[FFmpeg-devel] [PATCH] configure: Fix detection of vp9 decoder/encoder

[James Almer]

On 12/12/2017 6:55 AM, Felix Matouschek wrote:
> This fixes the detection of the vp9 decoder/encoder.
> 
> The vp9 decoder/encoder needs libm to successfully link, -lm was missing
> in the check_lib calls for vp9 in configure.
> 
> 0001-configure-Fix-detection-of-vp9-decoder-encoder.patch
> 
> 
> From 0b5bbd7c30f3a76b2e0ab6ceae2bfaebe944b279 Mon Sep 17 00:00:00 2001
> From: Felix Matouschek <felix at matouschek.org>
> Date: Tue, 12 Dec 2017 10:42:40 +0100
> Subject: [PATCH] configure: Fix detection of vp9 decoder/encoder
> To: ffmpeg-devel at ffmpeg.org
> 
> The vp9 decoder/encoder needs libm to successfully link,
> -lm was missing in the check_lib calls for vp9
> 
> Signed-off-by: Felix Matouschek <felix at matouschek.org>
> ---
>  configure | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/configure b/configure
> index 8cf48ae1cf..4581850fe5 100755
> --- a/configure
> +++ b/configure
> @@ -5918,11 +5918,11 @@ enabled libvpx            && {
>      }
>      enabled libvpx_vp9_decoder && {
>          check_pkg_config libvpx_vp9_decoder "vpx >= 1.4.0" "vpx/vpx_decoder.h vpx/vp8dx.h" vpx_codec_vp9_dx ||
> -            check_lib libvpx_vp9_decoder "vpx/vpx_decoder.h vpx/vp8dx.h" "vpx_codec_vp9_dx VPX_IMG_FMT_HIGHBITDEPTH" -lvpx
> +            check_lib libvpx_vp9_decoder "vpx/vpx_decoder.h vpx/vp8dx.h" "vpx_codec_vp9_dx VPX_IMG_FMT_HIGHBITDEPTH" -lvpx -lm

No, this is not correct. If anything has to be added here, it would be
$libm_extralibs. -lm is not needed/available on some systems.

Also, you should be using pkg-config. Its job is to make sure all the
cflags and ldflags are correct for your system.
This shitty fallback shouldn't be here in the first place, but some
people are too stubborn about it.

>      }
>      enabled libvpx_vp9_encoder && {
>          check_pkg_config libvpx_vp9_encoder "vpx >= 1.4.0" "vpx/vpx_encoder.h vpx/vp8cx.h" vpx_codec_vp9_cx ||
> -            check_lib libvpx_vp9_encoder "vpx/vpx_encoder.h vpx/vp8cx.h" "vpx_codec_vp9_cx VPX_IMG_FMT_HIGHBITDEPTH" -lvpx
> +            check_lib libvpx_vp9_encoder "vpx/vpx_encoder.h vpx/vp8cx.h" "vpx_codec_vp9_cx VPX_IMG_FMT_HIGHBITDEPTH" -lvpx -lm
>      }
>      if disabled_all libvpx_vp8_decoder libvpx_vp9_decoder libvpx_vp8_encoder libvpx_vp9_encoder; then
>          die "libvpx enabled but no supported decoders found"
> -- 2.14.1.windows.1
> 
> 
> 
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