ff_vdpau* symbols are missing in libavocdec shared library

[marillat]

Hi,

Context : Debian unstable ffmpeg git 484b1cdd5303771447e15d0067a2034b0c17fdc8
same problem in 0.9 but not in 0.8.7

Build with only --enable-shared

At least all ff_vdpau* symbols are gone :

objdump -T libavcodec/libavcodec.so.53 | grep ff_vdpau

return nothing.

Christian

[Carl Eugen Hoyos]

Why should they be exported?
(They do not show up in libavcodec/vdpau.h and I believe they are intended only to be used internally by the decoders.)

[marillat]

Replying to cehoyos:

Why should they be exported?
(They do not show up in libavcodec/vdpau.h and I believe they are intended only to be used internally by the decoders.)

I don't understand because up to now these functions was in libavcodec53 (confirmed in 0.8.7) and XBMC check for ff_vdpau_vc1_decode_picture() in libavcodec to detect if VDPAU is enabled or not.

Then what is the best way to detect VDPAU presence in libavcodec ?

[Carl Eugen Hoyos]

Replying to marillat:

Replying to cehoyos:

Why should they be exported?
(They do not show up in libavcodec/vdpau.h and I believe they are intended only to be used internally by the decoders.)

I don't understand because up to now these functions was in libavcodec53 (confirmed in 0.8.7)

Since the function does not appear in any installed header, I don't think this is a good argument.

and XBMC check for ff_vdpau_vc1_decode_picture() in libavcodec to detect if VDPAU is enabled or not.

Untested patch sent to ffmpeg-devel.

Then what is the best way to detect VDPAU presence in libavcodec ?

Why is it tested in configure at all?
After all, you can configure libavcodec with --disable-decoder=h264 and xbmc will still accept the library although it won't work as expected.

Thank you for the report!

XBMC configure:
​https://github.com/xbmc/xbmc/blob/f587ca90e1c6b5fbbcb80bdc04048a4e0ca278de/configure.in#L1251

[Carl Eugen Hoyos]

Should be fixed (but untested).

[EricV]

Thanks for readding the needed symbol. Don't you think a better global could be used for detection. vdapu.h does not offer any external symbol so what about:

extern int ffmpeg_vdpau_support_enabled or something like that?

[Carl Eugen Hoyos]

Please explain why you believe this "detection" makes any sense?
Do you test if the h264 decoder is enabled when detecting libavcodec?
(Apart from the fact that adding a symbol would obviously mean you cannot detect older versions of libavcodec.)