pan audiofilter regression

[Jose Peirote]

Summary of the bug:
The ticket #10168 is not fixed.

ffmpeg -i "8w341.wav" -af "pan=FL+FR+FC+LFE|c0=c0|c1=c1|c2=c2|c3=c3" -acodec pcm_s16le "8w341_51.wav"
ffmpeg version N-109781-g25f31929b6-20230209 Copyright (c) 2000-2023 the FFmpeg developers

libavutil 57. 44.100 / 57. 44.100
libavcodec 59. 63.100 / 59. 63.100

...
Input #0, wav, from '8w341.wav':

Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 7.1, s16, 6144 kb/s

[Parsed_pan_0 @ 000001100b6c98c0] Pure channel mapping detected: 0 1 2 3
Output #0, wav, to '8w341_51.wav':

Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 3.1, s16, 3072 kb/s

The output have a correct channelmask FL+FR+FC+LFE but now with a different channel remix than before (#10168). See the new image.

Instead c0=c0|c1=c1|c2=c2|c3=c3, do a renormalize?:
FL'= FL
FR'= 0.59*FL + 0.41*FR
FC'= 0.41*FC
LFE'=0.41*LFE

[Balling]

Fixed in 4561232b1a36b7f8532c7939e4a508734053f6f0