Welcome to our community

Be a part of something great, join today!

Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Has there been any resolution to the 744T/RED synchronization issue?

Stephen Pruitt

Stephen Pruitt

Well-known member
Joined
Sep 14, 2007
Messages
3,309
Reaction score
40
Points
48
Website
www.thetreemotionpicture.com
I just got a 744T and now have read that there is an approximately two frame synch issue between the RED and the 744T. However, the last post on this issues appears to have been over a month ago.

Has there been a solution to this problem??? This is a pretty big deal to me.

Stephen
 
Yes, the SD744T. . .

Thanks.

Stephen
 
Stephen, Have you tested it yet with the most recent build? I haven't had a chance to do that test yet. But I will soon.

Clapboard is the easiest way to test.
 
Hi there, Steve. . .

I haven't got a time code clapboard. . . and I haven't even turned my 744T on yet. I could be awhile before I get around to that. . . you pros will have to answer this one.

Stephen
 
our last tests at GOTHAM SOUND indicated that we are frame accurate on Sound Devices and Metacorder BWF files - camera in jam sync

however, we are seeing 2 frame offset in SINGLE SYSTEM mode - audio coming in LINE from mixers - ????

Build 15 - anybody run SYNC tests in single system mode with build 15 using LINE from mixer??
 
Sync - Audio and Timecode to Video

Sync - Audio and Timecode to Video

I think audio is correct to maybe a fraction late within the video frame timing on Mic input using Build 15 v2.1.7 (tested with QT proxy movies FCP) See attached JPEGS.

But timecode sync is perfect with external slate (tested with Ambient ACD 301 and QuicKTime Player, RED ALERT ! and FCP

Let me know if you agree, and what you find out about line input audio sync.

(Note: In the images below the slate timecode update freezes at 22:17 so there is an apparent 1 frame offset, but its not really there)
 
How on earth could audio be that late on a line in? That's really, really strange. Surely those AD converters aren't that slow on the uptake, are they? Wow. . . this is pretty disappointing.

Stephen
 
As I recall Adam Wilt tested A/V sync on a bunch of prosumer camcorders (Sony & Panasonic cameras) and found the sync varied by about 2 frames over the group he looked at.

It's not at all hard to get that much relative delay, given these are digital devices and the video encoding latency is usually more than one frame (meaning there is a multi-frame "pipeline" taking data from imager to storage device.) The audio is normally much less delayed through the A/D, so delay must be added by using a FIFO buffer, to get it to match up. Many camera models don't have exact A/V sync, but of course, a properly designed camera should match exactly.
 
Stuart English said:
I think audio is correct to maybe a fraction late within the video frame timing on Mic input using Build 15 v2.1.7 (tested with QT proxy movies FCP) See attached JPEGS.
Click to expand...

I'm sorry Stuart but isnt the sync off by almost 2 frames in those shots?
Slate says xx:17, TC from red says xx:18, and the audio is pretty close to xx:19.
 
Timecode

Timecode

I'm sorry Stuart but isnt the sync off by almost 2 frames in those shots? Slate says xx:17, TC from red says xx:18, and the audio is pretty close to xx:19.
Click to expand...

That is a good question Anders, but the slate timecode update visually freezes at 22:17

So there is an apparent 1 frame offset, but its not really there.

Also if I jog the timeline in FCP, I hear the clap start on frame 22:18 and it continues on frames 22:19 - 22:21
 
Ok, cool.

Well bad sync is something the audio guys will fix in post, right? :whistling:
 
Too cute, Anders. . .

I'm sure what you REALLY meant to say was "who cares if the audio is synched. No one will really notice."

:-)

Stephen
 
The original DVX100 was out by two frames when in 24P mode. That's why they introduced the DVX100 offset tool in FCP to get things back in sync.

I haven't had a chance to do the test yet, but as soon as I do, I'll let you guys know what I come up with. I'm also going to do some other audio tests.
 
Been busy, but it's on my agenda when I get back from NAB.
 
I should have my camera soon (next round) and intent to do some tests to nail this down
 
You must log in or register to reply here.
Back
Top