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-   -   Bitrates: Cqmatic for smartphone encoding? (http://www.digitalfaq.com/archives/encode/6965-bitrates-cqmatic-smartphone.html)

Encoder Master 12-04-2003 03:10 PM

@kwag



For me "1-77-0-1-0" gives the best compression and also good results.

Some questions by encoding at a very low resolution like 240x160:

Recommended CQ_VBR? Right, or?
Is it OK that I use a min Bitrate of 0 or should I use 1 and enable padding not to be lower than minimum bitrate?

Kwag you say 300kbps at Max; also with this resolution (240x160)?

Is it ok that I don't use b-Frames in GOP also with normal KVCD?

The Values of CQ_VBR is over 50 CQs lower than CQ is its right or better say OK?

magnus 12-04-2003 03:32 PM

Kwag

OK I lied about that being my last question. In your template you have the gop set to 1-18-3-1-48. What changes would you make? Just bump the 48 to 64 or what? You would possibly drop the framerate to 12fps? You also have all the "special settings" checked including soften block noise. Should I leave these the same.

Thanks
Magnus

Encoder Master 12-04-2003 03:46 PM

Quote:

gop set to 1-18-3-1-48
8O I can't believe that this is in the Templates or it's a good quality gop.

kwag 12-04-2003 05:06 PM

Quote:

Originally Posted by Encoder Master
@kwag



For me "1-77-0-1-0" gives the best compression and also good results.

Some questions by encoding at a very low resolution like 240x160:

Recommended CQ_VBR? Right, or?

CQ_VBR
Quote:

Is it OK that I use a min Bitrate of 0 or should I use 1 and enable padding not to be lower than minimum bitrate?
Use 0, because you'll be playing in a software player. So no need to use a higher MIN value.
Quote:


Kwag you say 300kbps at Max; also with this resolution (240x160)?
I think 300 is the MAX I would use. Just to cover high action scenes.
Quote:


Is it ok that I don't use b-Frames in GOP also with normal KVCD?
NO :!:
Without B frames, you'll get less compression.
Quote:


The Values of CQ_VBR is over 50 CQs lower than CQ is its right or better say OK?
The CQ_VBR scale is lower than CQ. So you'll get very low values.

-kwag

kwag 12-04-2003 05:46 PM

Quote:

Originally Posted by magnus
Kwag

OK I lied about that being my last question. In your template you have the gop set to 1-18-3-1-48.

Those values were in the very old templates, right :lol:
Quote:

What changes would you make?
1-5823-2-1-72 ;)
Quote:

Just bump the 48 to 64 or what? You would possibly drop the framerate to 12fps?
Try it :!:
In such a small screen, you might just tolerate the small jerkiness, at the cost of smaller final file size ;)
Quote:

You also have all the "special settings" checked including soften block noise. Should I leave these the same.
NO :!:
Clear that. Remove the "Soften Blocks". It will actually make your encode more blocky.

Also, don't use overscan blocks for that encode, because there is no overscan on those Smartphone screens. Just like in a computer monitor. Only TV's have overscan ;)

Just for kicks, here's a clip at 160x120 (QQVGA resolution).
http://www.kvcd.net/smartphone-160x120.mpg
It's 38 seconds long, and only 431KB :lol:
Please, use Vdub to play it, so that it displays in actual size. That was encoded at a CQ_VBR value of 18.59 at a frame rate of 12fps, which yields a final size of ~80MB (full video encode, without audio) :mrgreen:
You'll probably need glasses to watch it on a smartphone screen, but at that size, it looks pretty damn good :lol:
MIN was 0 and MAX was 300Kbps and GOP of 1-5823-2-1-72.

-kwag

magnus 12-04-2003 06:03 PM

Kwag

Thanks for all the help! I think that covers it. I'll be be watching quality (yet tiny) movies on those boring flights on who would have thought it.... my phone.

Thanks
Magnus

Encoder Master 12-05-2003 10:20 AM

Quote:

Quote:


Is it ok that I don't use b-Frames in GOP also with normal KVCD?
NO
Without B frames, you'll get less compression.
That's not right kwag. I've tested a lot and if you choose a GOP like "1-77-0-1-0" Than you have the best compression with KVCD Notch Matrix. Eith only one B-frame my testfile of 10minutes will be 200kb greater.

mistermickster 12-05-2003 10:32 AM

Quote:

Originally Posted by kwag
Just for kicks, here's a clip at 160x120 (QQVGA resolution).
http://www.kvcd.net/smartphone-160x120.mpg
It's 38 seconds long, and only 431KB :lol:

That clip's quite dark, I'd be interested in seeing one a bit brighter :D

Oh yeh, and how about some sound :lol:

kwag 12-05-2003 11:24 AM

Quote:

Originally Posted by Encoder Master
I've tested a lot and if you choose a GOP like "1-77-0-1-0" Than you have the best compression with KVCD Notch Matrix. Eith only one B-frame my testfile of 10minutes will be 200kb greater.

You have three types of compression:
(1) I frames only ( worse compression )
(2) I and P ( better compression )
(3) I, B and P ( Best compression )

So the lower the bitrate, #3 will give best quality.
However, for studio broadcast quality, I frames only at a very high bitrate ( ~50,000 ) will give the best quality.

I can't see how you possibly got better quality without B frames. Unless you used a much higher bitrate with I and P than with I, B and P frames.

-kwag

Encoder Master 12-05-2003 12:33 PM

Later I will post you some results and you can see what I mean. :D

kwag 12-05-2003 08:21 PM

Quote:

Originally Posted by mistermickster
Quote:

Originally Posted by kwag
Just for kicks, here's a clip at 160x120 (QQVGA resolution).
http://www.kvcd.net/smartphone-160x120.mpg
It's 38 seconds long, and only 431KB :lol:

That clip's quite dark, I'd be interested in seeing one a bit brighter :D

How about this one :D (No audio!)
http://www.kvcd.net/bourne-small.mpg

Edit: 160x120. GOP = 96 8O, 23.976fps. 3 B frames. CQ_VBR=18.59, KVCD Notch matrix.

-kwag

mistermickster 12-08-2003 06:59 AM

Quote:

Originally Posted by kwag
Quote:

Originally Posted by mistermickster
Quote:

Originally Posted by kwag
Just for kicks, here's a clip at 160x120 (QQVGA resolution).
http://www.kvcd.net/smartphone-160x120.mpg
It's 38 seconds long, and only 431KB :lol:

That clip's quite dark, I'd be interested in seeing one a bit brighter :D

How about this one :D (No audio!)
http://www.kvcd.net/bourne-small.mpg

Edit: 160x120. GOP = 96 8O, 23.976fps. 3 B frames. CQ_VBR=18.59, KVCD Notch matrix.

-kwag

That looks fine Kwag. :)

I've got to get me a Smartphone :D

kwag 12-08-2003 09:44 AM

Quote:

Originally Posted by mistermickster

I've got to get me a Smartphone :D

Me too :lol:

-kwag


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