Too high bitrate

[wacco]

Hi there. First of all, this (http://forum.doom9.org/showthread.php?p=971568#post971568) is where I first posted my problem. With some great help Ive tracked the problem down to that the bitrate that xvid_encraw encodes with is twice the bitrate I've applied in MeGUI's xvid config (check that thread out for more details if you want to). (" desired video bitrate of this job: 827 kbit/s - obtained video bitrate (approximate): 1615 kbit/s"). This means that my output AVI file always gets double the size than I want it to be.

I have tried this on two computers now, with the same result. No matter what bitrate I apply when encoding to xvid, the value is about doubeled for the output file. When using x264, there is no such problem. What I am trying to encode to xvid is a concert that lasts 1 hour and 49 minutes (from an avisynth script). Does anyone have an idea? I am clueless as for why the bitrate is so much higher than the value I apply :confused: Does it have to do with the xvid profiles in MeGUI maybe? I use the bitrate calculator to find the right bitrate for the size I want, apply, then check in the xvid profile config that the correct bitrate is there as well. Here is a video of the progress I do in MeGUI before starting the encoding:

http://rapidshare.com/files/22910014/record-0.avi.html

or

http://files.to/get/406283/2192/record-0.avi

[henryho_hk]

Try the ">30%" Profile or use stronger denoising filters.

[wacco]

I still don't get the size I want. It looks like whatever bitrate I apply, I get another size than I want. If I apply my prefered bitrate in the 30% profile, I get a smaller file than if I applied it in the 45% profile. But still, I always get a bigger size than I should get considering the bitrate I applied.

[ronnylov]

Then you can decrease the output resolution.

[wacco]

Is it then normal that the encode gets a higher bitrate than the one I apply? What's the point in applying a bitrate if a much higher one will be used anyways? How would I go about getting my file the size I want then? This is pretty confusing. I mean, when I use x264, or encode with Xvid in Vdubmod, I apply a bitrate, that is used no matter how high resolution the video is :S

[eb]

Your problem is connected with max quantize numbers

Double them or more.
http://img73.imageshack.us/img73/6151/record01ja6.jpg


eb

[henryho_hk]

If you fiddle with the quantizer ranges, you will end up with a blocky image. The ">30%" profile is using a smooth matrix already and so if you are still getting oversized pictures you should use stronger denoisers/softeners in your AVS script and/or reduce the resolution.

[wacco]

Thanks for all the help guys. Henryho - so, if I use the 30% profile and apply a bitrate (say, 700 for example) and use stronger denoisers and softeners, the bitrate value that I apply WILL be the value my video is encoded with?

[henryho_hk]

The nn'% of the profiles actually refers to the compressibility test (CT) result (against a target size) which is described in another thread. When the CT result is known, we select the corresponding profile which would give the target size in good quality.

Unless you actually ran a compressibility test, no one can predict the bitrate. The denoisers might be too strong and you might end up with an undersized encode. Who knows?

[wacco]

I see. What would be a good way for me to encode my video with Xvid then, if I want the output to be encoded with, say, a bitrate of 750? If I use x264 and meGUI, I can just type in my desired bitrate/filesize using the main preset/profile. Is this not possible with xvid?

[Teegedeck]

This is explicitly NOT what the presets are for! Please read the according thread in order to get an idea why.

The x.264-profiles are a completely different thing. They are categorized by a) hardware-compatiblity and b) time vs. effort put into encoding (following the rationale: 'slower encoding produces nicer-looking video').
The XviD presets are categorized by resulting video quality vs. filesize (rationale: 'Bigger video files look better'). Why do these presets follow a different philosophy? Because the rationale of the x264 profiles is not true (at least not for XviD): Slower encoding does NOT always produce nicer-looking video! Which encoding-settings produce better-looking results depends foremost on compressibility. As I said, read that thread if you won't take my word for it.

You can of course always use XviD without the profiles and reach your desired filesize. But I guarantee that the result of what you are aiming to do will look like shite.

How do I know? Because the compression used in the 30%-profile is rather strong already, the resulting picture will never look too hot. If you use stronger compression in XviD than what the 30%-profile has to offer it simply will look like shit. Always. Guaranteed. It would be much, much smarter of you if you simply followed the good people's advice and reduced the resolution of the input video.

[wacco]

This is explicitly NOT what the presets are for! Please read the according thread in order to get an idea why.

The x.264-profiles are a completely different thing. They are categorized by a) hardware-compatiblity and b) time vs. effort put into encoding (following the rationale: 'slower encoding produces nicer-looking video').
The XviD presets are categorized by resulting video quality vs. filesize (rationale: 'Bigger video files look better'). Why do these presets follow a different philosophy? Because the rationale of the x264 profiles is not true (at least not for XviD): Slower encoding does NOT always produce nicer-looking video! Which encoding-settings produce better-looking results depends foremost on compressibility. As I said, read that thread if you won't take my word for it.

You can of course always use XviD without the profiles and reach your desired filesize. But I guarantee that the result of what you are aiming to do will look like shite.

How do I know? Because the compression used in the 30%-profile is rather strong already, the resulting picture will never look too hot. If you use stronger compression in XviD than what the 30%-profile has to offer it simply will look like shit. Always. Guaranteed. It would be much, much smarter of you if you simply followed the good people's advice and reduced the resolution of the input video.

Thanks. That made it clear :)