Decode-Validate is among the most advanced repair techniques.
The main difficulty when reindexing a damaged movie is to correctly identify the frames. The beginning of video frames is usually easy to find, due to the presence of a certain data pattern. But the end of the frame can be extremely difficult to find, when the next data block is an audio block whose data seems indistinguishable from video.
In such cases, Decode-Validate can be the only possible repair technique.
It consists in using a video decoder to determine where the frame ends. Indeed, for each frame the decoder uses a certain quantity of information. It knows what information has been used, and what information hasn't, so the decoder can tell where the frame ends.
Decode-Validate is used mainly for repairs involving MPEG4 Video or AAC audio.
Main challenges
Writing a Decode-Validate program
It's a very hard task. Not because the program is very long (a few hundreds of line of code can do it), but because it requires deep understanding of a few technologies that are hard to learn:
If you have a few hundreds of hours to waste, you can try. Otherwise, it's certainly better to ask our Movie Repair Service to do it for you.