View Full Version : play back not starting at cursor position

04-21-2008, 08:41 AM

I am mixing a feature doc, 90 minutes approx, and I am having a problem with playback not starting exactly from the place I put the cursor. When starting play back, the cursor "jumps back" just a little bit and Pro-Tools plays back from a location prior to where the cursor was placed. This makes it very difficult to accurately edit dialogue. I do not have any pre-roll and the midi count off is not active. My session is a 5.1 surround set up with DV movie and uses 3 dsp for about 96 voices and the highest high hardware buffer setting, which in my system appears to prevent random digital clicks and pops. I do not have auto delay comp active and I am using Waves Surround Tools RTAS (the waves manager) on my matster track. I am in the middle of the project and I have not tried the usual trash pref fixes.

PT HD 7.3 latest cs for 7.3
G5 dual 2 gig
Osx 10.4.7
2 gig ram

04-21-2008, 09:19 AM
It's called pre-roll.
Look it up, you can turn it off with a key command or from a menu.

04-21-2008, 09:33 AM
How much is it jumping back?

04-21-2008, 09:43 AM
"It's called pre-roll.
Look it up, you can turn it off with a key command or from a menu".

Nope!, it is not the pre-roll but thanks for trying to help anyway. The cursor is jumping back just a bit, may be a few letters on a word. If I wanted to edit the word "disaster" and set my coursor on the letter "t" and hit play back, Pro-Tools would start playing back from the "a" letter. Again, there is no pre-roll or post-roll or count off enabled in the system.

Rail Jon Rogut
04-21-2008, 09:51 AM
You have a Movie Track.. it's probably forcing the cursor to start on a frame boundary.


04-21-2008, 10:29 AM
Thanks Rail, that makes sense. This is the first time I encounter this problem. Do you now if there is a solution but by keeping the movie on line?. The movie file was given to me and I don't know if it was correctly conformed to start at a whole frame. I could edit the movie with Pro-Tools but I don't think that would help unless I physically move the movie to line up to a frame grid..but that would through the sync out.

Thanks again

Rail Jon Rogut
04-21-2008, 10:57 AM
I had to scour the DUC.. but here you go...

Link (http://duc.digidesign.com/showflat.php?Cat=&Board=UBB16&Number=1158545&Forum=,,,,,,,,,,,,,,,,All_Forums,,,,,,,,,,,,,,,,&Words=%2Bvideo%20%2Bframe&Searchpage=16&Limit=25&Main=1157753&Search=true&where=bodysub&Name=&daterange=1&newerval=1&newertype=y&olderval=&oldertype=&bodyprev=#Post1158545)


04-21-2008, 11:42 AM
Thanks for the link. It looks like this is going to be very bad because Digi's suggested work around requires me to move the video and change session start. I can't do that and tell my clients that "that is the suggested work around" ANT that the final output files will no longer be in sync with their video time line . The audio came form an OMF, which made a PT session that visually and sound wise "locks to picture in the Pro-Tools' environment", I just can't properly edit, or bounce to disk, unless I change the start of the session and move the video to the frame boundry?

Thanks a lot for finding the link


Rail Jon Rogut
04-21-2008, 11:52 AM
If you disable the Movie Track does it still force playback to be frame accurate? Otherwise the only way around it would be to "Save Session As", remove the Movie Track, do the edit, then Import the Movie Track.


Bob Stewart
04-21-2008, 12:30 PM
I am running LE 7.4 with the DVtoolkit, and am having the same problem... when I hit play(or the spacebar), the cursor jumps back about a frame, and plays from there.... not the best thing while trying to edit dialogue.....

I am using a movie track, so first I disabled the movie track, and then just ended up making a new session, with only 1 audio track, and nothing else... and it does the same thing...

I also have LE 7.3.1 cs5 running on a PC, and it does not do this....

On the mac side, I am using a macbook (late summer 2007), running 10.4.9, with a 003R.....

04-21-2008, 12:37 PM
Thanks, the only thing is that the documentary is "all" interviews, clip after clip, of rock and roll, heavy metal, band members and of course recorded in bars, concerts, basements, etc. You can imagine that the quality of the audio greatly varies from interview to interview. It would be impossible to tell the director that we have to edit dialogue -the entire film of all four tracks he prepared from his video- without picture (save session copy no video and do audio edits then re-import video). This is exactly what I was hired to do, edit sound to sample level if necessary to have seamless fades and transitions, but ...of course...while locked to picture so I can see when a person is on capera and when a line or word can be removed.

