Bitstream corruption is a category of defects that can be found in corrupt movies.
Most of the repairs consist in using raw data to re-create a movie. The raw data is actually audio and video media in perfect condition, but unplayable due to the lack of a coherent organization: the movie index.
But bitstream corruption is the opposite: The file can have a coherent index, and the movie can even be playable, but audio or video are full of defects.
This is due to bad data written inside the media. The cause is usually a defective subsystem of the camera: sensor, electronic board, memory, storage, ... Failures also tend to be more frequent in extreme conditions (temperature, humidity) or when the battery is almost discharged.
Bitstream corruption is a very serious problem, because...
- Usually you don't detect it until it's too late. The camera works, and defects may not be visible in the tiny viewfinder.
- Repair is in most cases impossible: wrong data cannot be transformed into good data.
The fact that the movies are playable is misleading: bitstream corruption is indeed a "dirty" defect, a bit like cancer. An amount of bad data as low as 1 out to 100 millions can be enough to make a movie incurable.
There are, however, cases that ended with success.
- Cases where error-hiding is possible and acceptable
- Investigative repairs
Example of success story: Corrupt Canon EOS 5D Mark II bitstream