[FFmpeg-user] FFMPEG sidechaincompress not working as it should?

[Paul B Mahol]

On 10/23/17, Frank @ Taapo <info at taapo.com> wrote:
> I have been trying to get sidechaining to work with FFMPEG, but my complex
> filter skills are lacking.
>
> I'm running two aif files into ffmpeg, hoping the voice would "duck" the
> background music when the voice-over is speaking. But I get an error with
> this command-line (on Windows, with latest FFMPEG binary):
>
> ffmpeg.exe -i temp_music.aif -i temp_voice.aif -filter_complex
> "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress=threshold=0.1:ratio=5[bg];
> [bg][mix]amerge[fin**al]" -map [final] final.mp3
>
> Everything decodes fine:
>
> ffmpeg version N-87353-g183fd30 Copyright (c) 2000-2017 the FFmpeg
> developers
>   built with gcc 7.2.0 (GCC)
>   configuration: --enable-gpl --enable-version3 --enable-cuda
> --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx
> --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig
> --enable-frei0r --enable-gnutls --enable-iconv --enable-libass
> --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype
> --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug
> --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb
> --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp
> --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora
> --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc
> --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp
> --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid
> --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib
>   libavutil      55. 76.100 / 55. 76.100
>   libavcodec     57.106.101 / 57.106.101
>   libavformat    57. 82.101 / 57. 82.101
>   libavdevice    57.  8.101 / 57.  8.101
>   libavfilter     6.105.100 /  6.105.100
>   libswscale      4.  7.103 /  4.  7.103
>   libswresample   2.  8.100 /  2.  8.100
>   libpostproc    54.  6.100 / 54.  6.100
> Guessed Channel Layout for Input Stream #0.0 : stereo
> Input #0, aiff, from 'temp_music.aif':
>   Duration: 00:01:26.68, start: 0.000000, bitrate: 1536 kb/s
>     Stream #0:0: Audio: pcm_s16be, 48000 Hz, stereo, s16, 1536 kb/s
> Guessed Channel Layout for Input Stream #1.0 : stereo
> Input #1, aiff, from 'temp_voice.aif':
>   Duration: 00:01:26.68, start: 0.000000, bitrate: 1536 kb/s
>     Stream #1:0: Audio: pcm_s16be, 48000 Hz, stereo, s16, 1536 kb/s
> Output with label 'final' does not exist in any defined filter graph, or
> was already used elsewhere.
>
> But then I receive an error:
>
> Output with label 'final' does not exist in any defined filter graph, or
> was already used elsewhere.
>
> Anybody knows why?

outputs pads names apparently can not have more than 2 chars.