Video playback with Audio. Sync error?

[NevBull]

try this - rerender the clip to 832 x 1024 and let me know if that helps


You may find that as the horizontal pixel count is not a multiple of 16 - the content may run like a dog.

Nev.

[SourceChild]

try this - rerender the clip to 832 x 1024 and let me know if that helps

Nev.

ah, good eye Nev.

[pip]

Thanks Nev, that stopped the clip from dropping frames every second or so as before. Runs much more smoothly.

The only thing it still does, which i don't understand the stats window, there is still a frame or so dropped when this pink bar (in image below) jumps from top image to bottom image. The bar then slowly decreases and then jumps back up every 10-15sec. On doing so the video glitches.

[ajmaudio]

do you have any video inputs enabled? I have seen similar issues when several inputs where enabled... interestingly it seems to be a Snow Leopard thing...

[SvenCRen]

Okay, I have a few thoughts on this subject. I have had these problems on many occasions and have yet to find a solid solution for it.

Here is what I understand:

1. Running the video with an audio play mode when they are merged together in the same file can cause playback to be less than smooth. This is because as Todd mentions, the playback rate is driven by the audio portion of the file for sync, not the video. The Mac OS will always treat the audio as a priority.

2. Running the audio and video on separate files on different layers will potentially yield the best result for smooth video playback but then this is where we run into the "lip sync" problem. I typically run the audio from a different server dedicated just for that purpose.

Here is what I have discovered since:

1. Running the audio and video independent of each other works wonderfully if the media was created at a specific frame rate and your display is running perfectly at that rate. ie: When I have the media at 30fps and connected to monitors that are at a perfect 60Hz refresh rate, I can achieve perfect sync.

2. 60Hz is not always that. On most systems (Spider, Encore, Etc.) or even large displays and projectors, the true refresh rate will be 59.94. Even when your display settings are set to 60Hz in both the system settings as well as Catalyst, your output frequency will be adjusted to that of the display your connected to thanks to EDID management through DVI. This is easily verifiable when you look in the Stats window in the HUD.

Here is my plan to fix the problem next time around:

1. Use a DVI detective to capture the EDID from the monitors that work and force the video card to stay at those settings when connected to other systems.

2. Continue to run audio and video independently so that the video playback will be as smooth as possible.

3. Be more cognizant of the refresh rates that the Catalyst is capable of.

The playback pro doesn't seem to have this problem. I am really curious to know what they do to correct this and provide solid, clean playback. That is a Mac based system too for anyone that doesn't already know and is responsible for taking over when Catalyst has failed me in the past with this.

There are a couple of products on the market that are actually designed to deal specifically with this problem. The DVI parrot is one that comes to mind that is designed to "prevent display misunderstandings" as their literature says.

[pip]

Was up last night testing different mov files (photo jpeg, AIC... 25/30fps) on different versions of catalyst (4.10 - 4.40) running 10.5.8 + 10.6.7! Then got some sleep.

Im still finding dropped frames when using the audio play mode as mentioned in this thread. Looking at the stats its the middle 'pink' bar on the layers play graph that spikes (as mention before) causes the dropped frames and stutter.. be good to learn what this represents?

I also split video/audio on another layer and

• a) triggered both play setting at the same time... video was one second behind by the end of the clip
• b) synced them by local ID
• c) ran Catalyst on another MacPro (no dongle) running just the audio and remote synced the two together. MacPro with the DV dongle was the master.

I did notice the screens i have been using are fixed to 60Hz and the cinema display 59.XX.

Will be using a TH2G with LX41 and Lighthouse R7 LED come the show in a weeks time!

Not looked into Playback Pro yet, will do, but did run the 25/30FPS versions on Qlab and that showed no problem. Least i have a backup, but need the functions of Catalyst.

[pip]

If anyone wants to see if its the content i personally am using... i have cropped a section if it would help??

http://bradeng.com/tmp/001%20Test%20Cropped.zip

Screen recording... Note at 15FPS!

http://bradeng.com/tmp/scr_rec.mov

[samsc]

Just found that running the audio from the same layer causes the playback to jitter and a 'spike' in the mov 1 play reading in the stats hud...

