Question concerning AQ at High Quality Bitrate and Anamorphic Encoding [Archive]

Splashdriver

6th July 2004, 18:46

Thanks...I guess enabling GMC is the best thing to do for this movie since I've spotted quite a lot of panning and zooming and stuff.

I normally don't encode movies with such a high bitrate, but this movie is 13h_12 min_47 sec ...[edit]oops....it's more like 3h_12 min_47 sec[edit]... long, so I was thinking that this movie would definitly need more bitrate (and a bigger file-size ofcourse) just to achieve good quality (I use the 'Didees SixofNine' matrix, guess that should improve things even more ;) ).

Gordianknot gives me a 76% compressibility test result (I believe AQ wasn't enabled in the codec settings, b-frames were at default). Lowering b-vops to 1/1.50/1 might be useful, but I'm not sure on that on.

@Teegedeck:
When encoding anamorphically (no resizing,just cropping)and setting the aspect ratio in mmg to 2.35.1 I end up with a 986x420 resolution movie. Would it be better to use AQ in this case since the resolution has become bigger in width or am I talking complete non-sense here:confused: ?? (source is DVD Pal btw)

sorry for repeatedly asking questions, but sometimes searching the forum just isn't enough..hope you 'll understand.

thanks in advance,
Splashdriver

Teegedeck

6th July 2004, 19:28

Bitrate, resolution, frames per second and duration are all factors that come into play. Compressibility is a good indicator for what you should use. Using high-bitrate matrices gives the most perceptible difference of all options. But with SixOfNine you already use one of the top-notch matrices.

Lowering B-vops probably won't get you far if you want better quality.
Edit: Sorry, I wasn't reading thoroughly at first.

loni_blues

6th July 2004, 19:56

Hi,
Adaptive quantisation gives more benefit for real bitrate constraints, now you're giving the codec enough space to do it's magic without the AQ trade-off.
What would be a recommended bitrate for using AQ?
Thanks,
loni_blues

Koepi

6th July 2004, 20:27

It's not just about bitrate, it's about the movie content itself as well. An underwater movie would most likely suffer from AQ.

I'd recommend using AQ at bitrates below 800-900kbps at 640x272 resolution - but that isn't a qualified value, it's just plain right out of my guts.

Regards
Koepi

Teegedeck

6th July 2004, 20:31

There is no magical figure for that.

It comes down to taste and to the individual movie. It has been shown that AQ can be a bad choice for scenes with darkish-blue backgrounds. That's the only real 'problem sample' we have encountered till now.

Apart from that: If your encode is all q=2 without AQ, then you definitely don't need it. :p But already a bit below that you actually have a difficult choice to make: Do you prefer p-frames constantly fluctuating between q=2 and q=3 or do you prefer having mostly q=2 (but most probably also some q=3) with some MBs in them quantized at q=3 or q=4? I think some frames are bound to look better, some are bound to look worse, it's hard to make a quantitative or even qualitative assessment about the benefits. I go for AQ but that's just me (well, not only me in fact, which is quite reassuring) and I'm mad as a march-hare. :rolleyes:

Splashdriver

6th July 2004, 22:07

@Teegedeck:

I've been lurking for quite a while and if I remember correctly you've done many HQ anamorphic DVD rips (right?) with AQ enabled. Now Koepi's opinion on AQ is to use it on "bitrates below 800-900kbps at 640x272 resolution , although it "isn't a qualified value". Is it safe to conclude that you don't fully support this statement and may I ask why?

Thanks in regard,
Splashdriver

Teegedeck

6th July 2004, 22:31

Excuse me, but which part of "it comes down to taste and to the individual movie" is unclear? At least I haven't made enough tests to help you on this one. I merely stated that I'd go even further than Koepi in saying I can give absolutely no 'do' or 'don't' on this one. I have no proof for a superiority of my personal preference using AQ.

Splashdriver

6th July 2004, 23:28

sorry, I shouldn't have been so stubborn when feeling sleepy:p
yes, you're right..guess I totally missed that part. I'm on a PIII 1ghz, so I'll have to wait quite a few hours to check the final result of the 2nd pass. (should be good quality to back-up though). We'll see :D

lexor

7th July 2004, 01:08

Originally posted by Splashdriver
...but this movie is 13h_12 min_47 sec

13 HOURS? what version do you have? the long promissed Extended (on steroids) version? Thatrical release is only 3 hours, your DVD is 4 times bigger!:eek:

Teegedeck

7th July 2004, 06:49

I regarded it a typo. The bitrate mentioned points to that.

