ALL: Rewrapping AVCHD?

[Laguna Hiker]

Has anyone found a reliable method for rewrapping the H.264 content of an AVCHD file hierarchy in either MP4 or MOV files on Windows 7? I expect to hear some "No, don't do it!" advice, so let me explain my purpose. I have recorded quite a bit of oral history for a documentary I'm finishing up. I am going to archive my raw footage with a historical society for use by future researchers. The footage is in AVCHD from my AC130, and I suspect that twentry years from now, that may be a difficult format to read. So, I'd like to rewrap my footage in self-contained files, such as an H.264 MP4 or MOV, for archiving.

I have tried using FFMBC from the command line, and from several of the GUIs that are available for it. Picture rewraps fine, but audio is either transferred at the wrong frame rate or not at all. I want to rewrap, rather than transcode, to avoid generational loss in the transfer.

Are there any Windows apps out there than can rewrap AVCHD reliably? Has anyone managed to get it to work with ffmbc? Thanks for your help.

[David Jimerson]

So, I'd like to rewrap my footage in self-contained files, such as an H.264 MP4

Anything that can read these can read AVCHD. They're variations of the same thing. As for MOV, it's a wrapper; the codec will still be the codec, so if something can't read the codec, the MOV wrapper won't help you.

I'm also not aware of any older codec -- even those going back 20 years -- which can't be used today, unless it's some proprietary thing kiboshed by its creator. AVCHD isn't.

[Laguna Hiker]

I appreciate your advice, and I understand what you are saying. Yes, AVCHD, MP4, and MOV all wrap the same codec--H.264. That's why I want to rewrap--no generational loss.

I see things a bit differently as to whether a MOV wrapper will help me. An AVCHD wrapper is a rather brittle file structure, and there is a very good chance that the file hierarchy could be disrupted during the archival life of the footage. Anything that can go wrong probably will. So, I want to archive in the most bulletproof format I can find. Using a MOV reduces the odds that the footage would be rendered useless because an ancillary file was moved or accidentally deleted by a careless researcher.

As to whether AVCHD will be readable twenty years from now, I'm afraid that I'm not willing to bet on that. The pace of change is accellerating quickly, and while I hope that legacy codecs and formats will be readable two decades from now, I have seen too much computer media (including media from the NASA lunar missions) that has been effectively lost, because it can't be read. And all that leads me to archive in the simplest, most durable H.264 wrapper that I can find.

And so I return to my original question: Has anyone had any success rewrapping (not transcoding) AVCHD in a MOV or an MP4 wrapper? Thanks for your help.

[demoboy]

You already answered your own question. You're thinking too much of responsibility. If it's for the sake of future use then whoever's archiving, meaning the institution, should ideally re-archive digital files every year or after for whichever new based memory system they have.

An NLE is technically ''unwrapping'' the file so that you can see the original codec in the playback window. That's from the NLE's engine. I master archive all my stuff to AVI uncompressed because my NLE is extracting the originally recorded codec to a master format via non-compression, hence uncompressed. Of course the final rendered file is HUGE, but a 40-60GB master file for me is nothing when nowadays 2TB externals are already the norm. In the future I can then go ahead and transcode to whatever newly introduced compressed formats in the industry from my original master AVI uncompressed files. I don't need to worry about the originally recorded codecs or wrappers ''breaking'' apart or not being able to play. As far as I know there are many uncompressed wrapper formats including MOV. Lastly, I'm more than sure that even 20 years from now every NLE will have every known codec or else what's the point of our industry doing good at what it does. Analog or video tape are of course different worries...

[Sol M.]

This is what I used to rewrap the GH2's MTS files to MP4 using FFMBC:

ffmbc -i "file.m2ts" -vcodec copy -acodec aac -ab 256k -strict experimental "file.mp4"

Note that the AC-3 audio codec cannot simply be copied and must be transcoded to AAC because the MP4 container doesn't support AC-3. If you do a direct copy of the AC-3 audio to the MP4 container, then you'll have a file that works in some programs, but not in others. Transcoding the audio is unfortunate, but necessary. At least the video does not need to be modified in any way.

[MadHMC150]

Have you looked at clipwrap? http://www.divergentmedia.com/clipwrap

[Laguna Hiker]

I'm on the Windows side, so no luck there. I'm actually looking for a Windows equivalent of ClipWrap, which I'm told works very well.

[Laguna Hiker]

I've been testing AW Pro Client today, and it seems to do a good job with the rewrap. It's a pretty good Windows front end for FFMBC So, I'd say my problem is solved.

[Laguna Hiker]

I see it a bit differently. I have found archivists to be technically less sophisticated than video editors and producers. An asset gets tagged, bagged, and forgotten. If I choose my archival format wisely, a researcher one hundred years from now will be able to read my footage. That's important to me as a producer of historical documentaries, because most of the photographs and physical assets I work with are at least that old. I can take one-hundred-year-old nitrate film and, if it has somehow survived this long, get a digital transfer from it with quality equal to the original. However, much of NASA's video from the Apollo era has been lost, because it was recorded in a format that is now lost. If it wasn't reduced to 35 MM film in the 60s, it can't be recovered. I'm willing to bet on MP4 being readable in a hundred years--I'm not willing to bet on MTS.

[ELN614]

... I can take one-hundred-year-old nitrate film and, if it has somehow survived this long, get a digital transfer from it with quality equal to the original. However, much of NASA's video from the Apollo era has been lost, because it was recorded in a format that is now lost. If it wasn't reduced to 35 MM film in the 60s, it can't be recovered.

You are slightly confused between format and medium. Digital hard drive is a medium. .mov is a format. The format may not be used as an active primary type 20 years from now but software programs should still be able to read the file and transcode to another format. Your example of NASA issue is the medium NASA used to record the footage is no longer supported. (granted I know nothing of what medium they used and just assume Laguana knows more than I but it doesn't change the fact that he proved that the medium is more important than format. that being 100 year old nitrate film can still be transferred.) a great example for medium unsupported in years to come. magnetic tape storage, 5.25" floppy, or iomega zip drive (100mb cartridge). or IDE connector in 20 years all hard drives will be solid state and the connector won't be SATA. I assure you, assuming the file is intact and can be read through a SATA to a computer 20 years from now... it can be recopied to a new hard drive -- read by some program -- and re-saved to the latest and greatest compression file.
last time i checked all computers (apple and windows) can read an MPEG1 file type and MPEG1 is over 25 years old --- a file type during the beginning of computers as we know it today. heck ASCII files are still readable even if they were made before the Apollo missions started by NASA. (assuming the medium is still working or the file was transferred over time... all PCs can read the file. and "rewrap" the file to a doc or pdf)