[FFmpeg] Up encoding speed for wmv's

[Klagar]

Hi all !

I already posted a similar issue here, but quite a bit has changed since, so I'll address my problem once again.

I upgraded my FFmpeg and had to rework some of my command lines. I'm having speed issues when trying to encode to WMV files. As a test, I input the movie Elephants Dream (in avi format). Problem is, the average encoding speed is about 10 fps. That wouldn't be "bad" in itself, but using my old command line on my old version of FFmpeg, the same encoding went twice as fast, with 20 fps average.

Here is the line I'm using right now :

-r 29.97 -vcodec wmv2 -b 8000k -bt 4000k -s 1280x720 -aspect 16:9 -ab 128k -ac 2 -acodec wmav2 -ar 44100 -b_strategy 2 -bf 0 -cmp +chroma -coder 1 -flags +loop -g 15 -i_qfactor 0.71 -me_range 32 -me_method epzs -qcomp 0.4 -qdiff 4 -qmin 3 -subcmp 2 -subq 8 -trellis 2

Could anyone tell me if something strikes him/her as being a potential cause for a slow encoding (or, alternatively, tell me if anything is missing or utterly useless in said line) ?

Maybe the problem comes from FFmpeg itself, maybe over time it got better and faster at encoding to mp4 files and slower at all the rest ? I've got the same issues with encodings to AVIs, and I figure if I can settle it with WMV I'll have a good idea what to do next.

Thanks a lot to anyone who can give me some insight !

[txporter]

Do you have a multi-core processor? I don't see a -threads X defined.

[Klagar]

I have. But whenever I define a -threads parameter FFmpeg tells me :
[wmv2 @ 035816f0] multi threaded encoding not supported by codec

[txporter]

Yeah, I just tried using that on my laptop (i5). It would just crash out of encoding (when adding -threads). I have never done any WMV encoding with ffmpeg (and have done VERY little with Windows Media Encoder/Essential). On my laptop I was getting 18-20 fps with your command line inputting an avs file doing a TIVTC + fft3dfilter + subtitling.

[gregalan]

"-coder 1 -flags +loop -i_qfactor 0.71" are only valid for x264.
epzs is the default me method so that's not required.
-bt 4000k is the default also, it's not necessary to specify values when you want the default.

The wmv2 encoder in ffmpeg is very basic, so I don't know if any of your command line is useful.

Maybe this will help:
http://www.ffmpeg.org/ffmpeg.html

[Klagar]

Thanks a lot gregalan. That's exactly the kind of info I was looking for ! I tested and it looks like you're right : the command lines with or without the options you mention yield the exact same result !

Unfortunately, unless I'm just way bad at figuring things out (which I doubt), the official FFmpeg documentation gives little to no useful advice on the matter. And serious developers often don't have (or take) the time to answer theses questions they seem to consider "n00bie questions"...