[FFmpeg-devel] [PATCH] build: rely on pkg-config for libx264 probing / Hijacked Changelog discussion

[Michael Niedermayer]

On Wed, May 14, 2014 at 06:51:52PM +0200, Clément Bœsch wrote:
> On Tue, Dec 17, 2013 at 02:00:52PM +0000, Carl Eugen Hoyos wrote:
> > Clément Bœsch <u <at> pkh.me> writes:
> > 
> > > before:
> > >   ./configure --enable-gpl --enable-libx264 
> > > --extra-cflags="-I/usr/local/include" --extra-ldflags="-L/usr/local/lib"
> > > after:
> > >   PKG_CONFIG_PATH=/usr/local/lib/pkgconfig ./configure 
> > > --enable-gpl --enable-libx264
> > 
> > As said, I am mildly against this because I don't see 
> > what it fixes (you still need a specific configure line) 
> 
> It fixes the need to add -I and -L flags. It also ease the creation of static
> build: typically, with the help of --pkg-config-flags="--static" it will allow
> these flags to be automatically added:
> 
>   ☭ pkg-config --libs --static x264
>   -lx264 -lpthread -lm -ldl 
> 
> Note that when this kind of option is enabled, it is automatically applied to
> any library where we use pkg-config. Since we use pkg-config for quite a bunch
> of libraries, this should be expected (maybe the detection mechanism used for
> each library could be documented).
> 
> Basically, as said in the original mail, I see pkg-config as a more reliable,
> simpler and expected way for handling all the dependency needs and ease
> multiple installations.
> 
> BTW, the following diff is actually simpler:
> 
> -enabled libx264           && require libx264 x264.h x264_encoder_encode -lx264 &&
> -                             { check_cpp_condition x264.h "X264_BUILD >= 118" ||
> -                               die "ERROR: libx264 must be installed and version must be >= 0.118."; }
> +enabled libx264           && require_pkg_config "x264 >= 0.118" "stdint.h x264.h" x264_encoder_encode
> 
> > but at the same time breaks existing configure lines.
> > 
> > Or doesn't it break them?
> > 
> 
> Yes, probably. Can't do much about it, these command lines are really
> workarounds for a bad detection.
> 
> Now I think this is part of a real communication problem we have with our
> downstreams. Typically, to overcome that kind of issue, I would suggest to
> change our Changelog layout: we *NEED* a release note. We need to split
> features, bugfixes (important ones only probably), and behaviour changes.
> 
> Suggestion: we wipe Changelog after every release, and replace it with
> something like that:
> 
> Example inspired from i3 release notes (because it's pretty ;)):
> 
> ----8<----------------------------------------------
> 
>  ┌──────────────────────────────┐
>  │ Release notes for FFmpeg 2.3 │
>  └──────────────────────────────┘
> 
>    2.3 was released blablabla
>    It includes the following library versions:
> 
>     • libavutil      xx.yy.1zz
>     • libavcodec     xx.yy.1zz
>     • libavformat    xx.yy.1zz
>     • libavdevice    xx.yy.1zz
>     • libavfilter    xx.yy.1zz
>     • libswscale     xx.yy.1zz
>     • libswresample  xx.yy.1zz
>     • libpostproc    xx.yy.1zz
> 
>    Please refer to the doc/APIChanges file for more information.
> 
>  ┌────────────────────────────┐
>  │ Features                   │
>  └────────────────────────────┘
> 
>   • AC3 fixed-point decoding
>   • shuffleplanes filter
>   • subfile protocol
>   • Phantom Cine demuxer
>   • replaygain data export
>   • VP7 video decoder
>   • Alias PIX image encoder and decoder
>   • Improvments to the BRender PIX image decoder
>   • Improvments to the XBM decoder
>   • QTKit input device
>   • improvments to OpenEXR image decoder
>   • support decoding 16-bit RLE SGI images
>   • GDI screen grabbing for Windows
>   • alternative rendition support for HTTP Live Streaming
>   • AVFoundation input device
>   • Direct Stream Digital (DSD) decoder
>   • Magic Lantern Video (MLV) demuxer
>   • On2 AVC (Audio for Video) decoder
>   • support for decoding through DXVA2 in ffmpeg
>   • libbs2b-based stereo-to-binaural audio filter
> 
>  ┌────────────────────────────┐
>  │ Bugfixes                   │
>  └────────────────────────────┘
> 
>   • issue3327-libc-2.17.so is not a MP3 anymore
> 
>  ┌────────────────────────────┐
>  │ ⚠ Behaviour changes ⚠      │
>  └────────────────────────────┘
> 
>   • libx264 is now detected through pkg-config
> 
> ----8<----------------------------------------------
> 

looks nice


> I'm not sure for the Bugfixes section since it will probably be a pain to
> maintain, and maybe irrelevant since it might be backported.

Its maybe not so hard to maintain,
git can be used to autogenerate this:

git log n2.2.1..n2.2.2 --oneline --grep 'ixes .icket'

9d0ff64 ffmpeg: print an error at the end if conversion failed
c588316 avfilter/filtfmts: Support dynamically allocated in/outputs
e3b08b3 avformat/rtmpproto: Added handling of an initial RTMP chunk size packet.
09abca6 sws: dont use the optimized 410->420 unscaled conversion when height%4
43d6482 avcodec/vorbisdec: try to workaround libvorbisenc bug
4a479fd swresample: fix AV_CH_LAYOUT_STEREO_DOWNMIX input
4f41717 avformat/mux: Check for and remove invalid packet durations
6896dcb avformat/avidec: Speed up keyframe detection code
e9e42be avformat/asfenc: dont allow non interleaved packets
abd6dec avformat/pmpdec: remove cur_dts timestamp hack
0385c82 avformat: Fix decoder search in find stream info
30cf47c ff_id3v2_read: add option to limit ID3 magic number search
b45cd17 ff_id3v2_free_extra_meta: set the pointer pointing to extra_meta to NULL
32919db Fix compilation with --disable-everything --enable-muxer=avi --disable-network.
56f44c2 avutil/avstring: do not lose ascii characters when decoding non utf-8 with av_utf8_decode()
fe87a40 ffprobe: do not lose non ascii characters in non utf8 strings


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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