[Ffmpeg-devel] About swscale

Luca Abeni lucabe72
Wed Jun 14 13:15:40 CEST 2006


On Tue, 2006-06-13 at 14:13 +0200, Luca Abeni wrote:
> The site just collects patches that I previously sent on the
> ffmpeg-devel and mplayer-dev-eng mailing lists (I think I addressed all
> the comments and feedbacks, but I could be wrong), and I hope they can
> be applied in an incremental way.
> > so what dependancies are there between the patches?
> Sorry for not being clear about that... Tomorrow I'll send a more
> detailed email explaining the dependencies and summarizing my plan.
Here we are:
1) First of all, we have the 2 mplayer patches at
(already posted to the mplayer-dev-eng mailing list, and attached to
this email).
- mplayer-headers-cleanup2.diff does not depend on anything, and just
does a cleanup on swscale headers usage in the mplayer tree (for
example, some of the mplayer files currently include private swscale
- mplayer-sws.diff depends on mplayer-headers-cleanup2.diff, and
modifies mplayer so that it can be compiled when swscale is moved from
postproc to libswscale, coping with the changes needed for compiling
swscale in the ffmpeg tree.
Since I did not receive much feedback on this patch, I left it as it is,
but if needed I can split it in two parts: one for coping with the
postproc ---> libswscale move, and one for coping with the
sws_global_init() thing.
This patch should be applied when swscale is moved to the ffmpeg tree
(and an "svn:externals" property is added to download it in
This patch should work even if swscale.diff is not applied

2) The swscale.diff patch (also attached), to move swscale out of the
mplayer tree. This patch has been posted on this mailing list some time
ago, and I hope I addressed all the comments. It has also been posted on
mplayer-dev-eng; I received some comments about the Makefile, and I
fixed it according to such comments.
The patch:
  - introduces some files and modifies the makefile to allow building
    swscale out of the mplayer tree
  - introduces the sws_global_init() function we discussed some time
    ago (allowing to set the functions used for output and for 
    allocating/freeing memory)
  - introduces a SWS_FFMPEG_FORMATS flag allowing to use ffmpeg pixel
    format names.
This last thing is temporary, and will be removed in a second time.
This patch should be applied after moving swscale to the ffmpeg tree,
and breaks mplayer unless mplayer-sws.diff is applied.
Note that the patch changed since the last time I posted it, because the
swscale code changed (if I remember well, I had to introduce the
asmalign.h file in the patch, and to do some other changes).

3) The ffmpeg patches in http://feanor.sssup.it/~luca/SwS/patches permit
to used swscale in ffmpeg once it has been moved and swscale.diff has
been applied.
These patches can be applied in a second time, after the move has
happened, so I only briefly describe them here:
- fix-avcodec-swscale.diff does not depend on anything, and just adds a
dummy SWS_FFMPEG_FORMATS definition in libavcodec/swscale.h (it will be
needed by the following 3 patches)
- move-ffmpeg-to-sws.diff changes ffmpeg.c to use the swscale interface.
If the "real" swscale is not compiled in, the wrapper already present in
libavcodec/imgresample.c is used. This patch depends on
- move-ffplay-to-sws.diff does the same for ffplay.c
- move-output_example-to-sws.diff idem for output_example
- sws-internal-newer.diff modifies configure and the build system to
allow building and using swscale instead of the "old" ffmpeg code (this
need --enable-gpl, of course). This patch depends on the previous ones.
I already posted a previous version of these patches, but the build
system changed a lot in the meanwhile so I split the configure/build
changes in sws-internal-newer.diff and I ported such patch to the
current code.

Well, I hope this description is not too confusing... ;-)

Proud to be "coglione"

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