Bitrates: How Long Should the Prediction Take? - digitalFAQ.com Forums [Archives]
 digitalFAQ.com Forums [Archives] Bitrates: How Long Should the Prediction Take?

#1
08-02-2003, 01:48 PM
 ak47 Free Member Join Date: Oct 2002 Posts: 168 Thanks: 0 Thanked 0 Times in 0 Posts
I tried Cqmatic 1.02 a while ago on Rush Hour 2 which is 90mins, and I think the results were about 10 minutes. Then later I tried a Spirited away an anime that is 124min. But when I did Spirited away the movie took almost as long as to predict to encode. I was wondering how long should it take compared to a full encode (%). By the way I am using mpeg-2 and gop of 12 and 3000max and 64min bitrate and 544x480 resolution everything else is the same as the templates.

Just for the heck here are my specs of my computer.

AMD XP 2500+ OC to 2800+
Coolmaster HHC-001
MSI K7N2G-L
Integrated video
512mb and a 256mb Corsair pc 2700 Low latency
Seagate 60GB
West 160 gb
ANTEC SOHO Model SX1040BII with 400 Watt Smart Power
LiteOn 52x24x52
Total of 7 fans in the tower
Someday, 12:01 PM
 Site Staff / Ad Manager Join Date: Dec 2002 Posts: 42 Thanks: ∞ Thanked 42 Times in 42 Posts
#2
08-02-2003, 02:59 PM
 kwag Free Member Join Date: Apr 2002 Location: Puerto Rico, USA Posts: 13,537 Thanks: 0 Thanked 0 Times in 0 Posts
Hi ak47,

The prediction should take no more that ~15% of the total time of the movie. However, if the final CQ will fall in the unlinear range (varies if CQ or CQ_VBR), then it can take WAY longer, because there's just no way to calculate
So the best thing that CQMatic be do, is start bracketing down (or up) on CQ values, until the target is reached. In another way, say I want a target sample of 10MB. I encode with a CQ of 50 and I get a 20MB sample. If TMPEG's CQ was linear, then simply dividing by 2 (50/2) would give me a 10MB sample, but this is not the case, and I can wind up with 14MB. So you see, it's a real pain to calculate the correct target, and every CQ value creates a different file size completely out of proportion.
So the best you can do is ~2 passes, to a max of "I don't know", depending on your material.

-kwag

 Similar Threads Thread Thread Starter Forum Replies Last Post Abond Avisynth Scripting 136 07-05-2005 02:13 PM m0rdant Video Encoding and Conversion 6 08-14-2004 10:17 AM KYUSS Video Encoding and Conversion 2 02-03-2004 05:22 PM StayAlive Video Encoding and Conversion 4 10-21-2003 06:52 AM Bchteam Video Encoding and Conversion 7 08-03-2003 12:23 PM