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Old 14 Dec 2002, 02:40 AM   #1
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Default Question about second pass

I have done First Pass and in the end of it - I got a log file (6 mb) and a small avi file (1.5 mb) - What are they ???

(after That I make a Pass 2 based on those files...)

another question: Is there a difference between using second Pass methode and quality based-quantizer methode?
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Old 14 Dec 2002, 08:50 AM   #2
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Default Re: Question about second pass

Quote:
Originally posted by Nadav
I have done First Pass and in the end of it - I got a log file (6 mb) and a small avi file (1.5 mb) - What are they ???
The .log file contain information about how well each frame compresses. This information is used during the second pass.

The .avi file, is just an invalid avi file, created because the encoder has to produce some output. It isn't used for anything, and can safely be overwritten by the second pass.

Quote:
Originally posted by Nadav

another question: Is there a difference between using second Pass methode and quality based-quantizer methode?
Yes.

I suppose you might want to ask "what is the difference ?".
The difference is that quality based encoding, encodeds all the frames at the same quality setting. This may produce wildly unpredictable filesizes.
2-pass encoding tries to encode the movie at the specified bitrate (average bitrate for the whole movie). Bitrate controlled encoding also encodes low-motion scenes at a higher quality setting than high motion scenes. This is because image quality is more noticeable durring low-motion scenes.
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Last edited by khp; 14 Dec 2002 at 08:53 AM
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Old 14 Dec 2002, 09:03 PM   #3
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Talking-2 Thanks, and ....

Another question :

When I choose the bitrate in divx 5 codec, Is this the Highest biterate to use or the average bitrate?

when doing pass1 - do I need to set the bitrate ? or should I do it in the second pass and use calculator?
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Old 14 Dec 2002, 10:35 PM   #4
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it is the average bitrate

pass number one analyzes the video stream and thus doesnt care for any bitrate setting
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Old 15 Dec 2002, 03:49 AM   #5
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Default OK, What about pass 2 ?

Do I need to set bitrate?

I mean if the first was to analyze so the second pass is using the analyze.log file from pass 1 to encode and so that the information about bitrating is given from the log file - so I don't need to set bitrate in the second pass, True ?

Hope you'll understand what I wrote
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Old 15 Dec 2002, 04:10 AM   #6
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you WILL HAVE TO set the bitrate for pass 2!!!
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Old 15 Dec 2002, 04:43 AM   #7
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Quote:
Originally posted by UncasMS
pass number one analyzes the video stream and thus doesnt care for any bitrate setting
That is not entirely true, in divx5 the bitrate setting does affect the first pass, but it's OK to change it, upto about 30% before doing the second pass.
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