FFmpeg: GOP of 25 Seems to Eliminate Noise?

[Razorblade2000]

Wow... Just love ffmpeg! It is soooooooooooooooooooooooo fast!!!

ATM I am trying to encode some Family guy eps I captured from TV (mpeg4) to KVCD LBR (avg bitrate 550)

Using your ?KVCDx3? Params it looked really fine!
Having ULBR Bitrate makes the blocks round the MOVING edges really much
Also after scene changes there is a really horrible picture (1 sec later everything is fine again)

btw:
if he REALLY compresses audio in 64 kbit/s (like i told him) it sounds pretty damn good!!!!

edit:
A lot of rc buffer underflow over here... (guess it's the long gop and the low bitrate?)

my command line:

ffmpeg -hq -i '/windows/H/Cartoonconvert/Family Guy - s1 Ep14 - The King Is Dead.avi' -ar 44100 -acodec mp2 -ab 64 -ac 1 -minrate 64 -maxrate 900 -b 575 -bt 50 -qmin 6 -qmax 25 -g 25 -i_qfactor .1 '/windows/E/Test.mpg'

SOMEHOW a GOP of 25 seems to eliminate much of the stuff around moing edges!

[kwag]

Hi Razorblade,

Increase your GOP to at least 12 ( -g 12 )
Try this:

ffmpeg -i '/windows/H/Cartoonccaptures/Family Guy  -s 352x240  -minrate 64 -maxrate 900 -qmin 5 -qmax 25  -g 12 -bufsize 320 '/windows/E/Test.mpg'mpg

See how it looks now, after scene changes.
Look at the average bitrate while encoding. If it shows above your wanted of 550, then increase the qmin.

Ignore the underruns, and demux your stream with TMPEG, and remux with BBMPEG ( as we usually do ).
I'm trying a couple of clips in my standalone in a while.

-kwag

[kwag]

I guess you edited your post while I was posting

-kwag

[Razorblade2000]

I edit my posts all 5 minutes! Playing with ffmpeg is fun

btw. what was bad about long gops again? do they cause playback problems on dvd players? (because the longe the gop, the better the video looks @ me!)


EDIT:
the avg bitrate he shows is video+audio (afaik see) ?!

EDIT2:
How about 2 Pass with ffmpeg?

Edit3:
I could also have my video filtered in windows (avisynth) and saved in huffyuv format...

Edit4:
Still can't belive how FAST ffmpeg is... prediction will be more accurate when your/our ffmpeg kvcd work as we can take bigger samples (it's fast anyway)

[kwag]

Can't mux correctly
No matter how I encode, and demux with TMPEG and remux with BBMpeg, TMPEG or Mplex, the muxed mpeg is useless
Too many video DTC underflow errors, and just doesn't play correctly on my DVD players. On the PC, it works fine.
I guess we have to wait more time ( which I hope is not too long, as ffmpeg project was registered on 2000-12-06, so it's been almost 3 years since the project started )
If someone can shine a light on this, and is able to correctly mux a ffmpeg created mpeg file ( at least as VCD 352x240 ), please let us know
I can't even create a CBR stream
Everything comes out VBR, no matter how I set -qmin, -qmax, -b, etc.

-kwag

[Razorblade2000]

hmmmm... i got it working without more than 3 or 4 under and overflows!!!
Now I just have to remember my commandline


I'll reboot linux in a minute

[major4]

Quote:

Originally Posted by kwag

Can't mux correctly
No matter how I encode, and demux with TMPEG and remux with BBMpeg, TMPEG or Mplex, the muxed mpeg is useless

Exactly.. that's the problem with ffmpeg, there is some monster bug in the muxer. Be sure to use -f vcd however, in order to set the correct block size.

Quote:

Originally Posted by kwag

I can't even create a CBR stream
Everything comes out VBR, no matter how I set -qmin, -qmax, -b, etc.

Yes, that's another bad point, as this chokes many DVD players expecting mpeg-1 to be CBR as per VCD specs.

[Razorblade2000]

Seems as if I encoded with these params:

Quote:

ffmpeg -i '/windows/H/Cartoonconvert/Family Guy - s1 Ep14 - The King Is Dead.avi' -minrate 96 -maxrate 1250 -qmin 5 -qmax 25 -hq -g 12 -b 600 -bufsize 320 -bf 2 -acodec mp2 -ab 64 -ac 1 '/windows/E/Test.mpg'

Now I am having fun with this:

Quote:

ffmpeg -i '/windows/F/Testingit.avi' -s 352x288 -hq -qmin 6 -qmax 25 -r 23.976 -bufsize 320 -aspect 4:3 -g 18 -f vcd -sameq -b 1050 -ar 44100 -ac 2 -ab 112 -i_qfactor .1 '/windows/E/Testingit.mpg'

the 1st one gave very few flows as far as i remember...
the 2nd one gives me no flows...
(doesn't -sameq profit from the work of the xvid/divx codec?! The bitrate-distribution should be according to the 2 pass encoded avi file? or am i getting this wrong?!)

