FFMpeg transcoding is broken in Firefox

[nathanathan]

When attempting to do FFMpeg transcoding in Windows Firefox I've encountered a few bugs, in both nightly and the stable version.

There is a Heisenburg effect where RecordRTC.getBlob() will sometimes return undefined, but if there is a break point before it, it seems to never return undefined.

When FFMpeg runs I will occasionally get this error:

asm.js link error: As a temporary limitation, modules cannot be linked more than once. This limitation should be removed in a future release. To work around this, compile a second module (e.g., using the Function constructor).

and when FFMpeg completes it will always sends a "done" event where result.data has a size of 0.