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-   -   DVD2SVCD: DVD2SVCD file size prediction for CQ_VBR (http://www.digitalfaq.com/archives/encode/1767-dvd2svcd-dvd2svcd-file.html)

black prince 12-04-2002 07:32 PM

DVD2SVCD: DVD2SVCD file size prediction for CQ_VBR
 
Hi All,

DVD2(K)VCD when setup properly produces great encodes. I noticed that when D2V performs file size prediction for CQ_VBR, it performs a lot of tests (see sample below) to arrive at the optimal CQ. It tests well beyond CQ=100 until eventually it defaults to 100? In my manual process I use mid-point testing to arrive at a optimal CQ. On average it takes me 4 to 6 passes to achieve the same CQ as D2V. Mid-point testing is finding the mid-point of a test range and determining whether the target file size lies in a higher or lower mid-point range until the range can not longer be divided. For example, my starting range is 20 to 100. I chose 100 because this is the max of Tmpgenc. The mid-point between 20 to 100 is 60. I test file size prediction starting with 60 and if the result is less then target file size ( CD size minus audio file size) then I use the the mid-point range of 60 to 100 or 80. This is now pass-2. Next, if the result of 80 is still less than target file size then the next mid-point range is 80 to 100 or 90. If the target size is still less, then next mid-point is 95 until I can no longer calculate a whole number mid-point, I default to 100. My manual process took 5 passes, but D2V took many more. I’m also testing a way to reduce test passes down to 3 to 5 by using movie length (in minutes) and aspect ratio (4:3 vs 16:9) to determine my starting point. For example, if a movie is between 60 to 90 minutes and has an aspect ratio of 16:9 (wide screen) then CQ could start at the mid-point between 20 to 60 or 40. Only after many encoded movies and storing this info in a spreadsheet table will I get a sense of whether this information could be useful.

My question is can my way of calculating CQ_VBR somehow be substituted in D2V or can another way of calculating be used to improve this process.

From dvd2svcd_log.txt

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315619105 (1284784kb) Using CQ Value: 62.00
Calculated next CQ Value: 70.74Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315805848 (1284967kb) Using CQ Value: 70.74
Calculated next CQ Value: 80.71
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315646597 (1284811kb) Using CQ Value: 80.71
Calculated next CQ Value: 92.08
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315698515 (1284862kb) Using CQ Value: 92.08
Calculated next CQ Value: 105.06
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315695502 (1284859kb) Using CQ Value: 105.06
Calculated next CQ Value: 119.87
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315634815 (1284800kb) Using CQ Value: 119.87
Calculated next CQ Value: 136.77
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315692543 (1284856kb) Using CQ Value: 136.77
Calculated next CQ Value: 156.04
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.

- Encoding Test Clip D:\Temp\AviSynth_Script_file_CQ_TEST.avs
Wanted: 1531546008 (1495650kb) Predicted: 1315712073 (1284875kb) Using CQ Value: 156.04
Calculated next CQ Value: 178.03
Executing TMPGEnc. Commandline:
"E:\DVD BACKUP\2 - DVD2SVCD\TMPGENC PLUS\TMPGEnc.exe" "D:\Temp\TMPGEnc_Project_file.tpr" /Encode /Close
Video Encoding finished.




BTW, I am using DVD2SVCD 1.1.0 build 1c, Blockbuster 0.5, FluxSmooth 0.4, LegalClip 0.2, and AutoCrop.



-black prince


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