[FFmpeg-devel] Codec Routing
chuck at burfoots.com
Fri Aug 22 01:55:39 CEST 2014
I have been investigating the ways and means of the 'routing' of FFMPEG
internally. I've built from source binaries with Windows and C99to89.
I build with --enable-libvpx. I was keenly interested in the ability of
libvpx to create/encode "webm" with alpha.
( output from ffprobe
ffprobe version 2.3.git Copyright (c) 2007-2014 the FFmpeg developers
built on Aug 21 2014 09:14:40 with Microsoft (R) 32-bit C/C++ Optimizing
ler Version 16.00.40219.01 for 80x86
configuration: --toolchain=msvc --enable-shared --enable-libvpx
libavutil 54. 5.100 / 54. 5.100
libavcodec 56. 0.101 / 56. 0.101
libavformat 56. 1.100 / 56. 1.100
libavdevice 56. 0.100 / 56. 0.100
libavfilter 5. 0.100 / 5. 0.100
libswscale 3. 0.100 / 3. 0.100
libswresample 1. 1.100 / 1. 1.100
Hey, it built and it 'seemed' to work. So I started digging in and then
discovered that it doesn't decode alpha yet. HA, that was a surprise.
So I started examining the "FFmpeg codec HOWTO"
printf instructions into libvpxdec.c in vpx_init() and vp8_decode().
These don't ever appear, so I also tried to do a fopen("abc.txt") and that
doesn't get created. So WHAT routes the linkage to
So I dumped --codecs and low and behold
DEV.L. vp8 On2 VP8 (decoders: vp8 libvpx ) (encoders:
DEV.L. vp9 Google VP9 (decoders: vp9 libvpx-vp9 )
(encoders: libvpx-vp9 )
There's 2 DECODERS for vp8 and vp8 and the 'internal' one is used first !
Isn't that a build bug?
Do I need to do a --disable-vp8, etc?
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