HDSLR Audio Out of Sych in FCP Viewer

[Jerry Hofmann]

Try transcoding it to ProRes instead.

Jerry

[John Pale]

Encoding from one non I-Frame codec to another is a really bad idea. Just asking for trouble.

If you don’t have the space for Pro Res get a bigger drive or use ProRes LT.

[Ron Dawson]

I transcoded the selected clips to ProRes and that solved the problem. I’ve never had an issue like this before in the past 14 months I’ve been shooting with DSLRs (well, actually, only one other time).

I know ProRes is a higher quality codec, but 90% of my projects end up on the web at 640×360 and I do a lot of post work with Magic Bullet. Just doesn’t seem to make financial sense to triple or quadruple my hard drive investment to start using a codec that is 3-6x the size what I’m currently doing (even ProResLT). It’s a numbers game. For the occasional project that goes to broadcast, or requires heavy green screen, or will be shown at true HD size, I could see doing those in ProRes. But ALL of my projects? Just don’t know.

But perhaps there are other considerations I’m missing. I’d love to hear people’s thoughts.

[Jerry Hofmann]

H..264 is a delivery format. It’s what you can acquire it with DSLR’s. When Canon announced the first DSLR that shot HD video, they said it was designed for news photographers to be able to put the videos immediately on the web, have a video/still camera in one unit etc… not edit the stuff… Newspapers are in big trouble because of the Web as we all know, and their only defense to the Web is to join the movement… So Canon saw a ready market for the new DSLR’s… They didn’t see the video world coming at it.

Because not every frame is actually recorded int it’s entirety in an H.264 stream, it’s inefficient to edit it because the computer has to look through as many as 15 frames just to show you one, or render an effect frame by frame, or even put this video out to a tape. There are only 1 in 15 frames in an H.264 file that actually contain every bit of info about every pixel within the frame. (that’s why it’s a smaller file).

ProRes is an all i-frame format. Meaning the value of every pixel of every frame is actually in the recording. If you’re time is worth anything to you, you’ll find it renders and re-compresses a lot faster than any GOP structured media. Seems these days a lot of video is going to the web, and all those formats are GOP structured. When going from GOP source, to GOP delivery, the amount of number crunching the computer has to do is immense, and there are rounding errors in the algorithms involved no doubt. Very likely the reason that you had problems with it.

Further, ProRes is 10 bit video where what you shot is only 8 bit. So anything you add to a prores sequence will be 10 bits. (there’s 4 times as many colors possible in 10 bit over 8 bit.), and the color space is 4:2:2 or better, rather than 4:2:0 which is what you’ve shot. so any graphics, stills, animations will be of higher quality in the end.

THATs why avoiding GOP structured media is more efficient to do.

Jerry

Apple Certified Trainer, Producer, Writer, Director Editor, Gun for Hire and other things. I ski. My Blog: https://blogs.creativecow.net/Jerry-Hofmann

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8-Core 3.0 Intel Mac Pro, Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D, AJA Io HD, 17″ MBP, Matrox MXO2 with MAX Cinema Displays

[Ron Dawson]

Wow. Thanks for the thorough explanation Jerry. For this immediate project I’ll use DVDProHD. Once I can upgrade to FCP7, I’ll use one of the lighter forms of ProRes.

Thanks again.
—

Ron Dawson
Executive Producer/President
Dare Dreamer Media

Creating films that inspire and encourage the human spirit.

*** Dream Out Loud ***

[Ron Dawson]

I’ve now done three encoding tests for the same number of h.264 clips. 49 min of footage. 2 of the tests were encoded to xdcam, but taken from source files on different drives (one drobo and one seagate external), and one of the tests was a prores422 encode from the seagate. All the clips were transcoded with MPEG Streamclip 1.9.2 on OS 10.6.2 to one long 49 min clip. ALL THREE experience the same problem. The audio drift within itself. I’m using FCP 606.

I thought (prayed/hoped) encoding to ProRes would solve the problem and it didn’t. I’m going to try encoding the clips on the MBP to XDCAM to see if it’s an iMac issue.

I can’t believe no one can figure this out. If there are any Apple people on this thread, I could really use a miracle here.

I bought the FCP upgrade (which I’m loathe to do in the middle of a bunch of big projects, but this audio drift issue will be problematic for me on these projects if they persist). I hope that’ll solve the problem.

Ron Dawson
Executive Producer/President
Dare Dreamer Media

Creating films that inspire and encourage the human spirit.

*** Dream Out Loud ***