Encoding Xvid in 50mbps?

[24fps]

Hi all,

We shot a music video this week-end with a Canon 7D. I understand that it encodes at 48mbps, now what I'd like to do is export some of these clips out of Vegas and drop them in Vdub using an AVS script that will allow me to double the framerate.

Problem is that in the Xvid settings window I can only go as high as 20mbps even though the "unrestrained" profile is selected. I am fairly sure that I read somewhere that Xvid could encode in 50mbps.

Is this simply a question of my Xvid settings being wrong or am I wrong altogether?

Thanks

[El Heggunte]

IF that upper limit doesn't actually exist in the MPEG-4 ASP specifications, THEN it exists in the Xvid source-code (just like the 64-zone limitation, for example). In this case, you would have to re-write and re-compile the source-code.

[poisondeathray]

You should be able to, with both xvid encraw and xvid vfw; Maybe you should enter the value instead of using the slider in the GUI ?

If you're not hitting the entered value, make sure the minimum quantizers are 1

Different matrices can affect how high the maximum bitrates you can go as well - that might be the limiting factor


I remember seeing a chart that had xvid results 100-200Mb/s

http://forum.doom9.org/showthread.php?p=1510777#post1510777


If you can't figure it out, you can use another intermediate format for now


EDIT: yep, just ran a quick test you can enter a value and it works. I would consider quantizer based encoding instead of a fixed bitrate

[El Heggunte]

Good news, it seems DeathRay is right , apparently the numbers in the text box override the stupid slider.

EDIT: for a change, I still am too slow at typing

you can use another intermediate format for now

Unnecessary, just choose DivX instead of Xvid.

[24fps]

Well of I manually enter the value I end up with a 12mbps file. If I go about it with quantizer value (set to 1) I end up with a 33mbps file which is not enough. Is there any other settings that might impede on the ability to encode to a higher bitrate?

Actually I think I found an alternative way of achieving the results I am looking for. I will start a new thread but please let's not kill this one in case the alternative doesn't work out.

Thanks !

[poisondeathray]

It's related to content - The 7D produces very soft videos, so for the current settings you are using, that's all xvid will allocate


The choice of the matrix. If you use something like fox, it will probably be 5-10x larger

You can disable b-frames or lower the quantizer ratio of b-frames - this will increase size and quality

If you used all I-frames, the file size should ballon as well

[TSJNachos]

Personally, I have found that XviD often doesn't use the bitrate I specifiy (at least not when it's too high). Irronically, that's what I love about XviD. Odds are, if you cannot get the bitrate highter than it is, it's probably because XviD knows there is little benefit for doing so. In fact, unless you're working with HD videos, there's little need to go above ~2 Kb/s (depending on the video).

However, if you must have 50mbps, I would recommend using an older build of FFDshow, instead. FFDshow used to have a number of codecs built in, until the author decided to remove them. I really wish he hadn't. One of those codecs was the FFMpeg Lavc/MPEG-4 encoder. It uses the same output video format as XviD, but is less picky about the maximum size. Or, like Poisondeathray said, you could use a custom quantization matrix, with low quantizers, and all I-Frames.

[jagabo]

Well of I manually enter the value I end up with a 12mbps file. If I go about it with quantizer value (set to 1) I end up with a 33mbps file which is not enough. Is there any other settings that might impede on the ability to encode to a higher bitrate?

Disable B-frames. If that's not enough then set the GOP size to 1 (all I frames). If that's not enough use a high detail matrix. But your quest for bitrate is arbitrary.

[Nelson37]

This camera encodes in Xvid? Or is it Digital Video format, making the bitrate totally meaningless when translating to a different format?

[24fps]

Nelson: It records in h.264 and puts it in a QT file.

Jagabo: My quest is mainly because I need to find a solution that is as lossless as possible in order to avoid degradation as much as possible.

Also, where can I disable B-Frames, I've looked but couldn't that option, same goes for GOP size.

Thanks

[poisondeathray]

My quest is mainly because I need to find a solution that is as lossless as possible in order to avoid degradation as much as possible.

Then you should use a lossless format. Something like lagarith, huffyuv, ut video codec, or uncompressed . Or frameserve out with debugmode as mentioned in the other thread

Also, where can I disable B-Frames, I've looked but couldn't that option, same goes for GOP size.

In the xvid vfw configuration, push the "more" button beside the profile box , a submenu will open, uncheckmark B-VOPs to disable b-frames

Similarly, beside the quality preset box, push the "more" button. Make sure it's set to user defined first in the drop down box. Enter the value for the maximum I-frame interval for the GOP size. "1" would give you I frames only

[Cornucopia]

If you're looking for as lossless as possible (aka as little degradation as possible), then don't waste your time with a destination codec like Xvid (or DivX). Use either an uncompressed, or losslessly compressed video (Lagarith, HuffYUV), or visually-lossless lossy codec (Cineform, DNxHD).

That's like saying, "I want to travel faster than a racehorse. Hmm, should I take my bicycle and soupe it up with a motor? Maybe 2 motors?!!" No, you would forget the bicycle format and get a motorcycle or car (or train or plane or spaceship/rocket, etc - whichever you can afford). Think outside the box.

Scott