Wrong size data on segments

[spite]

I'm using Whammy.js on a library to capture canvas https://github.com/spite/ccapture.js/ and most of the times the videos are created correctly.

However, some big videos (long videos, or videos of 1920x1080, or videos at 60FPS), don't work correctly and pieces of 30 seconds of the video are missing/can't be played. As an example, a capture of 4:07 at 1920x1080@60FPS will have all segments correctly placed, except the 3:30 to 4:00, during which there's no image. And 4:00 to 4:07 will play correctly.

I've been using HexFiend and EBML Viewer and found that some of the lengths specified in the segments are quite wrong:

If I manually fix the values for that segment other blocks inside the file will fail, so it's not immediate to see what's really going on.

Fixing this would be perfect, since Whammy.js is an amazing library for capturing on the browser, but it's a bummer if after a few hours of rendering high quality video, the resulting file doesn't play completely.

Thanks in advance!