which method to use to make a prediction with tmpgenc xpress? in CQ

Hi tamahome,

We can't use CQMatic with TMPEG xpress, to predict CQ
They changed a lot of options on TMPEG.

-kwag

What about using the CQ predicted with TMPG 2.5x in TMPG XPress?
Will it produce a file with approximately the same size or is it totally off?

Hi muaddib,

No it won't.
I believe Fabrice tested just that, and he got different file sizes with the same CQ on both encoders.

-kwag

Ok kwag, thanks ... I was suspecting that.

Hi,

I don't have the test here, but it gave me a very big difference: they change their CQ function (It seems it compress a bit more), and there is a big difference between both CQ.

I'm just using Ping-Pong Method, and it gives me great (manual) results...

Salu2
Fabrice

Hi fabrice,

By saying that you mean that you have to use a higher CQ to achieve the same size?
What about the difference of the CQs... (approximately) how much do you have to increase it to get the same size?
Is this difference constant?

Thanks!

Hi Muaddib,

If I remeber well, yes. You can do yourself the test, using the trial version.

Well, I have to do some test, but right now, I don't remember...
I'll try to encode in mpeg1 with the 2 version, with the same CQ, and post here the differences...

Salu2
Fabrice

Ok fabrice, thanks!
I will make some tests...

Hi,

Here are some test I did with a sample generated by Inc slicer's function, in mpeg1 (to be able to compare the same settings):
- Tmpgenc 2.521 CQ 70 = 34508 Mb
- Tmpgenc xpress CQ 70 = 31885 Mb
- Tmpgenc xpress CQ 71,3 = 34507 Mb

As the size/cq chart is not linear, I think the diff. can not be linear, but let's see it...

Salu2
Fabrice

What about the quality?
Did you catch any difference?

i have tested in mpeg 2 it's very different

tmpgenc 2.521 1h51----->CQ 75-----> 1190mb
tmpgenc xpress 1h51---->CQ 75 ----> 728mb

0_0 quality mpeg 2 it's better and fast in tmpgenc xpress (in processor p4)

Hi tamahome.

Do you mean that the file of 728mb looks better than the one 1190mb
That's quite a file size difference, and I don't know how the 728MB can look better

-kwag

I was surprised yes in spite of the difference in size quality is identical to see better (the video stays a concert live one see block effects easily with the lights thing who less often returns with xpress)

I speak in MPEG 2, I do not make a MPEG 1

and a same size tmpgenc xpress is CQ87 for Cq75 in tmpgenc 2

Hi,

SSIM values are:
- tmpgenc 2.521 = 78.62
- tmpgenc xpress, CQ 70 = 78.33
- tmpgenc xpress, CQ 71,3 = 78.81

So no real difference.

From visual test, I don't really see differences (it was expected with so near SSIM value). I can post somewhere the samples: 30 Mb each...

Salu2
Fabrice