Splashdriver

7th July 2004, 06:52

Stupid typo;)
It should be 3h_12 min_47 sec ofcourse...maybe when they start developing triple-layer DVD-burners and discs one day I'll will get my 13 hours of real DVD quality :D

Lagoon

7th July 2004, 21:05

"@Teegedeck:
When encoding anamorphically (no resizing,just cropping)and setting the aspect ratio in mmg to 2.35.1 I end up with a 986x420 resolution movie."

Something's wrong here, this is NOT anamoprhic but just plain square pixels.

Anamorphic would be 720x420.

Teegedeck

7th July 2004, 21:13

Right. It's not anamorphic but a true 16:9 frame.

SeeMoreDigital

7th July 2004, 21:41

Originally posted by Lagoon
Something's wrong here, this is NOT anamoprhic but just plain square pixels.

Anamorphic would be 720x420. Yep, something is indeed wrong!

When generating anamorphically cropped encodes from DVD sources where the original movies AR is 2.35:1. For NTSC, try using 368 vertical pixels and for PAL, try using 432 vertical pixels.

Cheers

loni_blues

8th July 2004, 03:27

@ Koepi & Teegedeck,
Thanks for the advice!
Regards,
loni_blues

Splashdriver

8th July 2004, 03:50

Seems I got this thing completely wrong overall....:(

Used GKnot for (auto-)cropping the source.....it gave me a resolution of 720x420.....W/H Module=16), since I didn't resize at all I assumed it was equal to anamorphic encoding.
Hitting the Smart Crop left-Right does give me an output of 720x432 in GKnot where the aspect ratio box says 1.667 with 0.0 aspect error. Now is this the thing that you guys are talking about? (sorry for asking real stupid questions, but I'm just really eager to learn)

I'm afraid I've probably wasted 2 long days of stupid encoding:(

SeeMoreDigital

8th July 2004, 09:48

Originally posted by Splashdriver
Hitting the Smart Crop left-Right does give me an output of 720x432 in GKnot where the aspect ratio box says 1.667 with 0.0 aspect error. Now is this the thing that you guys are talking about? (sorry for asking real stupid questions, but I'm just really eager to learn)

I'm afraid I've probably wasted 2 long days of stupid encoding:( First I have to ask.. do you know what anamorphic encoding is because the concept can be difficult to grasp and some explanations are often difficult to understand?

Anyway, with Mpeg2/DVD anamorphic images the 'height pixels' (480 for NTSC and 576 for PAL) have a static shape ie: they are not allowed to stretch or squash but the 'width pixels' (720 for both NTSC and PAL) have a distorted shaped ie: they are allowed to stretch or squash.

However, pixels like being encoded square (in much the same way dots like being round) so if you want them to change shape ie: make them become rectangular, you have to tell them. And this is where the expression PAR (Pixel Aspect Ratio) comes in.

With the XviD codec you will find many PAR values you can set. And once selected, the value will be embedded within the video stream as a signalling code, which in-turn will 'hopefully' be detected and decoded by your media player/direct-show filter.... hopefully!

As I don't use GK so I'm not familiar with the terminologies and expressions they use. However "when you do the math" 720 divided 432 does equal 1.666, so it looks like GK has given you the aspect ratio of the image pixel frame size... which is correct for square pixels.

All you've got to make sure of now is... did you remember to give the pixels a PAR shape?

If you did, then your in business. So all you've got to do now is find a media player (or configure a media player) so that will display your anamorphic encodes correctly. If you're not sure "Don't Panic" because there's a wonderful little tool called MPEG4modifier (http://forum.doom9.org/showthread.php?s=&threadid=78050), that can do this for you now!

