Really bad DivX's using "HD" mode in DivX Plus Converter

[sjdean]

I've been getting really blocky DivX conversion using DivX Plus Converter using relatively high quality MPEG2 sources. Xilisoft converter by contrast gets things pretty spot on, with a lot more clarity and more realistic colour.

Im not quite sure what Im doing wrong here.

But one thing I keep noticing, is for example one video source has a resolution of 720x480 at 29.97fps. This is what TMPGenc shows, and what Xilisoft also shows.

But DivX Plus Converter, and even Windows Media Player using the ffdshow video decoder shows the source as being 640x480.

Could this be the reason for the problems?

Any thoughts how to improve the quality? I'd use Xilisoft, but it seems to convert the audio instead of doing a passthrough like DivX.

THanks
Simon

[mike20021969]

Do you have a sample MPEG2 clip? I've used both DivX 6 converter & DivX Plus 8 converter many times and never had any problems with blockiness (usually a sign of too low a bit rate).

What profile and output settings are you using in DivX Plus?

[sjdean]

Umm. Basically it's a DVD rip as I build my XBMC media library and store my DVD's in archive. Profile is set to HD1080P. One file Im doing right now, has a bit rate of 1726kbps and a resolution of 1024x768 and I can still see artefacts in black areas, or if the screen fades from black to white. Lots of heavy pixellation.

[jagabo]

But one thing I keep noticing, is for example one video source has a resolution of 720x480 at 29.97fps. This is what TMPGenc shows, and what Xilisoft also shows.

But DivX Plus Converter, and even Windows Media Player using the ffdshow video decoder shows the source as being 640x480.

Could this be the reason for the problems?

No. The other programs are showing you the resolution of the source. Divx is showing you the size after correcting for the display aspect ratio, 4:3.

[jman98]

Umm. Basically it's a DVD rip as I build my XBMC media library and store my DVD's in archive. Profile is set to HD1080P. One file Im doing right now, has a bit rate of 1726kbps and a resolution of 1024x768 and I can still see artefacts in black areas, or if the screen fades from black to white. Lots of heavy pixellation.

Why on earth are you trying to upscale a DVD rip to that resolution? I wouldn't even recommend doing that with AviSynth's incredible collection of filters. Yes, trying to upscale DVD to slightly above 720p is going to do EXACTLY what you are seeing.

You've got some kind of false assumption here that "bigger is better". Maybe Xilisoft has better upscaling filters but I wouldn't expect great results from anything for that kind of upscaling.

[mike20021969]

Profile is set to HD1080P. One file Im doing right now, has a bit rate of 1726kbps and a resolution of 1024x768 and I can still see artefacts in black areas, or if the screen fades from black to white. Lots of heavy pixellation.

Regardless of the input, that bit rate is far too low for a 1080p profile. I'd use a minimum 2500-3000kbps for 720p, so even more for 1080p.

[sjdean]

Actually jman, sticking DivX Plus Converter in HD1080P will not upscale content. It uses the original resolution for the destination file, unless the original file is larger than your chosen profile, then it will downscale.

So a 1024x576 file in DivX Plus Converter will still come out 1024x576 in 1080P mode. But mobile mode will shrink to 320x180.

Jagabo, even if that were true, the (i) button on the source item, shows that the source resolution is 640x480. I've just tried Reference, and Reference, TMPGenc and Xilisoft all agree with each other that the resolution is 720x480.

Im confused.

Thanks again Mike, although it is the 1080P profile, whether I select 1080P or 720P, the output file size, bitrate, resolutions, all remain the same.

[mike20021969]

It uses the original resolution for the destination file, unless the original file is larger than your chosen profile, then it will downscale

Unless you put a custom size in of 1920x1080, but you don't/wouldn't gain anything extra by doing that (e.g. more quality).
I've just converted a 720x576 to 1920x1080 @ 3000kbps using DivX plus.
Not a single block in sight

[sjdean]

Yes, merely selecting the profile, doesn't mean that a lower resolution video will rise to that resolution, unless you change the setting and customise the resolution.

So I must be doing something wrong with a 1024 x 576 video at 1700~kbps video being block. Maybe I'm just being very hyper sensitive. I'll try and put some video samples together so you can see the problems I have.

Cheers
Simon

[mike20021969]

I must be doing something wrong with a 1024 x 576 video at 1700~kbps video being block.

Increase the bit rate. The 1080p profile default is far too low.
I used a minimum of 1500kbps when I used to do 640x480/360 resolutions.

[sjdean]

I must clarify this one. Although Im using the 1080P profile, Im using the default settings and so Im not outputting a 1080P video.

