Question for Pal expert

[APVM]

I have downloaded a movie in divx form, the size is about 800MB and both sound and picture is good. the resolution of the file is 604x304 and 25fps, now my question is should I convert it to pal SVCD or just pal VCD since the original file resolution doesn't seems to fit in for pal SVCD, any ideas or suggestions?

[Anonymous65]

It all depends on what quality you want. VCD is just 352x288, while SVCD is 480x576. SVCD should give you almost the same quality, while VCD will knock the quality down quite a bit. You also have to get the aspect ratio correct since the vertical resolution is not 288 or 576 in your original file.

[APVM]

How do I that (I mean the aspect ratio)?

[Lars17]

You can calculate the correct aspect ratio...

Let's see...

If you use TMPGEnc you can use the clip frame option under advanced tab, and from there adjust arrange settings.
I can calculate it for you right here:

First of all, choose to set the arrange method to "center (custom size)"

Then choose to set the size to 352*177 (VCD)
OR choose to set the size to 480*242 (SVCD)

This will let you keep the aspect ratio correct according to the resolution you said your divx-file has.

But there is one thing I would like to mention to you, and that's the fact that most TVs cut off around 5% to 10% of the picture on each side of the movie during playback, so I would recommend that you perhaps set the resolution to:

342*167 (VCD)
OR
470*232 (SVCD)

(These resolutions are to be set in the arrange method options in TMPGEnc instead of those I mentioned above.)
I can't assure you that those last resolutions will keep you from loosing anything of the movie on the sides because it varies from TV to TV, but those resolutions work quite well for me.
Let me know if you got this to work, or if you didn't I will gladly help you some more.

-Lars17-

PS: Be sure to change the size under the video-tab of TMPGEnc to either 352*288 (VCD) or 480*576 (SVCD). The resolution under the video-tab should be different from the resolution that now stands under the advance-tab because of the change in clip fram-option.

[Truman]

I am afraid the calculation is partly wrong.
SVCD 480x396 (recommended crop 604x303, resize 448x368)
VCD 352x194 (recommended 320x176)
Everything else as Lars17 said.

<font size=-1>[ This Message was edited by: Truman on 2002-01-13 15:46:27 ]</font>

[APVM]

Thank you very much for the help, the end product (SVCD) came out much better than I expected (play very well on my stand alone, picture and sound were so nice).

Now the big question here, how do you do the calculations for the resolution, is there a formula for both PAL and NTSC and where can I find it?

TIA

[Truman]

Yes, 604x303 is an aspect ratio of 1:1,9939. AVI pixel aspect ratio is 1:1.
When you resize, always add 16 pixel borders to all sides (TV overscan!), so resize to 448x544 instead of 480x576.
The following is for PAL only.
[720 x (59/54) x (448/480)] / 1,9939 = 368
720= horizontal D-1 resolution
59/54 (x,y)= PAL pixel aspect ratio (ITU-R BT.601-4 standard, formerly known as CCIR601)
448= horiz. SVCD res without borders
480= horiz. SVCD res (2/3 D-1)
1,9939 = original aspect ratio
368= vertical SVCD res without borders
"custom size" is 448x368, target res 480x576.

You can do the calculation with FitCD. I highly recommend to read the ReadMe.




<font size=-1>[ This Message was edited by: Truman on 2002-01-14 08:41:39 ]</font>

[APVM]

Thanks very much, now I have a small problem, the file was actually 640x304 instead of 604x304 that I posted earlier, what will be the new custom size? Please help me out so that I could use this answer as an example on how to use FitCD, TIA

[APVM]

I got 448x350 if I add 2 blocks tv overscan, is this correct?

[Truman]

2 macroblocks Tv overscan is correct. As Lars17 said, TV overscan area varies from TV to TV. 2 blocks @ SVCD resolution is about 6,66% overscan, mostly the overscan area is even larger.
448x350 is not correct. The proper ratio would be 448x370, but compare the number of macroblocks.
448x370 = 4032 blocks
448x368 = 3920 blocks.
Of course you need a higher bitrate to encode the higher number of macroblocks @ same quality.
That's why I highly recommend to crop 1 pixel off the original (top or buttom) to keep the aspect ratio.
If you use CCE as encoder you have to resize to 448x366 (due to a little cce bug), that means you have to crop to 604x302 to keep the aspect ratio.
If you still use TMPG to resize, go to the advanced tab and doubleclick on "clip frame".
clip frame setting: top or buttom 1, the rest 0, do not check mask
arrange setting: center[custom size] 448x368

[APVM]

Thanks for the info, I use FitCD to calculate, if I use input file size 604*304, I can get 448*370 but if I use 640*304 (which is the acutal file resolution) I got 448*350. Please confirm same 448*368 for both 604*304 and 640*304 original file resolution. TIA

[Truman]

..oops, I did not read correctly.
You are right, resize 640x304 to 448x350.

[APVM]

Thanks, I am now ready to encode with following TMPeng settings

clip flame settings : 1 bottom, 0 top, rest 0, do not check mask

arrange settings: center[custom size] 448*348

is above correct and can you explain why I have to cut 2 off from 448*350 to 448*348, TIA

[Truman]

Well, I think I confused you a little
Since the source is 640 x304, it is a complete different calculation. No need to crop. Just set video arrange method: center [custom size] 448x350.

[APVM]

I take it that I don't need to do the clip frame top or bottom 1. Anyway this is really heavy stuff, I don't think I could make this SVCD without you, thanks again.