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Compressor not restricting data rate.

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Tyler Dixon
Compressor not restricting data rate.
on Apr 18, 2008 at 1:07:49 am

I have some clips I need to export to the web using H.264, and I'm using Compressor. I need to have the data rate restricted to 1500kbits/s for the site. I've set it that way in Compressor. The trouble is, the video file always comes out with a data rate of 3mb/s (3000kb/s) or right around 3. I've tried it through a custom-made droplet and just doing it regularly though Compressor. I've verified multiple times that everything is set correctly, and I've tried it on multiple computers (Two 8-cores and a Quad). Tried trashing Compressor plist, restarting and making a completely new setting.

Here are the settings I'm using:

Best Quality Audio 48k

Video- QT, 720x360, Pixel Aspect Ratio: Square, Crop: None, Padding:None, Frame Rate 100% of source, H.264 Codec, Multi-pass, Average data rate 1.536 (Mbps), Fast Start on Compressed Header, Watermark.

Thanks in advance.



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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 3:46:03 am

I'm running comparisons in Quicktime and Compressor now. If I set the "Restrict data rate" in Compressor to 1500kbps, the Quicktime file I get is actually around 3mbps. If I set it in Compressor to 750kbps, The Quicktime file I get is 2.3mbps. By setting it in Compressor to a meager 100kbps the Quicktime comes out right around 1500kbps, but it looks really awful. I can get it pretty close to what I want by setting Compressor to 300kbps, and the Quicktime comes out at around 1800kbps, which I may be able to get away with, but I'd still like to know what exactly is happening.

Any ideas?



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Daniel Low
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 10:13:55 am

Can you confirm that you are using CBR, not VBR in compressor?

How did you arrive at a frame size of 720x360?


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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 11:37:00 am

I don't really know, there doesn't seem to be anything regarding variable or constant in Compressor, only a restriction. And I think it's logical to assume that means "Don't go above x amount."

As for frame size, I'm working from a RED proxy that was originally 1024x512 (the medium one), and I needed to make it smaller for the web, so I made it 720x360 in order to keep the same 2:1 ratio.



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Daniel Low
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 12:17:55 pm

My bad, there is no CBR/VBR for H.264.

Can I assume that you have tried setting both the Average and Maximum datarate sliders to 1500kb/s?




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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 12:28:36 pm

Well, I have only two options for data rate: "Automatic" and "Restrict to", for which you can type a numerical value. No sliders anywhere.



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Daniel Low
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 1:42:09 pm

I think you are looking at the Quicktime export windows options, not in compressor. What version of compressor are you using?

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Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 1:56:12 pm

I'm using the latest version of Compressor. I'm looking in the Video Settings under the Encoder tab in the Inspector window.



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Daniel Low
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 2:10:19 pm

OK. Have you tried the alternative H.264 method as described in chapter 11, specifically on page 155 of the compressor user manual?

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Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 2:45:02 pm

It looks like that method that's in the manual is only for the DVDSP method of compression. I can't seem to alter frame size or change audio settings.



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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 2:49:02 pm

Sorry for the double post, but I forgot to add that I need to have it be a Quicktime movie, and that's another reason I can't use the DVDSP method.



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Daniel Low
Re: Compressor not restricting data rate.
on Apr 18, 2008 at 2:53:29 pm

Mmmm....

Try giving the demo version of Episode a try and see if it has the same rate control issues:

http://www.flip4mac.com/episode_download.htm

I can't think of anything else to try.

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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Ben Waggoner
Re: Compressor not restricting data rate.
on Apr 19, 2008 at 3:13:43 am

Episode has historically been a better H.264 encoder than Apple's, although I haven't done a head-to-head recently.

Episode also supports HIgh Profile H.264, which QuickTime can now play back, although it still can't author.

Stay away from HE AAC for audio, though, as it'll sound lousy in QuickTime.

Ben Waggoner
Principal Video Strategist, Silverlight
Microsoft Corporation

Compression Blog: on10.net/blogs/benwagg/
Compression Classes at Stanford and PSU: on10.net/blogs/benwagg/21622/


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Tyler Dixon
Re: Compressor not restricting data rate.
on Apr 20, 2008 at 4:17:27 am

I was playing around in the demo for it, and a twelve second clip that I rendered in Compressor and Episode rendered twice as fast as it did in Compressor. Though, I couldn't get the watermark to work for some reason. It would be very nice to have, what with the H.264 files I need done for this project, but I don't know if I'll have any other projects like this, so I don't know if it's worth $849, since it doesn't seem to support 10bit uncompressed or ProRes. But thank you for the suggestion; I'll keep it in mind.

The 1.8mbps files I'm outputting now are working fine, but it's still weird that it's doing what it's doing.



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