Thanks again, if I find a work around I'll post it

Rail Jon Rogut
04-21-2008, 12:56 PM
If you have an older version of Pro Tools (6.9 or 7.1) - use that. Create a new external boot drive, and install 6.9 or 7.1 to that and use it for this project (that's what I'd do).

I guess the change was made in 7.2


04-21-2008, 01:02 PM
Digi, can you respond?

Bob Stewart
04-21-2008, 01:11 PM
Does the same thing happen for you on a session without a movie track??

As I am running LE, we may be seeing different problems....

04-21-2008, 01:15 PM
Yes, I'll try that. I think it would be good to have the older Pro-Tools anyway (to do all the stuff the Digi screwed up after 7.2). I just bought a new firewire drive so I can free up an older firewire drive, wipe it out totally, and install the old PT. Do you know if there would be any problems with installing the entire OSX on the firewire boot drive and how would I deal with the authorization key at the back of my computer? I think my authorizations would no longer work,as I would have to re-authorized to the new boot drive but how??? if I am already authorized for the main boot drive? so I would loose all my plugins?


Rail Jon Rogut
04-21-2008, 01:22 PM
I'd use Carbon Copy Cloner to clone your boot drive to the external, then boot off the external, do a clean uninstall of Pro Tools.... then reboot off the external and install 7.1 (or whatever).

All your plugs will work if they're compatible with the version of Pro Tools you're running.


04-21-2008, 01:37 PM
Thanks, I'll try your approach!

04-21-2008, 01:52 PM
Is it possible that you have 'dynamic transport' enabled in the 'Options' menu?

I can't reproduce the symptom you're describing unless I enable D.T.

Playback should start from the exact cursor position and is not tied to frame boundaries...

Bob Stewart
04-21-2008, 02:17 PM
I realize that I am not in the correct forum, but I am having the same problem (also editing a documentary)... I will move over to the LE , or Post forum.... I do not have dynamic transport on, and the cursor and start position does jump back about a frame from the cursor position when I hit play..., I was just curious if garnoil is having the same problem with a session without video.....

back to the kid's table.....

04-21-2008, 03:01 PM
Thanks digi, I will check about the DT but I don't think so.


04-21-2008, 05:21 PM
No Digi, Dynamic Transport is NOT on, just checked the session.

04-22-2008, 01:44 AM
If you set your transport to shuttle (if it isn't already) in the preferences/operation:

does pressing 0 on your numeric pad play correctly from your cursor position? does scrubbing with 6 on your numeric pad play correctly from your cursor position?

Maybe this works?

04-22-2008, 03:44 AM
I'll try that too, thank you.

04-22-2008, 03:53 AM
No to both of these possibilities.

* does pressing 0 on your numeric pad play correctly from your cursor position?
* does scrubbing with 6 on your numeric pad play correctly from your cursor position?

As soon as I have time, I will deconstruct this session one element at the time to see what is causing this problem. Even with the video off line, and without the firewire video output active, and with a 0 quarter frame offsets cursor continues to "jump back" just a little bit.

04-22-2008, 06:37 AM
OK, DIGI, as I try to sort this "cursor jumping back" I found out a few things.

1).- Video does not appear to be the problem. Even taking the video out of the session (deleting video track) does not correct the problem.

2).- This is 100% related to the Buffer Size and possibly the Automatic Delay Compensation.

A) With Delay Comp set to "LONG" and a Hardware Buffer size at 2048 the cursor jumps back about 2 frames (the best I could measure is by eye).

B).- With Delay Comp at 4095 and Hardware Buffer at 8092 cursor jumps back about 12 frames.

C).- With Hardware Buffer size at its lowest 128 the cursor jumps back just under a frame *even here play back does not start exactly at cursor point but close* . In my case, this low hardware buffer setting appears to create a lot of digital pops and clicks so for me is not usable.

NOTE: Any of the above happens randomly, meaning the cursor jumps back "most of the time, 9 out of 10 times I would guess" but from time to time it will play correctly.

04-22-2008, 09:04 AM
Let's go back to those old standby's - trashing prefs and testing from a new admin account.

