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  #1  
02-09-2013, 12:51 AM
JasonCA JasonCA is offline
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I'd like to explore setting up the ATI 600 USB correctly under Windows 7.

So far, I have no issues using VirtualDub and the ATI 600 USB together under windows 7 (64-bit). I can see video and can capture video too (thank you DigitalFaq for the drivers and tutorial on how to set that up). So far so good....

However, I notice slight video delays when I am in capture mode and just have Video->Overlay enabled. Here, I can just watch the video (without capturing). And, when watching...I can sort of observe video timing issues...or jitter...or slight pauses in the video here and there.

When I begin to capture, although it looks relatively smooth, the slight pauses increases.

First, what is the purpose of the "Timing Graph". I've attached a snapshot of my timing during capture. Can I use this graph to help determine if my ATI 600 USB is capturing the video correctly? What does a healthy timing graph look like?

Or, what's the best way to help to ensure I don't have glitches and/or timing issues in the video capture? There must be a good way to verify that my stream of video that I am capturing is writing cleanly to the hard-drive without jumps and pauses.


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  #2  
02-10-2013, 03:09 PM
robjv1 robjv1 is offline
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Just to clarify -- these glitches are only showing up when previewing via the overlay right? They aren't showing up in the actual captured file?
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  #3  
02-10-2013, 04:41 PM
JasonCA JasonCA is offline
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Quote:
Originally Posted by robjv1 View Post
Just to clarify -- these glitches are only showing up when previewing via the overlay right? They aren't showing up in the actual captured file?
Hey Robjv1...

Thanks for the response.

The glitches are showing up in the captured stream. Watching the video, I can see in motion where things pause or suddenly accelerate. And that's all I can do...watch the video.

To help fix this, I had to go to Capture->Disk I/O and bump up my Chuck size and Chunks In Buffer. After this, it was MUCH better. However, now and then I still get pauses.

Furthermore, if I leave on "Drop frames when captured frames are too close together", and look in the lower left corner of virtual dub I would see:

"357 frames (25 dropped), 13.100s, 2ms jitter, 2ms disp, 689287 frame size, 242635K total: 1.0030259"

As you can see, I've dropped frames! Also, my file size doesn't seem to grow all that fast.

But, if I disable the "Drop frames when captured frames are too close together", then I don't drop frames. However, I'm not sure why I have to disable this?

But even still, I'm not quite sure how to determine if I truly am loosing frames? Do I rely on reading "(0 dropped)" in the lower left corner of virtualdub to verify that I didn't drop frames?

If I am loosing frames, what's the best indicator of this? And if I am not losing frames, how do I know it's not a duplicate frame too?
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02-10-2013, 09:03 PM
robjv1 robjv1 is offline
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It's easy to tell when you are dropping frames, because they'll be missing when you watch the video of course, it'll add a noticeable judder to the video. It doesn't sound like you are dropping frames.

Maybe I'm not quite understanding what you are saying, but the speeding up and pausing sounds like the timing settings for sure -- keep in mind that with that card the audio and video should be locked together, so you don't have to worry about compensating for timing differences.

For the ATI they should look like the attached picture.

As long as your computer is powerful enough, that should result in no dropped frames and no sped up / slowed down video and audio.


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File Type: jpg Virtualdub Working Timing Options.jpg (170.6 KB, 297 downloads)
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  #5  
02-10-2013, 10:16 PM
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Sometimes the Overlay doesn't work properly, and its best to use the Preview option instead. Also make sure to not preview with audio, it can cause some problems as well.

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  #6  
02-12-2013, 09:21 PM
JasonCA JasonCA is offline
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Great! Thanks a lot robjv1! Wow, my settings were much different. And, this has helped to improve my video transfer. So from the small testing I've done, this works! So I thank you!

Quote:
Originally Posted by robjv1 View Post
It's easy to tell when you are dropping frames, because they'll be missing when you watch the video of course, it'll add a noticeable judder to the video. It doesn't sound like you are dropping frames.
Right, you can often tell when you are dropping frames! However, this isn't really good enough. What if I recorded 2 hours of video? I can't obviously watch the entire thing. So, there must be a better way to determine if I have dropped frames? What I'm getting at is, can I trust Virtualdubs dropped frame status? The format in the lower left corner is as follows:

"357 frames (25 dropped), 13.100s, 2ms jitter, 2ms disp, 689287 frame size, 242635K total: 1.0030259"

It would be great if someone could break each field out? Here we got dropped frame count, time??, jitter time??, time of 'disp' (whatever that is), ...etc.

There's jitter time shown in the "Timing Graph" (Capture->Timing Graph). But what does this jitter time really mean to me when I see it fluctuate? Big deal? How does the jitter time relate to the quality of the video being captured? How concerned should I be?

But again, can I rely on the frame drop count? Does it accurately reflect when a frame was lost? I ask this, because when I had "Drop frames when captured frames are too close together" enabled, I would immediately start dropping frames. Soon as I disabled "Drop frames when captured frames are too close together", I no longer was receiving dropped frames. I wondered if "Drop frames when captured frames are too close together" perhaps disables the accuracy of the drop frame count? Or maybe not?

Quote:
Originally Posted by robjv1 View Post
Maybe I'm not quite understanding what you are saying, but the speeding up and pausing sounds like the timing settings for sure -- keep in mind that with that card the audio and video should be locked together, so you don't have to worry about compensating for timing differences.
At this point, I am not even passing audio through the ATI 600 USB. I see the video 'was' already jerky, and so that to me made the audio irrelevant at the time. It's just to say that I have yet to actually try audio NOW that I actually have what looks like a steady and consistent stream of video.

