FFMPEG vs FFVFW vs Mencoder ?
 

Hi,

Could someone make a summary of the differences between these encoders/codecs, in the rate control area, bugs, etc.?

I'm still trying to find if any of these is reliable for KDVDs in respect to max/min bitrate enforcement. :roll:


Bilu

AFAIK there is none :-?

They all use the same encoder... libavcodec :D

That's what I thought too until reading this Kwag's post:

http://www.kvcd.net/forum/viewtopic.php?p=62465#62465
Bilu

I just know that if you wanna compile mencoder, you have to download the libavcodec folder of ffmpeg :-?

They have different rate control algorithms.

Which one is better ? :D

Bilu

My results of mencoder are in this moment much better!

(less blocks ... totally linear Q Curve, peaks wont get ofer 3000-4000kbit at 704x576/25fps)

But that could be a seetings reason ......

Rate-control related parameters in FFMPEG:
IMHO -bufsize and -bt may play a big role in VBR. Would like to know more about these.

I'd like to know a bit more about -qblur and -qcomp.
IMHO -qscale is obviously not recommended: fixed quantizers means all frames, simple or complex, are compressed with the same quantizer.
There is no way to respect a maximum bitrate if you CAN'T compress a frame enough to fit in the bitrate range because the fixed quantizer won't let you.

Example: try to fit 50% of 8 MB into 3 MB. You can't, you'd have to change from 50% from something else. That's why fixed quantizers bring no garantees!

These can't be considered documented :/

EDIT: All my doubts in this post were gone after reading Mencoder docs. Read next post :)

Bilu

Rate-control related parameters for Mencoder

http://www.mplayerhq.hu/MPlayer/rele.../man_page.html

Section CODEC SPECIFIC ENCODING OPTIONS (MENCODER ONLY)

As you see, lots of stuff is related to FFMPEG, but it's better documented :)
There is some new neat stuff as well.

The better documented stuff:

Now the neat stuff :)

Seems to me there are good reasons to choose Mencoder, particularly -vqsquish (if it works, of course ;) )

Conclusion: avoid -vqscale (to respect max/min bitrate) and use -vqsquish (if it works).

Bilu

FFVFW

Ratecontrol -> one pass CBR -> "Use continuous function to limit quantizers within qmin/qmax"

or

SQUISH.REG
========
Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\GNU\ffvfw]
"ff1_rc_squish"=dword:00000001

Seems to be the same as -vqsquish.
Is FFMPEG the only one without this feature ? :roll:

Bilu

I'd like to hear some feedback about:

FFMPEG -maxrate and -minrate being respected WITHOUT -qscale;

Mencoder -vrc_maxrate and -vrc_minrate being respected WITHOUT -vqscale;

Please post your experiences. Thanks.


Bilu

Maybe not the Feedback that you want to hear but .... interesting that mencoder seems to encode more agressive :arrow: sharper, more gibbs, etc. , FFvfw looks more easy and CCE got the best quality in underwaterscenes according to blocks.

All three samples got almost the same filesize but watch the behaviour of the Q curve! Another example the Bitrateviewers Q curve output does not say something exact according to quality, cause here does look ffvfw the best, but very near followed by CCE.

Pics are cropped an 200% Scaled, safed as Jpeg at 50% Quality

http://www.digitalfaq.com/archives/i...2004/02/35.jpg

What settings did you use?

Settings that may worth checking in Mencoder:

Bilu

Anyone willing to test these? :)

-------------------
1-pass only

-vqsquish=1 in 1-pass encodes
-------------------
Independent, may improve quality

-mbd=2
-trell
-cbp
-------------------
Complementary, one adjusts spatial detail, the other readjusts the per-MB quantizer

-scplxmask=0.5
-naq
-------------------
Complementary,SATD is slower but better than default SAD, when using SATD we should use a larger diamond setting

-precmp=2
-cmp=2
-sucmp=2

-predia=-2
-dia=-2
-------------------
Per macroblock quantizer

-mbqmin
-mbqmax
-------------------


The reason why I'm asking others to test instead of testing myself is because my Windows PIII-850 machine has burned the motherboard (not really burned, just leaking components (condensers?) that stop it from booting. For about a month I was about to boot with a stronger power source, but not enough anymore.