I'm really at a loss as to a possible cause and hoping it just corrupted preference files...

04-22-2008, 01:03 PM
Yes, I will do that and will let you know if it helped. I am interested in knowing if anyone else is having this problem and if this is an "unknown bug" until now that we found out. If yu suspect that your system is having a similar problem please increase your Hardware Buffer size by a lot and see if it makes the cursor jump back a lot more.

04-22-2008, 01:43 PM
We're going to look into this - at the moment I don't have any conclusive info, but will reply as soon as I do...

04-22-2008, 04:24 PM
Digi, were you able to replicate the problem? I really hope so as it would reinforce the fact that I am not insane and a fix can be found.

04-29-2008, 04:20 PM

I too have been seeing this since 7.3.x if I remember correctly. But I only see it jumping back, visually as a GUI change. Not audibly.

I printed signal generator before a sharp transient vocal take and can't hear the signal gen that sits previously at all.

The jump back looks to be related to the HW buffer like you said. Roughly 2 x the buffer setting.

Not doubting you in any way but - How can you be certain that you're hearing and not just seeing the jump?

04-29-2008, 05:07 PM
I've definitely experienced this on 7.3.1 HD. It jumps back a bit then plays audio from the cursor position when it catches up. It behaves like a very short pre-roll, but pre-roll is definitely NOT engaged. I've checked and double-checked. Sometimes it's worse than other times. Right now it's not happening, but 2 days ago it was.

What's interesting is that if I tap the Spacebar twice as fast as I can, the cursor jumps back exactly 1024 samples and stays back. I can make it inch backwards by doing this repeatedly. My buffer is set to 256. If I change my buffer to 1024, it jumps back 4096 samples. So it seems to jump back the exact buffer setting multiplied by four. Is this normal?

Maybe this is always happening but it's usually too quick to be noticeable, but on days when PT is being sluggish it's more noticeable.

04-30-2008, 08:04 AM
It acts like pre-roll with the exception you're not hearing the pre roll audio correct?

Just visually seeing the cursor jump back. At least that's what I'm seeing, and it's been this way for awhile now. Like last poster said, more noticeable when the system is going slow, IE with video.

04-30-2008, 10:32 AM
It acts like pre-roll with the exception you're not hearing the pre roll audio correct?

Right, thanks for the correction. It is different from pre-roll in that the audio plays from the actual original cursor position, not the pre-roll location. I just tested it by tabbing my cursor to the tail edge of a 2-pop and pressed play. I can see the cursor jumping back, but I cannot actually hear the 1kHz sine tone beep.

04-30-2008, 12:37 PM
In my case, and every system may behave differently, I can actually hear the sound from the point that the cursor "jumped back to". I noticed this when I was trying to cut dialoge and I just couldn't get the cursor or the sound to start at the correct place. If I was cutting the "t" from "undersTand" (of course that was not the exact word just an example), I would place the cursor at the "T" and if I played pack -before I cut- the cursor would jump back and "sometimes but not always" I could hear the whole word. Again this does not happen all the time but it happens a lot at least on this particular session.

One more thing that I noticed (well my client noticed which was very unfortunate as I had to make apologies) was that when I bounced to disk some of the bounces had a problem. What happen was that if I set a locator to locator bounce -bounce in 5.1, no video file included, file size smaller than 2 gigs- sometimes there was total silence "no audio whatsoever" at the head of the bounce. This bit of audio that was missing from some of the bounces roughly corresponded to the same amount that the cursor was "jumping back". I bounced 4 reels of a feature doc and reel 2 had this missing audio at the beginning but reel 1 and 3 were fine?

I'll be starting work on a feature film so I will keep an eye on things to see if I can detect when or how this begins to occur.

05-09-2008, 08:06 AM
I wonder if updating to the supported OS version of 10.4.9 for 7.3 and/or going to HD 7.4cs4 would help your issue? I don't think 10.4.7 is officially supported for 7.3.x

Since it's seems your issue is uniquely different than the rest of us that don't actually hear the jump nor do our bounces get cut off by that same amount.

05-09-2008, 08:33 AM
Yes, you could be right but I have only encountered this problem on one session. The only difference from the other sessions is that this one is set to BWF instead than AIF. I am starting another feature film mix on Monday and will keep a close eye on things. I'll post whatever I find. Thanks