My understanding is that DivX Plus will output the same resolution as the source and not upscale unless I set the options to output a different resolution. So a 768x576 video will be output as 768x576 unless I set a custom resolution.

So 1700kbps is too low for 1080P, but it shouldn't be too low for 576 should it?

So in my conersions, I use the 1080P HD Profile and *default* settings. It is not outputting 1080P as the source isn't high enough. I have the following sources which all show blocking - perhaps not that major, but big enough for me:

768x576
720x480 (which Reference, TMPGenc and Xilisoft all see as 720x480 but Windows Media Player and DivX Plus sees the source as 640x480)
1024x576

[mike20021969]

Why are you using a HD profile for SD video?
Try using Home Theatre instead - Creates DivX files up to 720 x 576.
It should be ideal for your 720 x 480 input video.

Provide a sample clip if possible.

[jagabo]

So 1700kbps is too low for 1080P, but it shouldn't be too low for 576 should it?

It might be enough for 720x576, but maybe not or 1024x576. It depends on the nature of the video. If it's a slideshow 1700 kbps is enough. If it's all action, flickering lights, fire, smoke, turbulent water, etc. maybe not. Your blocky results would indicate it's not.

I haven't really used Divx's conversion program. Does it support constant quality encoding? If it does, use that instead. You'll always get the quality you ask for. There's no guessing about what bitrate your video needs.

[mike20021969]

Does it support constant quality encoding?

No, it doesn't.
He might be better moving onto the likes of Handbrake/VidCoder which DOES support Constant Quality.

[jman98]

Actually jman, sticking DivX Plus Converter in HD1080P will not upscale content. It uses the original resolution for the destination file, unless the original file is larger than your chosen profile, then it will downscale.

Fair enough. But you did also say:

Basically it's a DVD rip

So it sure seemed like you were talking about upscaling.

[jagabo]

Basically it's a DVD rip

So it sure seemed like you were talking about upscaling.

He is upscaling if he's encoding at 1024x576.

[sjdean]

To be fair (to me) my original post said I was encoding a 720x480 (source) MPEG2 file (later saying I was using the 1080P HD Profile) in DivX Plus Converter and it was converting to 640x480.

The 1080P HD Profile at default settings does not upscale hence Im really quite confused at why I need a larger bitrate than1700kbps just because I selected a profile that support a *maximum* resolution of 1920x1080 (or whatever it is).

I then went on to explain the way other formats that I was using, but at no point was I ever upcaling to "that" (1080P) resolution.

I'll grab some screen shots though and sample video to show what problems Im having.

[mike20021969]

What do you think you are gaining by using the 1080p profile?

[sjdean]

Clearly Im gaining nothing - apart from I don't have to keep flipping between profiles. All setting the profile does, is give the converter access to a higher resolution and higher bitrate if it needs it.But because the source file doesn't need it, the converter doesn't use it.

Sorry, but clearly, using a 1080P profile doesn't always produce a 1080P video. I don't even know why this is an issue.

[jagabo]

Clearly Im gaining nothing

I don't think that's true. It looks like your getting an upscale to 1024x576. Whereas the Home Theater profile would probably downscale to ~720x400. You end up with a file with better resolution. But it needs more bitrate to keep the image quality high.

[jman98]

Clearly Im gaining nothing - apart from I don't have to keep flipping between profiles. All setting the profile does, is give the converter access to a higher resolution and higher bitrate if it needs it.But because the source file doesn't need it, the converter doesn't use it.

So you have personally worked on the source code to Divx Converter and you know with 100% certainty that your statement is completely correct?

It's become apparent to me that you are one of those "help resistant" people who have already made up their minds about what they are doing and aren't interested in anything that doesn't conform to their preconceptions so I'm done here.

[sjdean]

Thanks Jagabo

Im not getting an upscale in everything though, and I still have problems in the original video I posted about (the 720 x 480 which became 640 x 480) which wasn't doing an upscale. Though I do take your point about 16:9 movies (cos they're squished 720x576 files and DivX widens the picture rather than flattens it, so with Home Theater, I do indeed get 720 / 16 * 9 = 405 height.

Anyhow, I've finally got the files available for viewing.

http://tree.blargle.homeunix.net/8r4r/

Thanks
Simon

[sjdean]

Clearly Im gaining nothing - apart from I don't have to keep flipping between profiles. All setting the profile does, is give the converter access to a higher resolution and higher bitrate if it needs it.But because the source file doesn't need it, the converter doesn't use it.

So you have personally worked on the source code to Divx Converter and you know with 100% certainty that your statement is completely correct?

