video: warn if an emulated hwdec API is used

mpv supports two hardware decoding APIs on Linux: vdpau and vaapi. Each
of these has emulation wrappers. The wrappers are usually slower and
have fewer features than their native opposites. In particular the libva
vdpau driver is practically unmaintained.

Check the vendor string and print a warning if emulation is detected.
Checking vendor strings is a very stupid thing to do, but I find the
thought of people using an emulated API for no reason worse.

Also, make --hwdec=auto never use an API that is detected as emulated.
This doesn't work quite right yet, because once one API is loaded,
vo_opengl doesn't unload it, so no hardware decoding will be used if the
first probed API (usually vdpau) is rejected. But good enough.

1 files changed, 5 insertions, 0 deletions

diff --git a/video/decode/vaapi.c b/video/decode/vaapi.c
index d9267936d0..2b951fd1bb 100644
--- a/video/decode/vaapi.c
+++ b/video/decode/vaapi.c
@@ -409,6 +409,8 @@ static int probe(struct vd_lavc_hwdec *hwdec, struct mp_hwdec_info *info,
         return HWDEC_ERR_NO_CTX;
     if (!hwdec_check_codec_support(decoder, profiles))
         return HWDEC_ERR_NO_CODEC;
+    if (va_guess_if_emulated(info->vaapi_ctx))
+        return HWDEC_ERR_EMULATED;
     return 0;
 }
 
@@ -418,9 +420,12 @@ static int probe_copy(struct vd_lavc_hwdec *hwdec, struct mp_hwdec_info *info,
     struct priv dummy = {mp_null_log};
     if (!create_va_dummy_ctx(&dummy))
         return HWDEC_ERR_NO_CTX;
+    bool emulated = va_guess_if_emulated(dummy.ctx);
     destroy_va_dummy_ctx(&dummy);
     if (!hwdec_check_codec_support(decoder, profiles))
         return HWDEC_ERR_NO_CODEC;
+    if (emulated)
+        return HWDEC_ERR_EMULATED;
     return 0;
 }