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mipops / dvrescue

Archivist-made software that supports data migration from DV tapes into digital files suitable for long-term preservation. Snapshot daily builds are at https://mediaarea.net/download/snapshots/binary/dvrescue/.
BSD 3-Clause "New" or "Revised" License
83 stars 19 forks source link

Is HDV within the scope of the project? #53

Open kieranjol opened 4 years ago

kieranjol commented 4 years ago

Just checking, I wasn't clear from the readme if HDV is in the roadmap.

dericed commented 4 years ago

do you have samples of hdv captured from tape?

digitensions commented 4 years ago

I have some from my JVC camera, personal collection if needed.

kieranjol commented 4 years ago

Joanna's might be easier to share - i have some samples alright - FCP 7 captures, but I'd have to get clearance.

digitensions commented 4 years ago

Same, FCP7 firewire captures of progressive HDV. Happy to drop some over, I have clearance for it.

kieranjol commented 4 years ago

I was given permission to share some of these but they can't be made publicly available.

JeromeMartinez commented 4 years ago

"this" HDV is https://en.wikipedia.org/wiki/HDV#Specifications and actually it has no link (not a single bit is same) with DV despite the name.

Analysis is completely different. We could reuse the same ideas and the same user interface, but we need to implement all the MPEG Video logic instead of DV logic. There is already a lot in MediaInfo library from another project (e.g. we can check if headers or macroblocks are coherent), but there is still some work for having a good MPEG Video related report.

kieranjol commented 4 years ago

Imagine how bananas it is when you have both hdv and DV content on the same tape. We encountered this a while back.

JeromeMartinez commented 4 years ago

@kieranjol I wonder how it is stored on the tape... the file you provided is a "classic" MPEG-2 Video stream in MOV, with Final Cut metadata. As far as I know MPEG-2 Video could not be as is on a tape (no small fixed packetization), Wikipedia says that is uses to be MPEG-TS (more logical) so the curating would be on MPEG-TS.

Anyway, far from this project (currently) focused on DV packetization.

kieranjol commented 4 years ago

Good point. The file I provided was from a vendor using FCP 7. Based on tests, you could only really get FCP to capture via firewire with one specific setting, which is what was used. Some sort of HDV preset. Sounds like reencoding could be happening?

JeromeMartinez commented 4 years ago

Sounds like reencoding could be happening?

No way to know if there was a reencoding. Probably a transwrapping (from MPEG-TS to MOV?).

based on tests, you could only really get FCP to capture via firewire with one specific setting, which is what was used.

Here it seems that FCP does the "rescue" of the file, but no idea what it would do in case of corrupted content, you have to rely on FDCP. Without having the raw content from the tape, I doubt that a "rescue" software would be useful (in addition to the count of HDV files vs DV files, which puts a limit to the development acceptable cost).

kieranjol commented 4 years ago

Hi - I just shared a DVHSCap with Jerome and Dave there - this should be ore of a stream grab I hope. It's Mpeg-TS.

It's probably still out of scope but thought I'd share a better example of the format.

JeromeMartinez commented 4 years ago

@kieranjol right still out of scope because it is also MPEG-2 Video instead of DV... I would love to work on a MPEG-2 repair tool, but current sponsoring is not for that...

dericed commented 4 years ago

there are some possible side effects of the project that could help HDV but the grant is written for DV.