No, but I know enough about software testing to know that the resultant set of files between both 1080P, 720P and HomeTheater have the same resolution, the same bitrate, and virtually the same file size, all roughly within a few bytes of each other (obviously this is on my source input of a 640x480 file). The videos all look the same. The software tells me its doing the same. The manuals and documentation state that it's the maximum resolution (it doesn't say it's going to upscale). Im fairly confident in my assertion.

What is your proof to say it does something different, apart from the fact the labels are different on the profiles?

[mike20021969]

But it needs more bitrate to keep the image quality high.

But for some reason he has something about 1726kbps...

[sjdean]

But it needs more bitrate to keep the image quality high.

But for some reason he has something about 1726kbps...

Lets get back to the 640x480 video and get that sorted first before we start on the 1024x576 video.

[mike20021969]

Lets get back to the 640x480 video and get that sorted first before we start on the 1024x576 video.

Post a short sample of your MPEG2 then we can have a play with it
EDIT: I see the links @ #22.

[jagabo]

Divx Converter didn't hit your target bitrate on the "HD" clips. They are less than 900 kbps average. It also used a crappy blend deinterlace and encoded at 29.97 fps rather than performing an inverse telecine back to 23.976 fps progressive frames. The 3000 kbps clip is really 3000 kbps but still has the crappy deinterlace. The MPG source is pretty poor to start with.

It may be the the HD profiles are assuming HD frame sizes and thereby making some other compromises that are causing it to allocate too little bitrate.

[sjdean]

Lets get back to the 640x480 video and get that sorted first before we start on the 1024x576 video.

Post a short sample of your MPEG2 then we can have a play with it
EDIT: I see the links @ #22.

Already have done, about three posts up - Samples here (including my DivX results)

Interestingly, the three "Promo" clips are looking much much better today than the conversion I did yesterday with the same settings. There's still some blockiness, but the red in the jumper/cardigan/pullover and the material is quite clearly defined. By 3000kbps the 640x480 clips are looking OK. But when the resultant file size isn't much smaller than the original VOB, it's not a lot a point of bothering.

http://tree.blargle.homeunix.net/8r4r/

[sjdean]

Divx Converter didn't hit your target bitrate on the "HD" clips. They are less than 900 kbps average. It also used a crappy blend deinterlace and encoded at 29.97 fps rather than performing an inverse telecine back to 23.976 fps progressive frames. The 3000 kbps clip is really 3000 kbps but still has the crappy deinterlace. The MPG source is pretty poor to start with.

It may be the the HD profiles are assuming HD frame sizes and thereby making some other compromises that are causing it to allocate too little bitrate.

If we're talking about the Promos, I think you could be correct about the bit rate. I encoded those using the default settings on each profile. Unfortunately there's nothing less than Home Theater and all videos come out at much the same quality (if not exactly the same).

The source MPG for "Promos" is indeed 29.97 fps, even though it's supposed to be a Region 2 DVD and PAL format... My mistake, Region 1, NTSC.

I think the Video Transfer wasn't that great, but if I can get this one cracked, Hollywood Movies will be easy in comparison!

There's doesn't seem to be any additional controls in DivX Converter for Deinterlace, so it's being crappy all by itself

At less than 900 kbps for the video bit rate, and that's average right? Im not surprised they look shocking my bad.

Let's go with this then, more grain/action will require more bitrate? 2 pass encoders should in theory be better too shouldn't they?

Thanks jagabo, thanks for taking a look for me. Can you see if you can improve things with minimal tweaking, or if you have a program that works better? Ideally Im looking for something with Audio Passthrough (which DivX Converter and it looks like Handbrake support).

Thanks
Simon

[jagabo]

Let's go with this then, more grain/action will require more bitrate?

Yes. Anything that causes successive frames to have differences will require more bitrate.

2 pass encoders should in theory be better too shouldn't they?

No. With bitrate based encoding you pick the bitrate (and hence the file size) but you don't know what the quality will be. 2-pass bitrate encoding delivers better quality than single pass bitrate encoding because the encoder can examine the video during the first pass to decide how best to allocate bitrate during the second pass. But with constant quality encoding you pick the quality and the encoder uses whatever bitrate it needs at each frame to deliver that quality. What you lose is the ability to pick the file size.

Thanks jagabo, thanks for taking a look for me. Can you see if you can improve things with minimal tweaking, or if you have a program that works better? Ideally Im looking for something with Audio Passthrough (which DivX Converter and it looks like Handbrake support).

I would look into Xvid4Psp, AutoGK, and I guess you know about Handbrake. I use DgIndex, AviSynth, and x264 to do most of my encoding these days.