[Razorblade2000]

BOTH of the files WORK IN MY STANDALONE!!!

The Family guy episode was muxed with tmpgenc (non-standard vcd) and the Testingit avi was muxxed using bbmpeg (kvcd params from the forum!)

As the testingit.avi wasn't 4:3 as the family guy episode it looked pretty weird stretched...

ssssssssssssssssstrike!

[kwag]

Hi Razorblade,

Thanks for the test
I think I now zeroed in on the problem.
It a problem with the quantisizer and the minimum ( -qmin) value.
If you set it lower that 3, you get errors. So this is the command line I'm testing now, and it's working correctly without any errors!:

./ffmpeg -i ~karl/sample.vob -s 352x240 -hq  -r 23.976  -g 24 -b 1150 -ar 44100 -ab 112  -qmin 3  ~karl/test.mpg

I stretched the GOP to 24 (-g 24), just to see if it worked, and it does. But I suggest 18, because of the lack of B frames.

Here's a sample, demuxed with TMPEG and remuxed with MPlex as non-standard VCD (VBR) just like with BBMpeg, and plays flawlessly on my DVD players:

http://www.kvcd.net/downloads/ffmpeg...red-planet.mpg

It does look a little on the green side ( encoded directly from a VOB ). Will have check on that later on. The thing is, that now it does create a correct compliant stream
There are "ZERO" errors when remuxing.
I burned it with VCDEasy, with MPEG compliance checks, and there were no errors reported at all

-kwag

[Razorblade2000]

Great...
does this commandline produce vbr? When it doesn't give you a good cq mode (for me it looks more like some kind of abr?!), you could also try "-pass 2"... works fine 4 me as ffmpeg is sooooo fast

How do you get your Aspect Ratio right (I guess it's because u used .vob files, avis screw this pretty much up... guess I'll have to rip some DVDs (which seems to be illigal in germany by now )

btw:
try reducing your audio bitrate! The family guy episode I did was @ 64 kbit/s and sounded very good to me!!!

[japie]

Quote:

Originally Posted by Razorblade2000

How do you get your Aspect Ratio right

-aspect 1.7777

Quote:

Originally Posted by Razorblade2000

try reducing your audio bitrate! The family guy episode I did was @ 64 kbit/s and sounded very good to me!!!

I have bad experience with lowered bitrates for audio on different hardwareplayers, everything lower than 128 will unsync things. (well I didn't test 112

[Razorblade2000]

H3h3... as my player plays nearly everything... 64 kbit/s works fine for me...

[japie]

Mine plays everything I feed im too, only I have some friends who wanted a "brand" (sony) and they give problems, they play them only sound will go out of sync after a while.
No problems on my cyberhome or philips doo.

[japie]

Quote:

Originally Posted by kwag

./ffmpeg -i ~karl/sample.vob -s 352x240 -hq  -r 23.976  -g 24 -b 1150 -ar 44100 -ab 112  -qmin 3  ~karl/test.mpg

I tryed it too on; http://download.divx.com/showcase/HomeWorld1024.avi with the following line:

ffmpeg -i Unzipped/test_video/divx.avi -s 352x240 -r 23.976 -hq -g 24 -b 1150 -ar 44100 -ab 112 -qmin 3 test.mpg

and vcdimager gave me:
packet length beyond buffer (pos = 2054 + size = 2042 > buflen = 2324) -- stream may be truncated or packet length > 2324 bytes!

Burning your file worked fine do.

[kwag]

Quote:

Originally Posted by japie

and vcdimager gave me:
packet length beyond buffer (pos = 2054 + size = 2042 > buflen = 2324) -- stream may be truncated or packet length > 2324 bytes!

Did you demux with TMPEG, and remux with BBMpeg

-kwag

[japie]

Quote:

Originally Posted by kwag

Did you demux with TMPEG, and remux with BBMpeg

So I did:

ffmpeg -i $1 -s 352x244 -r 25 -hq -g 18 -b 1150 -an -qmin 3 -f mpeg1video test.m1v & ffmpeg -i $1 -r 25 -ab 112 -ar 44100 test.mp2 & tcmplex -i test.m1v -p test.mp2 -o test.mpg -m b

And I'am watching it now!
Pitty the buildin multiplexer breaks the mpeg. Can't we make a bug/wish list for the ffmpeg people?

[major4]

Japie, if you use -f vcd without remuxing, does it work?

[kwag]

Hi major,

I did try the "-vcd" option, but the video jumps and skips on my standalone.
But the same mpeg, demuxed with tmpeg and remuxed with bbmpeg, plays correctly.

-kwag

[major4]

And if remuxed with mjpegtools mplex does it play as well?