[FFmpeg-devel] [PATCH] configure libvpx check version of decoder only

[Frank Barchard]

On Thu, Jul 29, 2010 at 12:42 AM, Reimar D?ffinger <Reimar.Doeffinger at gmx.de
> wrote:

> On Thu, Jul 29, 2010 at 12:28:44AM -0700, Frank Barchard wrote:
> > This patch allows ffmpeg to configure and build against libvpx when it
> > just contains the decoder.
> > libvpx version checked, but only for the decoder.
>
> Uh, and then compilation just fails?


It builds correctly if you configure both libvpx and ffmpeg for decode only:
Configure libvpx with --enable-vp8-decoder and do a local 'make install'
Configure ffmpeg with --enable-decoder=libvpx and it only uses libvpxdec.c
decoder functions.
The ffmpeg build produces a smaller avcodec-52.dll that decodes webm files
correctly.

Or does libvpx always contain
> dummy symbols for the encoder?


no, with this configuration, only the decode functions are linked in.
The encode functions are referred to from libvpxenc.c which isn't used if
encoders are disabled.

In which case linking against a
> decode-only libvpx but still claiming to support encoding with
> libvpx is a bad idea.
>

ffmpeg was configured for decode only and reports it correctly:
ffmpeg -codecs
 ------
 D V    libvpx          libvpx VP8
 D VSD  theora          Theora
 D A    vorbis          Vorbis
 D VSD  vp3             On2 VP3


> Also with the native VP8 decoder I don't see a real point in
> supporting this configuration - if it was as trivial as this patch
> maybe, but it isn't.
>

For now this configuration has some useful features.
Such as the NEON support, that Jason points out.