[Kdenlive-devel] --disable-mmx for MLT and other options for ffmpeg

Dan Dennedy dan at dennedy.org
Wed Sep 1 18:31:49 UTC 2010

On Wed, Sep 1, 2010 at 1:27 AM, Simon A. Eugster <simon.eu at gmail.com> wrote:
> Some weeks ago I read something about MMX being supported on 64bit as well
> (but unrelated to MLT, so I skipped most of the text). Now I tried to
> compile MLT without the --disable-mmx flag, and it seems to work here (I
> don't know what MMX depends on; Using kernel 2.6.34, gcc 4.4.5).

Of course. The configure system got better, but not the documentation.

> And about ffmpeg options listed here:
> <http://kdenlive.org/user-manual/downloading-and-installing-kdenlive/installing-source/installing-ffmpeg>
> What is the use of these?
> --disable-decoder=libdirac
> --disable-encoder=libschroedinger

Arbitrary choices from the author of that page as far as I am concerned.

> And does something speak pro/contra these?
> --enable-libspeex (speech codec) [1]

Only if the libs and headers are available, but I find speex usage in
editing/post to be rather obscure, even for the FOSS amateur and
hobbyist. Personally, I would not recommend this option to be
conservative and not require the additional step of installing the

> --enable-libvpx (should speed up h264 decoding) [2]

Wrong, has nothing to do with H.264. It is required for WebM encoding.
decoding WebM VP8 can be done with either libvpx or now it is native
in ffmpeg, and the native is faster. I think you have to explicitly
choose to decode with libvpx if the lib is enabled for encoding, but I
have to confirm that. It is probably a good thing to recommend this
option and advocate WebM, but the page should make it clear that this
is optional and has this external library dependency.

> Just wondering :)
> Simon
> [1] http://www.speex.org/
> [2]
> http://www.slashcam.de/news/single/Libvpx-optimiert-VP8-Dekoder-8524.html
> (German)


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