I'm writing this on my company's PIII-500 laptop which I need too much to be operational to risk doing experiments.

I'm considering using an old Pentium 200 with 64 MB RAM for DVD-backups: learn to use FreeBSD (it's very fast), install Mencoder, learn to script and create a set-and-forget DVD5-DVD9 tool for my own use. It'll take time, of course, but it would be a good use for that machine ;)

I also want the Windows machine (when I upgrade it) to be free for other stuff. Anyway, it's just a plan: I still didn't check the hard drive limitations of that old Pentium board, may not handle the 20 GB disk I have reserved for it :)

But for that I need to know if I can make reliable DVD encodings with Mencoder, i.e. according to the specifications.
Quality would be nice too :roll:


That's why I'm digging for the best parameters for you mates to test ;)
C'mon, I know you're interested too :twisted:


Cheers,
Bilu

Hi Bilu,
You're on the right path when you ask about all the arguments like vqsquish, but the thing is I like man pages written with substance and mplayer ones just don't have it...
What should I try with vqsquish? vrc_minrate/vrc_maxrate, or vqmin/vqmax, or both and vqscale...
Damn, I'm just not sure if vqmin should have lower figure than vqmax or opposite.
I think I'm just not the guy that's going to discover how it's done.
Somebody had some more luck than myself?
Because most of my tests with these babies are giving me buffer underflows when encoding.
Cheers

@rds_correia

-----------------------------------------------
-vqscale should be abandoned for good. Why encode with a fixed quantizer? How will an encoder limit the bitrate if the quantizer is fixed?
-----------------------------------------------
Everyone (1-pass OR 2-pass) should try these, they may improve quality:

For rate distortion:
-mbd=2
-trell
-cbp

To avoid blocks, -naq is to try to maintain the per-MB quantizer average with *_mask:

-scplxmask=0.5
-naq
-----------------------------------------------
If you want to limit quantizers you should use these:

-vqmin (min quantizer)
-vqmax (max quantizer)
-mbqmin (min per-MB quantizer)
-mbqmax (max per-MB quantizer)

If doing 1-pass and limiting quantizers you can use:

-vqsquish=1
-----------------------------------------------
If you want to try better motion estimation (slower) try:

-precmp=2
-cmp=2
-sucmp=2
-predia=-2
-dia=-2
-----------------------------------------------


About your buffer overflow problem, I don't know how stable the Windows port is. :?

About documentation, I'll do my best to try to get it for you guys :)
I DO want you to test! ;)

Bilu

About the -vqcomp switch:

http://zebra.fh-weingarten.de/~maxi/.../msg00433.html
Bilu

Another interesting Mencoder switch:

-mv0

try to encode each MB with MV=<0,0> and choose the better one this has no effect if mbd=0


Translated into english :roll: this means that it will try to encode each MB as no-motion if possible. Meaning less bitrate and better quality.

Bilu

Looks like what we want is constant quantisizer, if the resulting filesize does not goes beyond the max or below the minimmum. In those cases (and only on those cases), we want the quantisizer to be shiftet up/down to respect max/min. And I don't see a way to do that using any of this options... :(
So looks like a 1-pass VBR quality based, respecting max/min is impossible with mencoder, unless some changes are made in the source code. Doesn't it?

Hi VM,
Completely agree with ou pal :D
I starting to sense that there is just no way.
It's just not the way these libavcodec based encoders were made to run.
Either you really want constant quality or average bitrate.
I am pretty sure by looking at different constant quality encodes done with q=2 and others with q=3 that, even if the encoders could switch from 2 to 3 and 3 to 2 when needed, you would actually see when it does the switch because of the big difference in the quality provided by those 2 values.
But nevertheless I think we could progress to a smooth change, like a real curve, between 2 and 3. Maybe that wouldn't be so agressive to the picture quality.
C ya

Looks like I just found a possible way (maybe?). I just downloaded the latest CVS of mplayer (which includes mencoder) and compiled under cygwin. Looks like all rate control code is in a file called ratecontrol.c . Maybe we could change it for our purposes, doesn't look so hard to understand. :D Anyone with C knowledge is invited! :D

Aha! Now you're talking VM.
What did I tell you? This guy is a genious!
I'm just sad because I don't know C. That is I don't know any language but pascal, and that was a looooong time ago...
Any volunteers?
Cheers

Yeah, but Pascal is more English, while C/C++ is Martian .. "take me to your
leader, ..'Bush?' .."

