[FFmpeg-trac] #5804(avfilter:new): pan audio filter parser fails to correctly parse LFE2 channel identifier

[FFmpeg]

#5804: pan audio filter parser fails to correctly parse LFE2 channel identifier
----------------------------------+--------------------------------------
             Reporter:  codyopel  |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avfilter  |                  Version:  git-master
             Keywords:  pan       |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
----------------------------------+--------------------------------------
 The pan filter only expects alphabetical characters for channel
 identifiers so parsing LFE2 fails.

 https://github.com/FFmpeg/FFmpeg/blob/eae2d89bf715bc3edff478174b43e1f388e768bf/libavfilter/af_pan.c#L73

 ffmpeg -i test1.mp4 -filter:a 'pan=stereo|FL<FL<LFE2+FL|FR<LFE2+FR'
 ~/tmp/test.mkv
 ffmpeg version 3.1.3 Copyright (c) 2000-2016 the FFmpeg developers
   built with gcc 6.2.0 (GCC)
   configuration: --disable-static
 --prefix=/nix/store/lg96h2rflg1yagkhyaw52031dkh3akl2-ffmpeg-3.1.3
 --enable-gpl --enable-version3 --disable-nonfree --disable-thumb --enable-
 shared --disable-static --enable-pic --disable-small --enable-runtime-
 cpudetect --enable-gray --enable-swscale-alpha --disable-incompatible-
 libav-abi --enable-hardcoded-tables --enable-safe-bitstream-reader
 --disable-memalign-hack --enable-pthreads --disable-w32threads --disable-
 os2threads --enable-network --enable-pixelutils --enable-ffmpeg --enable-
 ffplay --enable-ffprobe --enable-ffserver --enable-avcodec --enable-
 avdevice --enable-avfilter --enable-avformat --enable-avresample --enable-
 avutil --enable-postproc --enable-swresample --enable-swscale --enable-doc
 --disable-htmlpages --enable-manpages --disable-podpages --disable-
 txtpages --disable-audiotoolbox --disable-cuda --disable-cuvid --disable-
 d3d11va --disable-dxva2 --disable-libmfx --disable-libnpp --disable-mmal
 --disable-nvenc --enable-vaapi --disable-vda --enable-vdpau --disable-
 videotoolbox --enable-xvmc --disable-avisynth --enable-bzlib --disable-
 chromaprint --disable-crystalhd --disable-frei0r --enable-gcrypt
 --disable-gmp --enable-gnutls --enable-iconv --disable-jni --disable-
 ladspa --enable-libass --enable-libbluray --disable-libbs2b --disable-
 libcaca --disable-libcelt --disable-libcdio --disable-libdc1394 --disable-
 libebur128 --disable-libfaac --disable-libfdk-aac --enable-libfontconfig
 --disable-libflite --enable-libfreetype --disable-libfribidi --disable-
 libgme --disable-libgsm --disable-libiec61883 --disable-libilbc --disable-
 libkvazaar --disable-libmodplug --enable-libmp3lame --disable-libnut
 --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-
 libopencv --disable-libopenh264 --disable-libopenjpeg --enable-libopus
 --enable-libpulse --disable-librubberband --disable-librtmp --disable-
 libschroedinger --disable-libshine --disable-libsmbclient --disable-
 libsnappy --enable-libsoxr --enable-libspeex --disable-libssh --disable-
 libtesseract --enable-libtheora --disable-libtwolame --enable-libv4l2
 --disable-libvidstab --disable-libvo-amrwbenc --enable-libvorbis --enable-
 libvpx --disable-libwavpack --disable-libwebp --enable-libx264 --enable-
 libx265 --disable-libxavs --enable-libxcb-shm --enable-libxcb-xfixes
 --enable-libxcb-shape --disable-libxvid --disable-libzimg --disable-libzmq
 --disable-libzvbi --enable-lzma --disable-decklink --disable-mediacodec
 --disable-netcdf --disable-openal --disable-opencl --enable-opengl
 --disable-openssl --disable-schannel --enable-sdl --disable-
 securetransport --disable-x11grab --enable-zlib --disable-debug --enable-
 optimizations --disable-extra-warnings --disable-stripping
   libavutil      55. 28.100 / 55. 28.100
   libavcodec     57. 48.101 / 57. 48.101
   libavformat    57. 41.100 / 57. 41.100
   libavdevice    57.  0.101 / 57.  0.101
   libavfilter     6. 47.100 /  6. 47.100
   libavresample   3.  0.  0 /  3.  0.  0
   libswscale      4.  1.100 /  4.  1.100
   libswresample   2.  1.100 /  2.  1.100
   libpostproc    54.  0.100 / 54.  0.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test1.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf56.40.101
   Duration: 00:01:00.10, start: 0.000000, bitrate: 5916 kb/s
     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv,
 bt709), 1920x1080, 5907 kb/s, 23.98 fps, 23.98 tbr, 16k tbn, 180k tbc
 (default)
     Metadata:
       handler_name    : VideoHandler
     Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz,
 stereo, fltp, 2 kb/s (default)
     Metadata:
       handler_name    : SoundHandler
 [Parsed_pan_0 @ 0x190f820] Syntax error near "2+FL"
 [AVFilterGraph @ 0x190e660] Error initializing filter 'pan' with args
 'stereo|FL<LFE2+FL|FR<LFE2+FR'
 Error opening filters!

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5804>
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