Improved processing of some mp4 and webm files

A small number of .webm recordings contain only 1 video frame and many audio frames. As a result, these .webm files are very small in size and, after processing, have no video frames during playback and no snapshot. After today’s update, such .webm files will be remuxed and will now generate a snapshot, as well as have 1 video frame present on the video playback.

A smaller number of .mp4 recordings come in with their audio and video data not muxed correctly. These recordings do not play correctly in both their raw and converted forms. After processing, these recordings have no snapshot and report a very long duration. We’re now detecting such recordings and remuxing them before processing them further. The final converted .mp4 file will now play correctly and there will be a snapshot for such recordings. The initial raw .mp4 file remains untouched.

We’re working on the client side to see if these issues can be fixed higher up where they originate (browser bugs?).

In June, 25 recordings exhibited the symptoms above.