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qt v compressor mpeg 2 export

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peter rooney
qt v compressor mpeg 2 export
on Jul 5, 2005 at 11:29:24 am

Hi folks, . I'm experimenting with compressor and at the moment my QT mpeg 2 export is doing my exports as follows. 2 to 7 one pass vbr and taking app 2hrs. The exact same encode rate in compressor is taking 10 hrs!!!!!
When I burned the same projects onto dvd I couldn't tell them apart.
What is compressor doing or what is it offering that would be worth losing my mpeg 2 export from QT 7


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Charles Simonson
Re: qt v compressor mpeg 2 export
on Jul 5, 2005 at 7:47:11 pm

2 to 7 one pass vbr and taking app 2hrs.
What does this mean? Can you provide more (exact) details as to the settings of your encodes for each app? In Compressor, do you have the framing filters turned on?

I have seen some extremely long encode times when using some of the field and frame based filters in Compressor 2 on progressive sources. Its so bad, that it makes any encode using them unfeasible. Select None for the the framing filters, and then see if your time doesn't speed up some. As far as differences between encoders, if you can't tell the difference between a QT and Compressor encode, then there is nothing to be concerned about, and go ahead and save the time and use QT. Really, Compressor's only advantages are its batch encoding, image filters, cropping, and AC-3 encoding. Obviously, that's a lot, but if you don't need it, then just stick with QT.


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peter rooney
Re: qt v compressor mpeg 2 export
on Jul 6, 2005 at 11:26:28 am

HHMMM I didn't even knmow what framing filters were, 2 and 7 refer to target bitrate and max bitrate, I simply selected from a list of templates in compressor. But as you say, if I can't tell the difference by the time it hits the TV then what do I need Compressor for.
Peter


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Charles Simonson
Re: qt v compressor mpeg 2 export
on Jul 7, 2005 at 3:40:26 am

The frame controls are located in the third tab from the left in Compressor 2's settings Inspector window.

As far as 2 and 7, there should be no template provided from Apple that sets the target bitrate to 2mbps (the lowest I see is 3.7mbps). For full frame MPEG-2, if your video was actually encoded that low, then it would look terrible. The only way MPEG-2 at 2mbps can look at all decent is if it were encoded to 352x480. Which I doubt you did. Which may also explain why your target rate was so off. It sounds like Compressor decided that you made a mistake in your settings, and instead of abiding by your input, encoded to what it suspected was needed.


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Charles Simonson
Re: qt v compressor mpeg 2 export
on Jul 7, 2005 at 3:42:41 am

Please excuse the last few sentences of my previous post, I got your post and the topic below interchanged.


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Charles Simonson
Re: qt v compressor mpeg 2 export
on Jul 7, 2005 at 3:57:59 am

I see from the templates that Apple provides that the Frame Controls are set to Automatic. Try duplicating the preset and then set the Frame controls to None. Then do an encode to test the time. Then activate whatever filters you may want to use one-by-one, and keep re-encoding to see what is causing the time disparity.


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peter rooney
Re: qt v compressor mpeg 2 export
on Jul 7, 2005 at 1:55:56 pm

Thanks for your input Charles, experimenting with the settings is clearly an option but it's all taking so painfully long and tying up my mac.
Someone posted a link to a hardware encoderf for mpeg2 by LaCie and that does it in realtime but it's ntysc only Its made me curious though. Phillips make a DVD recorder and I'm surre there are a lot more of them out ther but it seems simply to dump the encoded footage onto disc, where I'd like a digital file so I could finish the job. If folks are already makiong DVD recorders for consumers which encode for mpeg onto disc surely there must be more products out there which could give me an mpeg file AND do the job in realtime.


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Ben Waggoner
Re: qt v compressor mpeg 2 export
on Jul 14, 2005 at 3:12:33 pm

A dual G5 can convert from DV to MPEG-2 faster than real-time, so you should be able to get to the speed you need.

Most of the hardware direct-to-DVD encoders I've seen have been pretty lousy in terms of quality. I like the control of being able to tweak the settings to get it right, and especially to handle 2-pass encoding.


My Book: http://www.benwaggoner.com/books.htm
Squeeze and ProCoder tutorials: http://www.classondemand.net/benwaggoner/
Compression Class at Stanford: http://www.digitalmediaacademy.org/compression.html


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