Cheers

Splashdriver

8th July 2004, 10:28

Guess I'm a complete dumb-ass on the subject. I was told that encoding anamorphically results in a much bigger width and when using the appropriate player it correctly displays the image on resize (sorry If I'm not so techie on the explaining). Guess I still have a LOT of reading up to do (but that's ok, I like to learn:D )

In the Xvid codec I selected the following:
Pixel Aspect Ratio - select the shape of a pixel...: 16:9 PAL

I guess something is still wrong here since I didn't select 720x432 as my resolution but 720x420 (which is true 16:9 frame as been said). I'll will have a look at MPEG4modifier as soon as possible.

seems like MPEG4modifier doesn't support MKV, which is my favourite container for quite a while now)

PS: I always use Media Player Classic to playback movies and stuff.

SeeMoreDigital

8th July 2004, 11:16

Originally posted by Splashdriver
I guess something is still wrong here since I didn't select 720x432 as my resolution but 720x420 (which is true 16:9 frame as been said). True, 720/420 = 1.71:1 (which is nearly 1.77:1 aka 16:9) but anamorphic encoding does not work like this....

Anamorphic encoding is all about PAR. Which in this case is designed to stretch the width shape (ie: along the 720 axis) of pixels to fill an imaginary 1024 pixel shape (and 1024/432 = 2.37:1 which is as near as damn 2.35:1).

And the reason why 1024 is the imaginary shape to aim for is because 1024/576 = 1.77:1 which is 16:9PAL (which is what you would use if you wanted to generate encodes using square pixels and not anamorphic pixels).

Originally posted by Splashdriver
seems like MPEG4modifier doesn't support MKV, which is my favourite container for quite a while now).... PS: I always use Media Player Classic to playback movies and stuff. I'm an MP4 container fan myself and I'm happy to report that MPC will play anamorphic encodes perfectly as long as you have the necessary DSdec filters installed.

Anyway, here's a download link for 2No short anamorphic test files I've generated for you to try (http://homepage.ntlworld.com/seemoredigital/PAR_crop_tests.zip). They were both encoded using XviD. One is in the .AVI container, the other is in the .MP4 container.

Good luck

Cheers

EDIT: A bit more anamorphic info added

Splashdriver

8th July 2004, 12:00

True, 720/420 = 1.71:1 (which is nearly 1.77:1 aka 16:9) but anamorphic encoding does not work like this.... anamorphic encoding is all about PAR. Which in this case will stretch the shape of the (720 axis) width pixels to fill an imaginary 1024 pixel shape (and 1024/432 = 2.37:1 which is as near as damn 2.35:1).

Actually mmg outputs a 1046x420 resolution when no aspect ratio is selected (input resolution was 720x420). Now, since I wish to do a anamorphically encode, does this mean that I have to do both passes all over again (but this time 720x432 as resolution)??

When selecting an 720x420 file as input in mmg and setting the Aspect Ratio to 2.35.1 it gave me 986x420 file. Though I've been told that that's absolutely not anamorphic it doesn't look distorted at all (to me). It actually even tends to look a bit sharper, don't ask me why.

Thanks for the short files SeeMoreDigital, I'll definitely keep the mp4 file (both have nice quality man!). I did notice one thing. MPC (6.4.8.2) crashes when I try to acces play-> filters. Don't know why, the Avi file doesn't seem to have this problem, since I could acces the FFDshow(29-05-2004) property window with it.
Seems like enabling/disabling Hardware Overlay Mixer in FFDshow doesn't have any effect on resizing.

[edit] How do I change the name of thread (if that's possible)???

SeeMoreDigital

8th July 2004, 12:50

Originally posted by Splashdriver
[edit] How do I change the name of thread (if that's possible)??? Go to your first post, press the edit button and re-enter the 'Post subject'.

Originally posted by Splashdriver
Thanks for the short files SeeMoreDigital, I'll definitely keep the mp4 file (both have nice quality man!). I did notice one thing. MPC (6.4.8.2) crashes when I try to acces play-> filters. Don't know why, the Avi file doesn't seem to have this problem, since I could acces the FFDshow(29-05-2004) property window with it.
Seems like enabling/disabling Hardware Overlay Mixer in FFDshow doesn't have any effect on resizing. I would recommend that you install the latest 3ivX codec, which comes with the correct type of decoder filter, suitable for playing anamorphic Mpeg4 in .MP4.

Cheers

Splashdriver

8th July 2004, 17:45

Name of the post-subject has been changed from now

Stux

10th July 2004, 06:39

Encoding anamorphically is simple.

