Damaged DV and error concealment

[2Bdecided]

I've searched, but not found anything, so...

I have a few DV tapes that were recorded while the camera tape transport was malfunctioning slightly. They're all recorded in LP mode, which didn't help.

When played back, either via the camcorder's analogue TV outputs, or copied onto the PC via Firewire, sections of the video picture (typically down the right hand side) are often replaced with the same section from the previous frame or so. On still pictures, this is almost invisible, but on pans, or with people walking across the screen, the effect is horrible disjointed blocks.

What I'm seeing looks like the in-camera error concealment kicking in, and it's not great!

So, any advice? For other tapes with small momentary problems, I've either managed to clean the heads or just play the tape again, and get a good capture. However, these specific tapes have errors throughout.

I was wondering if there was any way of "knowing" which areas had been reconstructed by error concealment - either by getting the camera to output these as 100% black, or from some tags or data in the AVI files I'm getting now.

So, is there a way for the PC to know which parts of the DV stream are damaged? (Either if they have, like now, been badly patched by the camera already, or by getting the camera to flag them instead of patching them)?

Cheers,
David.

[JohnnyMalaria]

So, is there a way for the PC to know which parts of the DV stream are damaged? (Either if they have, like now, been badly patched by the camera already, or by getting the camera to flag them instead of patching them)?

The camera doesn't patch them, the decoder does.

The DV signal contains flags to tell the decoder if data are missing and, if so, what to do to try to conceal the fact.

Each macro block of the video (for PAL, this is a 16 x 16 pixel block, for NTSC it is 32 x 8), the flags can specify that an erroneous macro block should be:

a) Replaced with a compressed macro block of the same compressed macro block number in the immediate previous frame.

b) Replaced with a compressed macro block of the same compressed macro block number in the next immediate frame.

c) This compressed macro block is concealed, but the concealment method is not specified.

d) The continuity of data processing sequence with other compressed macro block whose s0 = 0 and s3 = 0 in the same video segment is guaranteed.

e) The continuity of the data processing sequence with another compressed macro block is not guaranteed.

[2Bdecided]

Thanks John, that's really useful, and will probably make the job much easier than anticipated.

Is there a way of accessing these flags with any of the PC DV decoders and/or parsing them into AVI synth?

Cheers,
David.

[JohnnyMalaria]

I could readily add this capability to the Enosoft DV Processor that is under development.

There are a number of possibilities, including perhaps identifying macroblocks with error concealment - replace them with, say, a lurid pink (or some other distinguishing feature).

This would be done either during capture from the camcorder (it would be realtime, so the AVI file you end up with would have the errors identified) or could be done on pre-existing AVI files (as long as they are DV).

Please let me know if you are interested (note, you'll need XP with a processor that supports SSE2).

[2Bdecided]

It would be interesting if I could pull the output into AVIsynth and do something useful with it.

However, as with everything in life, it depends on the cost! I can't get your enosoft link to work.

Cheers,
David.

[Fizick]

http://forum.doom9.org/showthread.php?t=106238

[JohnnyMalaria]

I can't get your enosoft link to work.

We had a major power loss in this part of the world on Wednesday due to high winds. About 30,000 people were without power for most of the day and night.

EDIT - looks like the link in Fizick's reply would help you tremendously (and straightaway, too)!

[2Bdecided]

Great link but no binary! It seems like just what I'm looking for.

Rapid share is blocked from here anyway. Do you have any other link to a binary please Fizick? Did anyone host it? Thanks!

Cheers,
David.

[Fizick]

I added new link