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Another "External Monitor Out of Sync" Question

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Greg Newman
Another "External Monitor Out of Sync" Question
on May 17, 2011 at 6:18:06 pm

This nagging Frame Offset issue....

My system:
MacPro 2x2.66Ghz Quad Core
AJA Kona LH running video out to a Flanders HD monitor, using 1080p 23.98 8bit setting.
Audio runs out through Kona to a mixer and then to external speakers.

I know from the many discussions on this board and elsewhere that FCP's Playback Frame Offset is there to delay playback of both video and audio to compensate for the processing latency inherent in many external monitoring systems.

However, my problem is that the video on my monitor is delayed while the audio is not. No frame offset value will fix this, as it merely delays both video and audio together at the computer.

The only way I can watch my external monitor in sync is to slide all video back 4 frames on my timeline before I playback to view on that monitor. Then I have to remember to slide the video back into place to continue editing. I've found this to be the case on many edit systems in many facilities, using a variety of monitoring systems, graphics cards and settings, and no one has been able to suggest a fix.

Because of this, I can't use the external monitor while I'm in editing mode, because it is out of sync and delayed from the video on my computer.

Anyone have any suggestions for this fix? What am I missing?

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David Roth Weiss
Re: Another "External Monitor Out of Sync" Question
on May 17, 2011 at 7:02:28 pm

I'm sorry Greg, but what you're saying above can't be accurate. Many of us have exactly the same hardware/software and do exactly what you're doing, however resetting the frame offset from it's default of "4" to "0" takes care of the 4-frame latency or more precisely "non-latency" issue. I suggest you try it again, because you could not be the only one for whom it does not work.

Let me add to the above by say that Bram Desmet from Flanders Scientific is due over here at my place in three hours. I'll confer with him on this and will make sure that I'm not overstepping above, as the one variable I don't have here at present is one of his monitors.

David Roth Weiss
David Weiss Productions, Inc.
Los Angeles


A forum host of Creative COW's Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.

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Greg Newman
Re: Another "External Monitor Out of Sync" Question
on May 17, 2011 at 7:13:47 pm

Thanks David, let me describe a test I'm doing here to see if I explained things accurately in my original post:

Frame Offset = 0
Press Play
Canvas plays immediately and in sync
Timeline plays immediately and in sync
Audio Mixer levels visually match timeline and the sound from my speakers
Video on my external monitor appears 4-6 frames behind video in my canvas and the audio I hear.

Frame Offset = 30
Press Play
Canvas does not begin to play for 30 frames
Timeline does not begin to play for 30 frames
Audio Mixer levels play immediately and match the audio in my speakers, which also plays immediately.
Video on my external monitor plays immediately but still appears 4-6 frames behind the audio I hear.
30 frames after pressing Play, the canvas and timeline begin playing, though the audio and external video are already 30 frames ahead of them.

My conclusion from this test is that the frame offset delays playback at the canvas and timeline, but still sends video and audio out through the Kona card without delay, and sends them together.

If you repeat this test on your system and get different results I'd love to know them, and figure out why I'm getting these results. Or, if my original post or this test reveal something I'm fundamentally wrong about I'd love to know that too - all I want is a solution and to understand what I'm doing wrong.


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Bram Desmet
Re: Another "External Monitor Out of Sync" Question
on May 17, 2011 at 8:04:53 pm

Couple of tips on the monitoring side of the equation:
1. Make sure the video processing mode of the monitor is not set to noise reduction, this adds significant processing delay.
2. Many customers that just need to monitor stereo audio use the monitor's built in disembediing capabilities because the monitor will automatically delay the disembedded audio by the exact amount of video processing time. Granted this is unbalanced audio on a mini-jack connector, but for smaller edit suite environments this can work well as an inexpensive way to ensure perfect audio sync.

Again, this may be just a part of the equation because to my knowledge a lot of customers use the playback offset feature to achieve proper sync as well.

Bram Desmet
FSI (Flanders Scientific, Inc.)

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Victor Perez
Re: Another "External Monitor Out of Sync" Question
on May 17, 2011 at 8:31:30 pm

I had sort of a similar problem when the Audio Video Settings audio playback selector was changed to line out instead of my AJA Kona.

In FCP's Audio Video Settings - make sure the Audio Playback selector is designating your card as the output device.

