I'm seeing an audio sync issue with MC 8.4x where the audio is about 1 frame late while editing.  I'm not using an external monitor -- I'm simply talking about the composer monitor window in the editing interface.  The issue is not an LCD delay issue because this would put the sync in the opposite direction (i.e. the video would be late.)

I've read about various audio or "delay compensation" capabilities in MC 8.1 and later, but I can't seem to fine these, and I'm not sure if these would apply to me anyway since, once again, I'm not outputtting to an external monitor.

Does anyone know how to solve this?  I have to slip my audio a frame early to get the sync lined up while edting, but I fear that the audio will then be a frame early when I eventually output the project to a single file.

Thanks for any help with this,

Larry

PS.  Once again, this is with Avid 8.4x.  I'm judging sync by eye, but this is not that difficult with single frame flashes that line up with the audio.  It's only a single frame off, but it's still quite visible in this situation.

Are you saying this has only started happening in 8.4 and with previous versions, the sync was fine?

There is a 'Desktop Play Delay' setting, but I thought that effected both audio and video. I seem to remember using it once (in the dim & distant past) when outputting to a DV recorder via firewire, so that the recorder output and the desktop playback were in sync. I don't know of any other delay setting specifically for audio, but if you look at the 'Audio' settings, there are play buffer setting sliders. Never had a need to change these, so I don't know what effect they have, but mine are both set to 12288.

Other than that, I would suggest ruling everything else out by looking at your OS sound settings, listening with both headphones and speakers using the rear and front jack sockets (if your workstation has these) and checking what device your sound is being handled by. Some motherboards have their own sound chips/controllers built in, which you could try in preference to your sound card (if you have one). Some graphics cards have there own sound chips built in, which sometimes takes control of your sound. I had this happen with a Quadro 4000 card when I installed the certified drivers for it.

You could also try installing version 8.5 (or even 8.6) and seeing if this cures the problem.

Bruno

Might have to do with your sound hardware as well - I don't see your platform specs posted in your signature so it's hard to know. As Bruno asked, are you saying that in 8.3.x you did not see this delay (on exactly the same hardware)?

Due to the specific projects I was editing, I can't actually be sure when it started other than to say that it definitely didn't use to happen.  I happened to be working on a project that had single frame flashes lined up with sound, and suddenely noticed that it looked off.

The sound hardware is Creative X-Fi.

It's important to note that I have some mp4's specifically designed to test sync, and the sync looks accurate when played in both Windows Media Player and Media Player classic.  This rules out a "system wide" issue causing the sync problem since the issue is unique to the Avid interface.  In other words, if the problem was in the hardware chain, it would happen in these tests as well, but it does not.

I have not done extensive testing yet with outputting/encoding projects in Avid and tracking the behavior along the entire chain -- my time is simply too limited right now.  I'm just trying to figure out if there is some sort of setting in Avid that would explain this since at this point, I'm only seeing the issue in the composer monitor in the MC interface.

Thanks again for the help,

Larry

PS.  The forum still isn't sending out emails when someone replies to my posts even though the forum has my correct email address and the "Email me replies to this post" box is checked.  This has been happening for a little while now. 

The MP4 makes me wonder if that could be the culprit. Does it play in sync if you transcode to some codec that is native to Avid (like DNxHD)?

Job ter Burg:

The MP4 makes me wonder if that could be the culprit. Does it play in sync if you transcode to some codec that is native to Avid (like DNxHD)?

I'm not clear what you mean here.  It's the mp4's that do NOT have the issue, so why would they be the culprit?

To clarify, I have pre-exisiting mp4 files that were specifically created to test sync on computers.  When I play these files in WMP or MP Classic, they play in sync -- i.e. there is no problem.  It's ONLY in the Avid MC interface that the sync issue is happening.  Outside of Avid, things are fine.

L

Sorry, I incorrectly assumed you were using exactly those MP4's as sync check sources in MC...

Job ter Burg:

Sorry, I incorrectly assumed you were using exactly those MP4's as sync check sources in MC...

Ah - I see where the confusion occurred.

No - it's just in Avid that I'm seeing this.

The "Desktop Play Delay" doesn't help, by the way, because this delays the audio.  The problem is that the audio is already a frame late, so this doesn't adjust in the right direction.

L

Just as a matter of interest, have you tried the old trick of deleting the Avid site settings? Just a stab in the dark, but sometimes this seems to fix some unexplainable problems.

I would delete yor MCstate settings, start a new project and create a new user setting. Then import your sync-testing mp4 to an Avid DNX resolution and check the sync. Does it happen in both source and record monitors?

Bruno

Haven't tried deleting settngs yet, but I have to keep moving on this project, and don't want to do anything that could slow me down at this point.  I'll have to try some other things and do some more complete testing later, but I think it would be wise to just keep pushing forward at this point.

Thanks again,

L

Hi,

did you figure out what the problem was? Or did you find a way to get it right?

I have the same problem.

Thx,

Max

Max Zilker:

Hi,

did you figure out what the problem was? Or did you find a way to get it right?

I have the same problem.

 

Thx,

Max

Unfortunately, I never did get to the bottom of this.  I found that on a similar note, my encoder shifts the audio slightly as well when importing output from Avid, which means that I had to manually shift the audio to line it up before encoding anyway.  Given this, and the fact that at least my final output is in sync, I put my investigation into this issue on pause.  I believe that I did eventually try deleting my Avid settings, but it did not help.

On a side note, I plan to eventually do some tests to see if the shift in the encoder is due to using the DNxHD codec in Avid, but all the troubleshooting takes a lot of time that I end up spending on other things.

Please let me know if you ever get anywhere with this issue.

Thanks,

Larry

Hard to believe but be aware that many well known and widespread cameras shoot the audio out of sync, pehaps it's not MC at fault.

lalittle:

It's important to note that I have some mp4's specifically designed to test sync, and the sync looks accurate when played in both Windows Media Player and Media Player classic.

Did You import into MC (no linking) the test files?