[FFmpeg-devel] [PATCH] avfilter/buffersrc: fix overriding unknown channel layouts with negotiated one

[James Almer]

On 3/29/2024 7:01 PM, Marton Balint wrote:
> 
> 
> On Sat, 23 Mar 2024, Marton Balint wrote:
> 
>> Fixes ffplay playback of unknown layouts, when SDL directly supports 
>> the audio
>> format, such as:
>>
>> ffplay -f lavfi anullsrc=cl=2C,aformat=s16
>>
>> Without the patch, "Channel layout change is not supported" errors are
>> generated because buffersrc (unknown 2 channel) and buffersink (stereo)
>> negotiated a stereo layout, but the stereo layout was never stored in the
>> BufferSourceContext.
>>
>> This fixes a regression of 7251f909721a570726775acf61b2b9c28a950c76, 
>> but this
>> is more of a regression of the avfilter channel layout conversion
>> (1f96db959c1235bb7079d354e09914a0a2608f62).
>>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>> libavfilter/buffersrc.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavfilter/buffersrc.c b/libavfilter/buffersrc.c
>> index ddcd403785..fcae4f8e69 100644
>> --- a/libavfilter/buffersrc.c
>> +++ b/libavfilter/buffersrc.c
>> @@ -507,7 +507,7 @@ static int config_props(AVFilterLink *link)
>>         }
>>         break;
>>     case AVMEDIA_TYPE_AUDIO:
>> -        if (!c->ch_layout.nb_channels) {
>> +        if (!c->ch_layout.nb_channels || c->ch_layout.order == 
>> AV_CHANNEL_ORDER_UNSPEC) {
>>             int ret = av_channel_layout_copy(&c->ch_layout, 
>> &link->ch_layout);

Why is this the only field in the function where BufferSourceContext is 
the destination and the link is the source?

>>             if (ret < 0)
>>                 return ret;
> 
> Will apply and backport.
> 
> Regards,
> Marton
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