You crop off the excess image (say black bars), then encode with the right PAR preset.

There's no step 3 ;)

You don't actually have to worry about what actual size you end up encoding, just crop what you need to... perhaps crop a bit more to get the image to multiples of 8, then just encode with the right PAR preset.

Splashdriver

10th July 2004, 07:10

Originally posted by Stux
Encoding anamorphically is simple.

You crop off the excess image (say black bars), then encode with the right PAR preset.

There's no step 3 ;)

You don't actually have to worry about what actual size you end up encoding, just crop what you need to... perhaps crop a bit more to get the image to multiples of 8, then just encode with the right PAR preset.

I remember I read that somewhere (Sorry, can't remember where I read that thing exactly). Assuming I had the right information, I went to Gknot and just cropped of the black bars in the image, ending up with a resolution of 720x420. After that I commented out the resize thing in Avisynth. In the Xvid codec I made sure I set PAR to 16:9. I'm a bit confused here, because I don't think Teegedeck and SeeMoreDigital where saying the same thing that you just said Stux. I definitely need some more light to be shed here.

Thanks

SeeMoreDigital

10th July 2004, 10:57

Splashdriver

Try testing these Mpeg4 PAR 720x432 anamorphic test (http://homepage.ntlworld.com/seemoredigital/PAR_crop_tests.zip) files in both the AVI and MP4 container.

It might help you know what you've got to aim for!

Cheers

D-wizzz

10th July 2004, 13:11

hi.
@ see more,

Your explanations on anamorph encode is very helpfull. i've been reading up on that subject to for a while now.i also like it that it's in a language even i can understand with out getting lost a sea of terms and words.i've seen your test files btw and they look awesome,just out of curiosity which xvid stettings did you use to create those files.

Bye:D

SeeMoreDigital

10th July 2004, 13:28

Thanks D-wizzz,

Don't get too excited, the encode only looks as good as it does because there's very little pixel movement in it.

I reckon your Avatar contains more movement than my encode!

That said, there's nothing special about the settings. It just used XviD's defaults with B-VOP disabled and AS @ L3 Profile selected (not that this is really necessary). Under the 'Aspect Ratio' tab a PAR setting of 16:9PAL was used. And a 2pass VBR encode was generated.

And thanks for confirming that my anamorphic explanation was usefully to you. I've tried many times before to explain this in other threads but sadly it can still be a difficult concept to grasp!

Cheers

D-wizzz

10th July 2004, 13:58

hello again

[QUOTE]I've tried many times before to explain this in other treads but sadly it can still be a difficult concept to grasp!

yes your right. true my reading i've encounterd many explanations on this subject,either on doom or other places.it all comes down to the same thing anyway,but i think some people have more teacher qualities in them than others.;)

youjust have to read and try,and read,and try,and read,and try etc.................

I've read alot of post on different subjects of you and i must say i enjoy reading them for me they are right to the point.KEEP IT UP!!!!

(little tab on the back doesn't hurt,right)

See ya:p

Chainmax

10th July 2004, 14:19

So, is Stux right and it's enough to select 16:9 PAL for 25 fps encodes and 16:9 NTSC for 24 and 30fps encodes in Xvid's "Aspect Ratio" tab? It's not compulsory to use MKV or MP4? I am going to try MKV on my future encodes, but it's nice to know I have a choice.

SeeMoreDigital

10th July 2004, 14:34

Originally posted by Chainmax
So, is Stux right and it's enough to select 16:9 PAL for 25 fps encodes and 16:9 NTSC for 24 and 30fps encodes in Xvid's "Aspect Ratio" tab? It's not compulsory to use MKV or MP4? I am going to try MKV on my future encodes, but it's nice to know I have a choice. Yes, it's always been as simple as this. Ever since 3ivX launched their 'anamorphic encoding' capable codec!

The ecodes work a charm when muxed into the MP4 container. Don't know about MKV though.... I mean, what is the point ;)

Cheers

Splashdriver

11th July 2004, 08:29

I've installed 3ivx (hmmm...quite interesting thing) and it seems that the mp4 file is now correctly resized in MPC (720x432 --> 1046x432) where it previously wasn't (well, to be more accurate, without 3ivx just the 720x432 image was displayed, that's all). Now back to my anamorphic encoding question. I stil think something is wrong in the process, so I will try to explain every step more accurately. I hope someone familiar with Gknot can tell me what I'm doing wrong.

