Hi !

I tried to find answer here to my question with no success, so please
forgive me if someone asked this before:

There is any difference between CQ, VBR, 2pVBR in the case of
SVCD if I use the CBR method buth with the maximum possible bitrate
(2520) ?

Theoretically there is no difference, because if i select for example CQ
and 100% quality, i think the encoder will use the maximum available
bitrate which is 2520 and this is equal with CBR 2520. Or I am wrong ???

Please help me to better understand this process.

Thanx a lot.

In terms of mpeg2 quality there's a big difference between the CQ setting and a two-pass.

I first tried this encoder with footage from a digital video (DV) camera; I naturaly chose two-pass, since I assumed this would give me the best results. I spent a while going through the settings, to optimise the picture quality, and hit "start". When I played back the encoded vid I was dissapointed to say the least: there were quite visible macroblocks, and the picture looked generally washed out. I was going to give up on TMP, but then spotted the CQ setting. "Constant Quality", I thought "this should be interesting". Anyway I set the encoder off again having chosen a CQ of 80% and max bitrate (for DVD) of 8MB/s. This time, when I played the encoded vid I was very happy indeed. The resultant mpeg was very close in quality to the origional, a little smoother perhaps - but smooting is part and parcel of mpeg encoding - and the colours seemed a little more vivid - not over saturated - just a little it more vivid.

I now use TMP to transcode mpeg2's produced from a digital tv card to DVD compliant mpeg2. I use CQ=100% and max bitrate 8MB/s, and motion search set to highest.

The results on my DVD player are some of the best TV images I've ever seen.

Setting a max bitrate in CQ of 2520 is not the same as having a constant bitrate of 2520. With a CQ of 2520, the encoder will only use this bitrate if it necessary, eg during motion within a scene, or water or smoke effects. Having a constant bitrate of 2520 would be much less efficient, since you would be using this bitrate all the time which would require a lot more disk space (more CD's), but still end up with the same overall quality as the CQ encode.

Griff

Thanks for the explanation.

So, if we did not talk about the size issue, then
the (CQ 100% 2520) and (CBR 2520) will produce the same
quality output .?

The reason why I am not checking the size is I would like to
make a 2x80min cd svcd from and 1hr20mins source, and this
is perfectly fit to the 2 cd even with the 2520 constant bitrate.

If you're happy twith the resultant quality then go ahead. However, you would be able to use a higher CQ setting for those 2 CD's. The problem would be that you wouldn't know the final file sizes, 'till the encoding had been completed.

Griff