Adding checks in
MediaConch & MediaInfo
A use case
Jérôme Martinez, MediaArea
No Time to Wait 8, September 2024
What was already there?
Initial funding was a complete checker of MKV/FFV1/PCM
Further funding was on:
- crosschecks (container vs raw stream)
- complete checker of some new formats (USAC/xHE-AAC, ADM)
- More supported formats (DVD in ISO files, ...)
Finding the right funding
A complete checker for a format is very expensive
We focused on funding the checks of the most classic errors (and easy to implement) on most common formats in the repository
Which checks in priority?
Catching a bad file transfer
- Is a file complete?
- Is a file coherent?
- Are all the frames coherent?
An example
$ ffmpeg -i Example.wav -c copy Result.wav
[...]
video:0kB audio:256kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.029755%
$ ls -l
21757952 Example.wav
262222 Result.wav
What happened?
The file is valid with 256 KiB of content from FFmpeg point of view
FFmpeg relied on a buggy WAV header
99% of content is lost during transcoding, without warning
You are warned by MediaInfo
Conformance errors : 2
WAVE : Yes
ýÿÿÿ : Yes
General compliance : Element size 4294901752 is more than maximal permitted size 1184 (offset 0x40034)
ùÿ : Yes
General compliance : File size 21757952 is less than expected size 4296672497 (offset 0x1B04F6)
Current issues
Output is based on specs, difficult to interpret
No difference between big issues and small issues:
- null padding at the end
- buggy last frame only
Next steps
Analysis and categorization of the results
More tips about the impact of the issue
More information about the impact of the issue
Stay in touch
MediaArea: https://mediaarea.net, @MediaArea_net
MediaConch: https://mediaarea.net/MediaConch, @MediaConch
Jérôme Martinez: jerome@mediaarea.net
Sponsoring program: https://mediaarea.net/SupportUs
Slides: https://mediaarea.net/Events
License: CC BY