Calculating how much data (avi) is missing

[marnix88]

Hi, Gspot tells you if an avi video is truncated and how much of the video is missing.

I know I can check to see if the AVI has an index (idx1) to find out if it's truncated, but how can I calculate how much of the file is missing?

Thank you.

[marnix88]

I read that the original file size is somewhere in the riff header (4 bytes) and that you can compare the real size of the AVI with the size in the riff header, but where is the real file size stored in the riff header?

[unmei]

right after the RIFF identifer, that is

00 - 03 'RIFF'
04 - 07 size (that is, total RIFF file size minus the 8 byte used up to here)
08 - 11 FormatID (ie 'AVI ')
(other RIFF (sub-)chunks)


Note that this will not work for OpenDML Avi's larger than what this 4-byte int can hold. It's little endian and i think "signed" or at least better not use the MSB.

[marnix88]

Thank you, unmei.