Opened 8 years ago

Closed 7 years ago

#4025 closed defect (invalid)

Encoding speed of webm vp8 has declined signficantly

Reported by: Scott Dowdle Owned by:
Priority: minor Component: documentation
Version: git-master Keywords: libvpx
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no


Summary of the bug: Encoding speed for webm (vp8/theora) with ffmpeg 2.1.5 was significantly faster than it is now in ffmpeg 2.3.4

How to reproduce:
I primarily use the ffmpeg packages provided by rpmfusion for Fedora. In Fedora 20 the ffmpeg version available through rpmfusion is 2.1.5. I recently installed Fedora 21 pre-beta and rpmfusion rawhide has ffmpeg 2.3.4. The encoding speed for webm (vp8/theora) videos is significantly different between the versions.

I also tried a static build of the contemporary release (ffmpeg-2.4.2-64bit-static.tar.xz) and discovered that it too is very slow when encoding webm (vp8/theora) videos.

In a related note, webm (vp9/opus) works much better in newer releases and I wanted to try that out as well... but I have to wonder if the addition of vp9/opus code has slowed down the encoding speed for vp8/theora?

Both Fedora 20 and 21 pre-beta are using libvpx-1.3.0.

Command lines given:

ffmpeg -y -i source.mp4 -f webm -b:v 800k -b:a 96k -ac 2 -sn output.webm

On a Dell Optiplex 9010 with an Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz, I was getting about 80 FPS encoding with ffmpeg 2.1.5 but now with ffmpeg 2.3.4, I'm gettin about 20 FPS.

Change History (7)

comment:1 by jamal, 8 years ago

Component: undetermineddocumentation
Keywords: vpx added
Priority: normalminor
Status: newopen

Looking at the history of libvpxenc.c, it seems the one of the default settings was changed starting with ffmpeg 2.2, commit 34e32d6464135a03da14d5b0aef1d42796939eae (Changing the speed/cpu-used setting from 3 to 1).

If you use the default settings (Like you're doing with the command line example you gave above) then it will of course be slower now since we default to a slower but higher quality encoding setting.

For an approximation of the old behavior back try running something like "ffmpeg -y -i source.mp4 -f webm -cpu-used 3 -b:v 800k -b:a 96k -ac 2 -sn output.webm".

comment:2 by Carl Eugen Hoyos, 8 years ago

Keywords: libvpx added; vpx removed
Version: unspecifiedgit-master

I still wonder how this ticket is related to theora...

in reply to:  2 comment:3 by jamal, 8 years ago

Summary: Encoding speed of webm (vp8/theora) has declined signficantlyEncoding speed of webm vp8 has declined signficantly

Replying to cehoyos:

I still wonder how this ticket is related to theora...

It isn't. dowdle most likely meant to say vorbis.

comment:4 by Scott Dowdle, 8 years ago

Yes, I confused the two. Sorry.

So, can anyone confirm the significant reduction in encoding speeds? It is very consistent for me on multiple machines with the same source material.

comment:5 by Carl Eugen Hoyos, 8 years ago

You can confirm it yourself, just follow the link above: The default was changed to higher quality / slower speed, just increase the speed with -speed 3 to get the old behaviour (that was not documented afaict).

comment:6 by Scott Dowdle, 8 years ago

DUH, somehow I overlooked the answer provided. Thanks!

comment:7 by Elon Musk, 7 years ago

Resolution: invalid
Status: openclosed
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