Otherwise, you made another great point: The audio and video should be locked together! I suppose that's because the video and audio go into this ATI 600 USB and come up through the same USB stream in sync. I never really thought of it...but that's how I look at it.

Quote:
Originally Posted by robjv1 View Post
For the ATI they should look like the attached picture.
Again, thank you for taking your time to provide these settings!

Quote:
Originally Posted by robjv1 View Post
As long as your computer is powerful enough, that should result in no dropped frames and no sped up / slowed down video and audio.
In summary, there are two things that have helped to improve my video transfer:

1) The settings you provided in the attached picture! Much different from virtualdub defaults.
2) Increasing buffer size in Disk I/O

It would be great if someone can help to clarify this "Timing Graph" a bit more. In the graph, you can see from the legend:

1) Video Time Jitter - what's the relevancy of this? How important is this? What is the healthy state?
2) Video Resampling Rate - what's the relevancy of this? How important is this? What is the healthy state?
3) Video offset error - what's the relevancy of this? How important is this? What is the healthy state?
4) Synch error - what's the relevancy of this? How important is this? What is the healthy state?

In my first post, I attached a picture of what I see in the Timing Graph. It's all over the place. Of course, this was before my improved settings. But, what's an example of a "Healthy" timing graph?
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02-13-2013, 09:25 PM
JasonCA JasonCA is offline
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I will have to play with Virtualdub more, but after using the settings robjv1 provided earlier, I only get "Video Time Jitter" status (red dots) in the Timing Graph.

Hopefully someone can help explain the Timing Graph a bit.

I've searched on the internet for virtualdub's timing graph, and there's really no description explaining it. The only thing I've seen is "Added timing graph to visualize behavior of resync engine." Well that's nice, but doesn't provide much help on how to read the timing graph or what each element is.

If anyone has found any better documentation, I'd love to read it.
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04-07-2013, 05:12 PM
jlarson2000 jlarson2000 is offline
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This thread is a little old but I'd like to reinforce what was said here since I've been flailing around with the same issue for a few days. If you are capturing with VirtualDub and the ATI 600 USB YOU MUST DISABLE VIDEO/AUDIO RESYNC!

This isn't said very often or very loudly in the many threads and guides about VirtualDub and the ATI 600, but it appears to be crucial. I'm interested in knowing if anyone thinks otherwise.

I'm new here so I'd like to thank the forum admins for providing such an excellent resource. I've been pouring over the forum for several weeks and have learned a lot. I found a new old stock ATI 600 USB and nstalled it using LS's method. Then I downloaded the pre-packaged VirtualDub from this forum and did some test captures. There were massive numbers of dropped frames, not just one or two now and then but a steady stream of between 1 to 5 every second!

I have a new screaming fast machine, solid state disk, no internal sound card, virus scanner, indexing, etc. are all off. So I'm pretty sure it isn't the environment.

From what I've read on various sites, it appears that you only need to enable audio/video resync in VirtualDub if the capture device does not combine audio and video. I don't know what this looks like at the device driver level, whether it's interleaved or timestamped, but if your capture device has connectors for both audio and video then it probably works the same way. You only need to worry about resync if you're capturing video from one device and audio is coming in from a different device like a sound card. The clocks running on the two devices will not be synchronized so VirtualDub has to compensate.

I first unchecked "Drop frames when captured frames are too close together". This solved the frame dropping problem, at least as reported in the status bar at the bottom of the capture window. But the audio and video would gradually drift out of sync. Then I noticed that "Sync audio to video by resampling..." was selected. When I changed that to "Do not resync between audio and video streams" audio and video stay in sync. The "Automatically disable resync when integrated audio/video capture is detected" may have worked too but it didn't seem to matter if you turn off all the resync options.

I'm not sure what makes VirtualDub think the streams are going out of sync, perhaps the rate of arrival isn't consistent, but it starts working very hard to compensate for a problem that isn't really there.

It's a curious default since I would imagine most people capture using a device that integrates audio and video, no?

Jeff
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  #9  
04-08-2013, 07:08 PM
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lordsmurf lordsmurf is offline
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Quote:
Originally Posted by jlarson2000 View Post
This thread is a little old but I'd like to reinforce what was said here
It's not that old. Certainly not outdated.

Quote:
I'm new here so I'd like to thank the forum admins for providing such an excellent resource. I've been pouring over the forum for several weeks and have learned a lot. I found a new old stock ATI 600 USB and installed it using LS's method.
Thanks.

And glad to hear it work.

Quote:
From what I've read on various sites, it appears that you only need to enable audio/video resync in VirtualDub if the capture device does not combine audio and video.
The ATI 600 USB is a single device, so that's odd. I'm about to make capture guides for it, so I'll see how it goes on a Windows 7 system. This has not had VirtualDub or ATI software/hardware installed on it before.

Quote:
I'm not sure what makes VirtualDub think the streams are going out of sync, perhaps the rate of arrival isn't consistent, but it starts working very hard to compensate for a problem that isn't really there.
The biggest issue with audio sync issues in VirtualDub is audio preview. Turn it off. You really can't listen to audio while you capture in VirtualDub. It's one of the downsides of the VirtualDub method.

Edit: Not actually accurate. VirtualDub settings tweaks will allow preview, though it can sometimes be poppy/cracky on said preview (but not in the actual recording).

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Last edited by lordsmurf; 08-19-2020 at 01:02 AM. Reason: Updated audio preview info.
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