VCD bitrate problem

[Rambytes]

Hi,

fist of all, excuse me if my english is not very good.

So, I need to create a VCD but i really need that one fit on 1 single CD.

The problem is the size of the final result. the size of the MPEG is too big!

So, I drop the bitrate, same result... i've got the EXACT file size!

Drop again de bitrate (from 1150 to 500)

Weird but true, the same file size.

So i've test different bitrate for 1 minute exaclty... always the same file size for the 1 minute Mpeg test.

What i'm doing wrong?

the tool I use because it's give me some very good result, is TMPGenc

If someone have good setting in TMPGenc to give me.

This is some information useful for you:

- The source is a DivX, and the size is 1,380,986Kb (so 1.3G)
- it's a 88 minutes in length
- I want the target can be played in a standard home DVD player
- The setting I use to encode in MPG is with a resolution of 352x240 @ 23,976fps
- the bitrate very "bug" me

and remember, I cannot cut the mpeg in 2CD... I must fit on single 1 CD, but need quality in this CD

So, I hope someone, somewhere can help me!

(and if someone speak french, answer me in this language... otherwise, the english will be very good too)

Just give me info about my problem, solution if exist, and setting in TMPGenc that will help me.

thanks alot

[AlanCake]

Hi sorry I don't know the answer to your question. But, I have experienced the exact same problem.

You hear everyone on these forums going on about 'its all in the bitrate - lower the bitrate to make the file sizes smaller' - its simply not true. There seems to be a point at which lowering the bitrate much below, I think about 1100 Kb, makes no difference to the output file size.

My theory, correct me if I'm wrong, is that the 352 x 288 pixel size requires a size of its own de facto, and therefore altering the bitrate cannot reduce that size. The only way I think you could do it is reducing the pixels.

Alan

[Baldrick]

just change in tmpgenc under settings->system to mpeg1 videocd non standard, because you are creating xvcd ...full guide here http://www.vcdhelp.com/tmpgencxvcd.htm

[wildcatfan]

Sounds like it is padding the bitrate since by spec VCD is exacty 1150 kbps vid, 224 kbps audio.

[kinneera]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
My theory, correct me if I'm wrong, is that the 352 x 288 pixel size requires a size of its own de facto, and therefore altering the bitrate cannot reduce that size. The only way I think you could do it is reducing the pixels.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

If you segment 352x288 into its MPEG 16x16 blocks, you get 396 blocks. Supposing the minimum amount of data that could be used to distinguish one block from another is 1 bit (0 or 1, monochrome blocks), you would have 396*2*25=19800 bits per second, which is about 20Kbps. A single bit is something of a logical exaggeration, but I think the minimum bitrate can go quite low, so I would go with the padding theory.