-vhelp

This function holds the key:
This finds the quantisizer for 1pass vbr for
If we add the line in blue (not originally in the code), mencoder starts encoding with fixed quantisizer 8. (of course, I did this just to test) So it's only a matter to understand how it works and use a fixed quantisizer unless predicted filesize is too big. We'll get there. :D

I found ou that if you set the parameter vqscale=x in the commandline, you will receive a linear Q curve! BUT very fast blocky pictures on dark areas at lower vqscale's like 3.
IF you set vqmin=500 and vqmax=5000 including a vbitrate=xxxx (was it that command for bitrate? Im at work now) the blocks at dark scenes are almost away BUT on the other hand blocks will appear on fast moving scenes! By this - said without determine the vqscale in the line - the Q curve isn't constant anymore BUT more adaptive to the scene contend which results in less blocks in underwater scenes. But to avoid on the other hand the blocks in moving parts, you have at least to set a vqbitrate=3000.

By this BTW I obtain an encoding-speed of 25fps (my system), means realtime including Avisynth on a 25fps 704x576 stream :arrow: even a little bit faster than CCE.

But thats all for regular DVD encodings, not KDVD to put 2-3 Moves on one DVD-R Media.

Inc.

PS: So it would be interesting to see in what quality and what vbitrate value does fit the LOTR II SpecialEdition on one DVD-R including AC3. But I don't have that special Edition on my own, so I can't test it.

I have a different opinion: you want constant quality within the bitrate limits. Constant quality can not be the same as constant quantizer if you want to respect those limits. More important than the filesize is the bitrate specification.

What seems to be difficult is having a vqsquish-like parameter for bitrate, using the best quantizer but trying to keep the frame within the bitrate boundaries. And that would mean change the quantizer on a bitrate criteria, not a filesize criteria.

EDIT: From my post above, taken from a mailing list:
Solution seems to have been found! :)

vqcomp=0 -> vrc_eq=tex^0=1 -> constant bitrate
vqcomp=1 -> vrc_eq=tex^1=tex -> constant quality

And this parameter seems to respect the bitrate, not like vqscale. Could someone test it, please?

Bilu

Sorry, but this is about the same thing I said.
No it's not. Unless you want to use 2-pass VBR. But you can't have a good One Pass VBR mode that respects some average bitrate. Because you'll see something like I said: the encoder can vary the bitrate for a while, but it will get back to the average, ruining the picture, even if the high action is still happening. You can't have good quality and completelly predictable file size in 1 Pass Quality Based, it's impossible. So you must be thinking : why you want that anyway? Because this way I can use prediction (my CCE method) and do 1 pass, what is much faster than 2-pass VBR and has a accuracy of about 3% with every encoder, enough for most people.
But CBR is always known to produce bad quality in high action scenes and wast bitrate in low action scenes... Why would anyone want that? :?

Now this is interesting. I'll test it.

I was referring to respecting minimum and maximum bitrates to be DVD compliant.

IMHO this is even more important than filesize.

Bilu

I tested... But it doesn't woked as I expected. There are many places where this did not work, but the worst example is one high motion scene that got the quantisizer 30 to achive bitrates around 600, while I specified the max 2500.
Maybe we should try some other rate control equations...

I agree with you, but I think DVD standard does not define a minimmum bitrate... Actually I never got bitrate beyond 9800 using fixed quantisizer. I guess it's more problematic if we're trying to do a KSVCD/KVCD...
I am playing with vqcomp=1 and different rate controls.

This will work:

vrc_minrate=300
vrc_maxrate=2500
vbitrate=2500
vqsquish=1
vqcomp=1
vrc_eq=tex

Unlike it seems, it won't produce 2500 CBR, but will make almost what I want, that would be use quantisizer 2 unless bitrate needed is too high. In this case, use the lowest quantisizer possible to don't go over the maximmum (2500). Seems like using maxrate equal to bitrate makes the encoder don't care about average bitrate (what we want after all)

EDIT: I just have no idea how to rise the quantisizer used when Maximum is not exceeded. I've tried mbqmin and vqmin, but looks like after some time it goes to 2 again. Also I can't use fractional values...