First of all, I open my .d2v in Gknot. Under the 'Input Pixel Aspect Ratio' I set Dislay AR to 1.25 (Source is Pal DVD). Then I go the Crop (Before resize!) part and select Auto-crop W and H-module are both set to 16). Now I end up with a resolution of 720x416 (aspect ratio 1.731 and aspect error -1.2%).
But under the Crop (Before resize!) part it's showing res. 718x420 with a aspect ratio of 1.710.
Good, I now hit Smart Crop Left-Right and resolution now becomes 720x432 with an Aspect Ratio of 1.667 and Aspect Error of -0.6%. Notice that under the Crop (Before resize!) part resolution is now shown as 696x420 with an aspect ratio of 1.657. Hitting Smart Crop All outputs a resolution of 720x416 (aspect ratio 1.731 - aspect error 0.4%), where Crop (Before resize!) says 716x412 with an Aspect ratio of 1.738. Since we like to have 720x432 I just leave it on Smart Crop Left-Right, right???
Time to save the .avs script looking something like this:

# PLUGINS
LoadPlugin("C:\PROGRA~1\GORDIA~1\mpeg2dec3.dll")
LoadPlugin("C:\PROGRA~1\GORDIA~1\decomb.dll")
mpeg2source("F:\LOTR_The Return of the King\LOTR_The Return of the King.d2v", idct=0)

# CROPPING
crop(12,76,696,420)

# RESIZING
#LanczosResize(720,432)

When opening the script in VDubMod (v.1.5.10.1) under the File -->File information it gave me the following:
http://img43.exs.cx/img43/9784/Avi-inf_VDubmod1.png

Now My question is: Shouldn't I have 720x432 as resolution and why can't Gknot give this resolution without leaving a bit of the black bars in the image (I've been playing with it, but just can't get it right)????

Before I forget: Making mmg extract the aspect ratio information from the MPEG-4 data results in a display dimension of 1012/420....Shouldn't we aim for 1046x432 (like the the short test-files SeeMoreDigital previously posted)???

Sorry for the long post, I hope it's still somehow useful.

thanks in advance,
Splashdriver

Surco

11th July 2004, 11:24

Hi
The problem comes from here
Originally posted by Splashdriver
# RESIZING
#LanczosResize(720,432)

It should looks like

# RESIZING
LanczosResize(720,432)

A typo in your avisynth script i suppose ;)

Bye

EDIT: grammar.

SeeMoreDigital

11th July 2004, 12:37

Originally posted by Splashdriver
I've installed 3ivx (hmmm...quite interesting thing) and it seems that the mp4 file is now correctly resized in MPC (720x432 --> 1046x432) where it previously wasn't (well, to be more accurate, without 3ivx just the 720x432 image was displayed, that's all). Well this makes a good start. At least you can understand the power of the MP4 container over AVI, when it comes to anamorphic decoding!

Originally posted by Splashdriver
Now My question is: Shouldn't I have 720x432 as resolution and why can't Gknot give this resolution without leaving a bit of the black bars in the image (I've been playing with it, but just can't get it right)???? Unfortunately I don't use GK so I can't comment about how well it crops. Or if it's able to crop in a logical manner!

And just to confuse you even more :D, you will also find that not all 2.35:1 movies are exactly 2.35:1. Some are very badly centred. Some contain vertical mattes (aka over-scan mattes). Some, like my Blade Runner DVD are not 2.35:1 at all.

All I can say is that when cropping from a 720x576 anamorphic wide-screen source where the original movies AR is 2.35:1, the number of image pixels should be 432 (to the nearest 16th pixel). And you should not have to resize anything.

Cheers

Splashdriver

11th July 2004, 13:41

Originally posted by Surco
Hi
The problem comes from here

It should looks like

# RESIZING
LanczosResize(720,432)

A typo in your avisynth script i suppose ;)

Bye

EDIT: grammar.

Well Surco, I thought the idea of anamorphic encoding was to NOT do any resizing. That's why I didn't enable resizing in my avisynth script.

