Audio requires a bit more of work: 2, 4, 6 or as many as 8 audio channels can be found. The audio format is usually PCM, 48000Hz, 16 bits. Sometimes, audio is encoded as 24 bits integer (in24). In rare occasions, audio is embedded inside dedicated DV-DIF structures of the video frame.
The way audio and video data is interleaved depends on many factors: settings, recording device, ...
Therefore, a custom Repair Kit has to be written for each case.
DVCPro HD is a family of formats. The main profiles of DVCPro HD media are:
- DVCPro HD 720p50. (not supported by Apple's DVCPro HD codec, but by some third parties)
- DVCPro HD 720p60. Resolution 1280x720, progressive
- DVCPro HD 1080i60. Resolution 1920x1080, interlaced
- DVCPro HD 1080i50. Resolution 1920x1080, interlaced
How to repair a DVCPro HD file?
The easiest way is certainly to ask our Movie Repair Service to help you recover the lost footage.
But for those who can program, here you have a few tips:
To perform a repair, it's necessary first to determine which profile is used.
If you take the 1F 07 00 pattern as reference (beginning of frame), the positions 5, 6, 7 have a value of 0x79.
Position 3 is either 3F or BF.
Position 451 can take several values.
To interpret those values, please refer to ffmpeg source code. The tables are at the end of the file dvdata.h (search for DVprofile)
Then, parsing is easy as the frame has a fixed-length:
- 720p - 240000 bytes per frame, starts on 1F 07 00 or 1F 03 00
- 1080i - 480000 bytes per frame, starts on 1F 07 00
- 1080i50 - 576000 bytes per frame, starts on 1F 07 00
Note: 1080i50, aka 'DVH5' not available as compressor, so reindexing has to be done with 'dvhp', then patched.