ignore mismatching channel layouts for -channel_layout option Marton Balint
2024-06-05 8:41 ` Anton Khirnov
2024-06-10 19:23 ` Marton Balint
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