Bug#1111314: simplescreenrecorder: audio recording fails with "Unsupported channel layout"

I am also affected by this bug, analyzed it using Claude. Below is a 
summary generated by Claude.

Cheers,
Armin




I can confirm this on Debian 13 (trixie) with simplescreenrecorder 
0.4.4-6 and FFmpeg 7.1.1 (libavcodec61).

The failure is not specific to AAC — every strict encoder is affected. 
With MP3 selected, libmp3lame gives a more explicit hint:

   [libmp3lame] Specified channel layout '2 channels' is not supported 
by the libmp3lame encoder
   [libmp3lame] Supported channel layouts: mono, stereo

Root cause: the new-API branch added by 1020-ffmpeg-7.patch sets

   codec_context->ch_layout.nb_channels = channels;
   codec_context->ch_layout.u.mask = (channels == 1) ? AV_CH_LAYOUT_MONO 
: AV_CH_LAYOUT_STEREO;

but leaves ch_layout.order at AV_CHANNEL_ORDER_UNSPEC. The encoders 
therefore see an unnamed "2 channels" layout instead of "stereo" and 
refuse to open.

Upstream already solves this. In src/AV/Output/AudioEncoder.cpp the 
SSR_USE_AV_CHANNEL_LAYOUT branch uses:

   av_channel_layout_default(&codec_context->ch_layout, channels);

This sets order/nb_channels/mask correctly and covers both FFmpeg 7 and 
8 in a single line. The cleanest fix is to make the Debian patch's #else 
branch match upstream instead of assigning the fields by hand.

Regarding the patch already attached to this report: it is functionally 
correct — av_channel_layout_from_mask() also produces a NATIVE-order 
layout, so it does fix the bug. It is just more elaborate than 
necessary; the single av_channel_layout_default() call above would be 
sufficient and matches upstream exactly.

I have verified the upstream code path; the only divergence is the 
version gate (upstream switches to the new API at libavcodec 59.24, the 
Debian patch at major >= 61), which is harmless on trixie.