Support video files with no language data

[Arthaey]

I have an .avi video file that has no language data. substudy list tracks myfile.avi outputs the following error: MissingFieldError("tags")

For what it's worth, here's the output from ffmpeg -i myfile.avi:

ffmpeg version 2.4.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Oct  8 2014 19:37:09 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --arch=x86_64 --enable-runtime-cpudetect
  libavutil      54.  7.100 / 54.  7.100
  libavcodec     56.  1.100 / 56.  1.100
  libavformat    56.  4.101 / 56.  4.101
  libavdevice    56.  0.100 / 56.  0.100
  libavfilter     5.  1.100 /  5.  1.100
  libswscale      3.  0.100 /  3.  0.100
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  0.100 / 53.  0.100
[mpeg4 @ 0x7f84b280fe00] Failed to parse extradata
Input #0, avi, from '/Users/arthaey/Downloads/myfile.avi':
  Metadata:
    encoder         : VirtualDubMod 1.5.10.2 (build 2540/release)
    title           : MyFile
  Duration: 01:11:42.00, start: 0.000000, bitrate: 1651 kb/s
    Stream #0:0: Video: mpeg4 (Advanced Simple Profile) (XVID / 0x44495658), yuv420p, 704x400 [SAR 1:1 DAR 44:25], 1317 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc
    Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, stereo, fltp, 192 kb/s
    Metadata:
      title           : MyFile
    Stream #0:2: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, s16p, 128 kb/s
    Metadata:
      title           : MyFile

[emk]

Thank you! Closed in f22018e.