image 25fr + sound 24fr = unsolvable problem? at DVinfo.net

Nikos Vavouris · May 25th, 2005, 02:54 PM

ok, here's the story. a movie shot on dvcpro50. the sound kept on dat. it seems that the sound guy has captured sound on 24fr (i get an indication 24fr on my dat machine when i play back the material). i loaded a long scene (about 3 mins) on avid, then synchronized audio+video. everything seems to be ok. i mean, that even at the end of the scene, the synchronization seems to be frame accurate.

according to the way i see it, this is not possible, since sound captured on 24fr cannot be synchronized with video kept on 25fr. as the clip would progress sound come earlier than the image.

can it be that avid captures the 24fr sound on 25fr, since this is the setting on the project i'm working on?

to put it in another way: who's the idiot? me or the sound guy? :-)

any help would be very appreciated...

Glenn Chan · May 25th, 2005, 04:29 PM

Sound is recorded as samples per second (typically 48k samples or 44.1k samples per second), and not as frames per second. Generally when you import sound into an editing program, it'll stay 48k samples/second or 44.1k samples/second. It'll stay in sync.

The timecode however uses different formats... and that is where you may run into problems.

I think this is right. But I may be confused here.

Matt Ockenfels · May 26th, 2005, 01:52 PM

3 minutes of video and 3 minutes of sound should sync up, no problem.

However, if you are resolving to FILM, the audio (25fps) would be referenced sproket holes (24fps) and you would see some slip.

That being said, I'm curious ... when you edit on a video frame, does the audio glitch at all? Though technically "in sync" I wonder if the different frame rates cause any anomalies?

-Matt

May 25th, 2005, 02:54 PM	#1
Nikos Vavouris Tourist Join Date: May 2005 Posts: 2	image 25fr + sound 24fr = unsolvable problem? ok, here's the story. a movie shot on dvcpro50. the sound kept on dat. it seems that the sound guy has captured sound on 24fr (i get an indication 24fr on my dat machine when i play back the material). i loaded a long scene (about 3 mins) on avid, then synchronized audio+video. everything seems to be ok. i mean, that even at the end of the scene, the synchronization seems to be frame accurate. according to the way i see it, this is not possible, since sound captured on 24fr cannot be synchronized with video kept on 25fr. as the clip would progress sound come earlier than the image. can it be that avid captures the 24fr sound on 25fr, since this is the setting on the project i'm working on? to put it in another way: who's the idiot? me or the sound guy? :-) any help would be very appreciated...

May 26th, 2005, 01:52 PM	#3
Matt Ockenfels Regular Crew Join Date: Jan 2002 Location: Issaquah, WA Posts: 62	3 minutes of video and 3 minutes of sound should sync up, no problem. However, if you are resolving to FILM, the audio (25fps) would be referenced sproket holes (24fps) and you would see some slip. That being said, I'm curious ... when you edit on a video frame, does the audio glitch at all? Though technically "in sync" I wonder if the different frame rates cause any anomalies? -Matt __________________ Matt Ockenfels a pixel a day keeps boredom at bay

May 25th, 2005, 04:29 PM	#2
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	Sound is recorded as samples per second (typically 48k samples or 44.1k samples per second), and not as frames per second. Generally when you import sound into an editing program, it'll stay 48k samples/second or 44.1k samples/second. It'll stay in sync. The timecode however uses different formats... and that is where you may run into problems. I think this is right. But I may be confused here.