59.940fps to 29.97 intermediate files

rraud wrote on 3/9/2011, 12:34 PM
HELP! I'm tying to make a proxy file for laptop editing, but when I render the 59.940fps M2TS to a smaller and more efficient 29.97 AVI (or MPG) which plays great, but it drifts out of sync with the separate audio track(s). (about 5 frames out @ 10 min.s. The 40 min. original file and proxy differ in length by about 18 frames.) I've tried rendering in VP and other encoders and muxers but nothing works. What am I doing wrong?
Thanks, Rick
(aka, rraud from the SF and Vegas audio forums)

Comments

kairosmatt wrote on 3/9/2011, 6:29 PM
rraud,

How did you render out the separate audio track? Can you just render in with the AVI or MPG one time? Or does that drift out of sync too?

I'm guessing that you've checked the original (non-proxy) files and they are not out of sync after 10 minutes?

You could also try rendering out a 59.940 AVI with less resolution for the proxy (HD-SD).

kairosmatt
kairosmatt wrote on 3/9/2011, 6:30 PM
Actually, can't you just stretch the audio and leave the pitch the same?
ChristoC wrote on 3/9/2011, 6:43 PM
Help files suggest making Proxies at same frame-rate as original. I imagine that is so when Proxies are replaced for final render there can be no possibility of errors.
rraud wrote on 3/10/2011, 8:24 AM
Thanks for the response my friends

"How did you render out the separate audio track? "<>
I did not render the audio tracks.

"Can you just render in with the AVI or MPG one time? Or does that drift out of sync too?" <>
I will try that, but won't the cuts be off when I return to the source files?
Can you recommend a pre-set and/or settings for rendering the Proxy files?

"I'm guessing that you've checked the original (non-proxy) files and they are not out of sync after 10 minutes?"<>
Everything is fine with the original (non-proxy) source files.

"Actually, can't you just stretch the audio and leave the pitch the same?"<>
I've tried that, but it gets complicated. (see addendum) Wouldn't the source file (same event) also be affected when I return to and render that ?

---------------
"Help files suggest making Proxies at same frame-rate as original. I imagine that is so when Proxies are replaced for final render there can be no possibility of errors."<>
I can't find any encoders that will retain the original frame rate or have a 59.9 setting.[/i]

Addendum. It's a two-camera shoot w/ b-roll. The client gave me M2T files, the audio tracks were not embedded in the video (separate 48k WAVE files). Cam A & Cam B media are single 40 minute files. Clap-slated when the takes start/re-start. I muxed them to M2TS. No problem there.
I first made the proxies using eRightSoft's Super, which encoded quickly and made nice small efficient files. Having thought the 'Super' encoder was the problem, I encoded in Vegas, but got the same result going from 60' to 30'

Thanks again, Rick
musicvid10 wrote on 3/10/2011, 8:33 AM
Rick, by chance was the original footage shot on a Canon Mark II 5D or 7D?
Did the client then transcode them to m2ts?
Former user wrote on 3/10/2011, 8:52 AM
Do you know for sure that the audio tracks don't drift relative to the original video files? If they were given to you as a separate element, they were probably recorded on an external device and may not be locked to the video by any sync generator.

Dave T2
rraud wrote on 3/10/2011, 9:56 AM
No MV, not a Canon, two JVC GY-HD250s (HD tape) The audio was recorded to the camera's audio. They gave me M2T video files and WAVE audio files they ingested from the tapes via FW, I think they used Avid Liquid for ingesting the data. I trans-coded the M2T files to M2TS. No problems there, all video and audio files sync without issue, it's only when the video is encoded to a lower res. 29.97fps the length difference occurs. MPEG or AVI makes no difference. I'm in the process of rendering a low res 59.940fps file.

DaveT2, As I stated above, all the original video and audio files sync without issue.


Thanks
musicvid10 wrote on 3/10/2011, 10:17 AM
That rules out the Canon 30fps bug.

Can you upload a clip of your m2ts somewhere? I'm sure someone here could sort it out if we put our collective brains to work on it.
rraud wrote on 3/10/2011, 7:13 PM
I rendered a new low-res clip 59.940 and that holds sync. Seems to play OK, about 1/3 the size of the source file.
However I'll post 1 min clips of the video and audio. I assume it's not normal for a 29.9 rendered from a 59.9 to be off that much?
Thanks for your help MV, I'm new to the video editing side of Vegas. I've been using Vegas audio since V2. Full time pro-audio since...78'. Musician and part time sound mixing from ... I'd rather not to say...
musicvid10 wrote on 3/10/2011, 7:35 PM
Thanks for your help MV, I'm new to the video editing side of Vegas. I've been using Vegas audio since V2. Full time pro-audio since...78'. Musician and part time sound mixing from ... I'd rather not to say... "

And I'm also an audio edttor, with rather unremarkable video editing skills also since V2, who has more or less made the transition from still photography to video, again unremarkably. Also pro musician, producer and sound engineer since . . . (whenever, before 1970)

"I assume it's not normal for a 29.9 rendered from a 59.9 to be off that much?"

It shouldn't be off anything if the frame rates are an exact multiple, as your response suggests.

So, can you upload an original someplace? MediaFire, Dropbox are good choices.
LReavis wrote on 3/11/2011, 2:19 PM
Just to confirm - I've recently been creating Cineform 59.9 intermediates, which I then render to .MXFs for use in Handbrake @ 29.9. I have noticed no drift (but my longest project, so far, has a 40-min. duration)