Video playback with Audio. Sync error?

[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.

[Mr_P]

possibly - but what are the specs of your movie?
what codec and data rate - this could also be a factor?

s

[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...

[Mr_P]

Richard - a question:
In a show scenario with some content with audio and some without

- How do you change the playback from 'lock to screen div 1' back to a rate that works for the rest of the non-audio content using a non-audio playmode?

Do you have to go and change it in the catalyst control window or via the web server?
or
should you just use the speed control to slow playback of the non-audio files?

S

[samsc]

Richard - a question:
In a show scenario with some content with audio and some without

- How do you change the playback from 'lock to screen div 1' back to a rate that works for the rest of the non-audio content using a non-audio playmode?

Do you have to go and change it in the catalyst control window or via the web server?
or
should you just use the speed control to slow playback of the non-audio files?

S

look in the safari activity log when you access the pull down menu in cat web server-

changes the frame rate via web commands
http://xxxyourcomputer.local.:8080/c...=61,0,500,31,0
http://xxxyourcomputer.local.:8080/c...=61,0,500,32,0
...

-

the performance is far lower at 60Hz- its really only for emergencies when audio syncing is THE most important thing- or you have one or two layers
normal shows will very rarely run well at 60Hz - if at all.