@SeeMoreDigital

Your explanations are quite clear and understandable. I'm still wondering why I can't get this thing to work. Maybe it's because the DVD just says 16:9 widescreen and nothing about anamorphic stuff??....

I've seen some anamorphically encoded MPEG-4 files which just resizes correctly and looks amazing too (muxed into a MKV container), so I think I do realize what's the power of anamorphic decoding. MP4 seems nice to me, but to be honest, I don't really see the advantage over MKV. Maybe it all depends on personal preference or it may be me being the ignorant one:D ...I don't know

stephanV

11th July 2004, 13:52

696x420 are the frame-dimension to which you crop and VirtualDub shows that info... i dont understand whats wrong? you should see resolution/frame dimensions seperate from aspect ratio.

SeeMoreDigital

11th July 2004, 13:57

Originally posted by Splashdriver
Your explanations are quite clear and understandable. I'm still wondering why I can't get this thing to work. Maybe it's because the DVD just says 16:9 widescreen and nothing about anamorphic stuff??.... Well I guess you might have a DVD with 4:3 Mpeg2 signalling rather than 16:9!

Can you capture an 720x576 Mpeg2 still frame an upload it please?

Cheers

Surco

11th July 2004, 14:06

Sorry, i read too fast and missed the point my apologies :(

Splashdriver

11th July 2004, 15:09

- Apology accepted Surco;) -

Now, according to DVD2avi the source is 16:9, just like the description
on the back-cover (Guess you're trying to say that this information may not always be as accurate as supposed to..)anyhow....

Here's an example captured with PowerDVD 5:

http://img40.exs.cx/img40/139/PDVD_000.png

Is there something that you can tell from this frame?

[edit]when playbacked the whole picture is obviously stretched horizontally with big black bars above and below the frame. As far as I know, PowerDvd doesn't allow one to capture such a frame, guess it can only capture frames the way it's originally stored on the disc meaning the whole picture in original state seems much more...ehm...squished. I like my encodes to be stretched correctly so objects don't look so large, that's the purpose[edit].

Thanks,
Splashdriver

SeeMoreDigital

11th July 2004, 15:21

Yep,

It is a 16:9 widescreen anamorphic DVD. So there's no problem with your disc!

If it had been an 2.35:1 image with 4:3 Mpeg2 signalling it would have looked like this: -

http://img33.exs.cx/img33/8408/SMD_43_2351_image.jpg

Note how much more matte is contained within the 720x576 pixel frame.

Cheers

Splashdriver

11th July 2004, 15:40

Edited previous post

SeeMoreDigital

11th July 2004, 15:58

Originally posted by Splashdriver
... when playbacked the whole picture is obviously stretched horizontally with big black bars above and below the frame.... guess it can only capture frames the way it's originally stored on the disc meaning the whole picture in original state seems much more...ehm...squished. I like my encodes to be stretched correctly so objects don't look so large, that's the purpose[edit]. What you are seeing is the whole point about anamorphic images!

It's very important that you understand exactly what an anamorphic image looks like prior to correction.

Cheers

gircobain

11th July 2004, 16:16

Originally posted by Splashdriver
# CROPPING
crop(12,76,696,420)

Shouldn't it be crop(0,76,720,420)?
Even though I think you'd be better off with crop(0,76,720,424) (mod8) or crop(0,80,720,416) (mod16)
Then in mmg set aspect ratio to 2.35
Isn't it simple like that? Or maybe I'm overlooking something...

Splashdriver

11th July 2004, 16:59

crop(12,76,696,420)or sometimes (12,76,696,416) is the result of doing a 'smart crop left-right' in GKnot. I've been advised by SeeMoreDigital to aim for 720x432, so that's what I'm trying to do. Unfortunately(?) when I select 720x432 as my resolution in Gknot, Avisynth automatically outputs values that resizes the picture to 696x420/416 (the same as under crop (before resize!) after I hit save (script). Guess I could manually edit the script and enter different crop values. The point is still that I don't wan't any black borders left. When entering manually an aspect ratio (1.667) in GKnot, resolution changed to 720x432, but.....there where still a bit off the black borders left. Cropping them off leads to resolution that's lower than
720x432. I'm a bit puzzled now....