Attached video: http://www.youtube.com/watch?v=wkmajfu0wdA

This does not happen when using an non-audio play mode. I take it this could be a graphics card problem? Will look at replacing the cards tomorrow.

'spiking' is normal - this is audio being buffered

[samsc]

what screens and what screen sizes?
what catalyst playback frame rate?
screen 1 div 2? screen 2 div 2

-

'spiking' is normal

the usual problem is not drop frames at all - but screen refresh rates that do not match the audio/video frame rates
the 'visual' stutter isnt what people think - there isnt any stuttering - the screen just isnt displaying the image because the movie frames display times dont match screen refresh times

when doing audio - you have to work differently -

the frame rate of movie needs to match frame rate of screens -

triple heads are particularily obnoxious for this

-

screens dont run at 60Hz or exactly 75Hz -

Was up last night testing different mov files (photo jpeg, AIC... 25/30fps) on different versions of catalyst (4.10 - 4.40) running 10.5.8 + 10.6.7! Then got some sleep.

Im still finding dropped frames when using the audio play mode as mentioned in this thread. Looking at the stats its the middle 'pink' bar on the layers play graph that spikes (as mention before) causes the dropped frames and stutter.. be good to learn what this represents?

I also split video/audio on another layer and

• a) triggered both play setting at the same time... video was one second behind by the end of the clip
• b) synced them by local ID
• c) ran Catalyst on another MacPro (no dongle) running just the audio and remote synced the two together. MacPro with the DV dongle was the master.

I did notice the screens i have been using are fixed to 60Hz and the cinema display 59.XX.

Will be using a TH2G with LX41 and Lighthouse R7 LED come the show in a weeks time!

Not looked into Playback Pro yet, will do, but did run the 25/30FPS versions on Qlab and that showed no problem. Least i have a backup, but need the functions of Catalyst.

[samsc]

the solution to perfect audio and video requires

a very different approach - audio takes total priority- not video

you run a single layer only - and run the catalyst video frame playback rate at 60fps or 75fps - not 25 or 30fps - see attachment
( lock to screen 1 divide 1 or lock to screen 2 divide 1 )

dont use triple heads -

only use a single output from computer

never have mismatched monitor sizes on different outputs

-

i think you will find that playback pro is basically - 1 or 2 layers - with only 1 output
not triple heads- not 32 layers - not mixed screen outputs etc
not all the fx -

Okay, I have a few thoughts on this subject. I have had these problems on many occasions and have yet to find a solid solution for it.

Here is what I understand:

1. Running the video with an audio play mode when they are merged together in the same file can cause playback to be less than smooth. This is because as Todd mentions, the playback rate is driven by the audio portion of the file for sync, not the video. The Mac OS will always treat the audio as a priority.

2. Running the audio and video on separate files on different layers will potentially yield the best result for smooth video playback but then this is where we run into the "lip sync" problem. I typically run the audio from a different server dedicated just for that purpose.

Here is what I have discovered since:

1. Running the audio and video independent of each other works wonderfully if the media was created at a specific frame rate and your display is running perfectly at that rate. ie: When I have the media at 30fps and connected to monitors that are at a perfect 60Hz refresh rate, I can achieve perfect sync.

2. 60Hz is not always that. On most systems (Spider, Encore, Etc.) or even large displays and projectors, the true refresh rate will be 59.94. Even when your display settings are set to 60Hz in both the system settings as well as Catalyst, your output frequency will be adjusted to that of the display your connected to thanks to EDID management through DVI. This is easily verifiable when you look in the Stats window in the HUD.

Here is my plan to fix the problem next time around:

1. Use a DVI detective to capture the EDID from the monitors that work and force the video card to stay at those settings when connected to other systems.

2. Continue to run audio and video independently so that the video playback will be as smooth as possible.

3. Be more cognizant of the refresh rates that the Catalyst is capable of.

The playback pro doesn't seem to have this problem. I am really curious to know what they do to correct this and provide solid, clean playback. That is a Mac based system too for anyone that doesn't already know and is responsible for taking over when Catalyst has failed me in the past with this.

There are a couple of products on the market that are actually designed to deal specifically with this problem. The DVI parrot is one that comes to mind that is designed to "prevent display misunderstandings" as their literature says.