TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType' in TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

[Muelli]

I tried to convert a file from webm to h264. The file does not have sound.

Traceback (most recent call last):
  File "transmageddon.py", line 1013, in on_transcodebutton_clicked
    self._start_transcoding()
  File "transmageddon.py", line 845, in _start_transcoding
    self.audiodata, self.videodata)
  File "/usr/share/transmageddon/transcoder_engine.py", line 82, in __init__
    self.provide_presets()
  File "/usr/share/transmageddon/transcoder_engine.py", line 221, in provide_presets
    if int(self.audiodata[0]['audiochannels']) < int(chanmax):
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

Funnily enough, mplayer does not play the file. See https://bugs.launchpad.net/ubuntu/+source/mplayer2/+bug/1513080

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: transmageddon 1.5-3
ProcVersionSignature: Ubuntu 3.19.0-31.36-generic 3.19.8-ckt7
Uname: Linux 3.19.0-31-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.7
Architecture: amd64
CurrentDesktop: GNOME
Date: Wed Nov 4 14:53:51 2015
PackageArchitecture: all
SourcePackage: transmageddon
UpgradeStatus: No upgrade log present (probably fresh install)