Hi guys,
Though not having posted anything yet I've been trying VM's last post arguments except for vqcomp=1 & vrc_eq=tex.
Didn't find a way to constrain bitrate and try maintaining quality as constant as possible...
Damn, if you find a way to this let me know :) .
Maybe the next day one German guy we all know very well has come up with a nice GUI to it too :lol:
Cheers

What I posted will work, but the final size will be unpredictable. And I don't know yet how to lower the constant-when-possible quality to have less filesize.
Also lower bitrate doesn't seem to be working, but this is easy to understand, looks like even using quantisizer 2 (tjhe lowest possible) some scenes fall below the minimmum bitrate.

@vmesquita

Maybe using vqcomp=0 (without messing with the default vrc_eq) will do the trick. After all, it will aim at constant bitrate - so if you equal the average and maximum quantizer it will try the keep at the lowest possible quantizer for that bitrate. And filesize will be more predictable because bitrate will be more constant :)

EDIT: Rewriting this post, see if this is what you want:

vrc_maxrate = vbitrate -> average will be the maximum bitrate (nice idea VM :) );
vqcomp=0 -> tries to keep as close to bitrate as possible;

Seems to me that vqcomp=1 tries to keep as close to the original quality as possible but then there is the matter of how is Mencoder perceiving quality from a frame. Mencoder may find a high-motion scene to be low quality and decrease the bitrate (that's probably what happened to VM in a earlier post).

With vqcomp=0 it will try to encode in the closest possible way to the average bitrate regardless of the perceived quality, so using vrc_maxrate = vbitrate together with vqcomp=0 serves our purposes I think :)

Really cool is the fact that it won't care about texture complexity - just fit it all into maximum bitrate! ;)

Someone willing to try? ;)

vrc_minrate=300
vrc_maxrate=2500
vbitrate=2500
vqsquish=1

vqcomp=0 OR vrc_eq=1 (if you use a vrc_eq without qComp, the vqcomp becomes irrelevant)

EDIT2: vqmin and mbqmin already default to 2, so you don't need to mess with this parameter. If a frame gets less than 2500 at quantizer 2, it won't change to quantizer 1 just to fill the avg bitrate request.

EDIT3: Since this means:

- Lowest possible quantizers;
- respected maximum bitrate;

I don't know what kind of advantages a 2-pass encoding process would bring in this case. None, I think :)

Just calc the average/maximum bitrate and you're all set!
You won't even need prediction methods :twisted:

It's like a HiQ CBR :roll:


Bilu

vqsquish=1 ?

If using vqcomp=0 and vbitrate=vrc_maxrate there is a small chance that sometimes it goes over the maximum bitrate to fit the average - it depends on how much the vrc_maxrate is respected when using vqsquish=1.

If so we have to use vqsquish=0.

vqsquish=<0,1>
specify how to keep the quantizer between qmin and qmax (pass 1/2):
0 use clipping
1 use a nice differentiable function (default)

But it may not be a problem at all.

Bilu

Does anybody know if these work?

v4mv
Allow 4 motion vectors per macroblock (slightly better quality). (default: disabled)
(is this MPEG-2 compliant?)

autoaspect
Same as the aspect option, but automatically computes aspect, taking into account all the adjust- ments (crop/expand/scale/etc.) made in the filter chain.


Bilu

bilu,

Yes, what you proposed is like a hi-quality CBR, but note, this is not what we want (or at least me). Because you still can't lower the average quality, you see? I want mencoder to keep constant quantisizer, except when this will result in bitrate higher than specified. If this constant quantisizer could be specified in fractional way, that would be solved, but minimmum quantisizer can only have integer values (it seems)... :(

v4mv, if I remember correctly, crashes if used with MPEG2 in mencoder.

Quantizer=2 -> Maximum quality
Average=Maximum -> Pull the bitrate to the maximum (quantizer to the minimum -> q=2 unless bitrate > maxrate)

In this specific case (q=2) I can't understand the difference. Can you explain a bit more?

Bilu