Hope that helps,


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Greg Newman
Re: Another "External Monitor Out of Sync" Question
on May 17, 2011 at 9:14:46 pm

SOLVED! Sort of...

Keith at AJA sent me steps to trash preferences, reboot and reset Kona and FCP. I've copied those instructions at the bottom of this post.

These steps helped, but the process illuminated what was actually the main problem: In FCP my video playback settings were:

Kona LH 1080p 23.98 8 bit

If I switched those to:

Kona LH 1080psf 23.98 8 bit

then playback was in sync. However, the image on the monitor was jittery and splotchy, as if compressed.

If I switched FCP playback settings to:

Kona LH 720p 59.94

then playback was in sync and the monitor looks fine.

SO... unless the Flanders people have another suggestion, I'm concluding that the monitor was causing too much processing delay at 1080p to stay in sync with the audio.

Also, I've set my Frame Offset to 3. All seems to work fine now.

Except for another oddity I'd like to propose here for review:

If I load a clip into the Viewer that has a distinct audio hit, such as a camera slate, and I view the audio waveform in the viewer while playing the clip, the audio plays out of the speakers about 5 frames after the cursor passes the slate's waveform in the viewer. This is problematic when making precise audio edits.

If I view that same clip in a sequence, the audio playback perfectly matches the position of the cursor in the timeline, syncing with the waveform perfectly.

If I switch my external video to OFF, the clip in my viewer now shows to be in sync with the sound in my speakers. I switch it back to All Frames and the audio is now again about 5 frames behind the waveform in the viewer.

None of this involves viewing the external monitor at all, this is just viewing playback on the computer monitor and running audio out to the external speakers.

This oddity is unaffected by any frame offset, or video playback setting. It is merely present when external video is set to All Frames, and gone when external video is set to Off, even though the oddity only occurs on the computer monitor, in the Viewer.

If anyone has any suggestions on this one, let me know. Meanwhile, here are the reset instructions from Keith at AJA:

1) Delete the Kona preferences:
a) Go to Mac HD: /library/preferences/ and delete all the com.aja.* files.
b) Go to Mac HD: /users/username/library/preferences and delete com.aja.KonaControlPanel.plist.
c) Reboot
d) Restore the AJA Control Panel settings.
2) Reset the computer PRAM:
a) Turn off the computer.
b) Turn on the computer and immediately hold down:

c) Release after the third boot-up alert.
3) Delete the Quicktime preferences:
a) Go to Mac HD: users/username/library/preferences/
b) Delete
c) Delete a file called: "quicktime preferences."
d) reboot.
4) Delete the FCP preferences:
a) Close FCP
b) Go to Mac HD: users/username/library/preferences/
c) Delete
d) Drag the FCP user data folder to the desktop.
e) Restart FCP and setup with a AJA easy setup.

1) Go to FCP system settings -> playback control:
a. Set video quality to HIGH.
b. Set frame offset to 1
c. Uncheck scrub high quality
2) Go to FCP user preferences -> and make sure audio quality is set to LOW (48Khz sampling).

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Bram Desmet
Re: Another "External Monitor Out of Sync" Question
on May 18, 2011 at 3:23:19 am

Hi Greg, please note that one playback offset value will not work for all formats. The video processing delay of most LCD monitors that sync to the native vertical frame rate of the source is a function of the number of frames/fields per second. What this means is that in higher frame rate material the video processing delay is shorter (in ms) vs lower frame rate material. Basically this results in exactly what you were seeing: in your 60 frame material (720p60 in your example) you will have the lowest processing delay, followed by your 24psf material (keep in mind this is fed to the monitor as 48 fields), and then lastly your 24p material. The fewer frame/fields per second you have the longer the video latency vs audio in milliseconds. This is not a function of the monitor's processing power, but rather just a function of the frame rate of the source.

What this all means is that if using a standalone line delay or playback offset you will need to adjust those values based on the processing mode the monitor is in (fast, normal, or noise reduction) and the frame rate of the incoming source.

As mentioned earlier when dealing with just two channels of audio (stereo) many people just use the audio out of the monitor because that automatically delays the audio by the exact amount of video processing delay, regardless of incoming frame rate or monitor processing mode.

Bram Desmet
FSI (Flanders Scientific, Inc.)

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