[Libva] gstreamer-vaapi strange issue

[William Katsak]

I've been looking at the source this afternoon, and my interpretation of it is that specifying the profile via caps is only serving a restrictive role, vs. a configuration role. Obviously, I need to study it more, but is this true? To target a different profile, do we need to specifically specify which encoding tools that we want to use?

Thanks,
Bill

________________________________________
From: Libva [libva-bounces at lists.freedesktop.org] on behalf of William Katsak [william.katsak at ericsson.com]
Sent: Tuesday, 10 November 2015 10:33 AM
To: libva at lists.freedesktop.org
Subject: [Libva] gstreamer-vaapi strange issue

Hello,

I am not sure if this the right list for this, but I am seeing a strange issue with gstreamer-vaapi on Intel Haswell.

I am doing some experimentation using gstreamer-vaapi on an Intel i3-4370 CPU. I am running libva 1.6.1, and libva Intel driver 1.6.0 on Ubuntu 15.04.

My issue is that I cannot seem to get the thing to do anything except constrained baseline, despite asking it to do other profiles.

If I do something like this:

gst-launch-1.0 filesrc location=/ramdisk/bbb_sunflower_1080p_30fps_normal.mp4 ! qtdemux ! vaapidecode ! vaapiencode_h264 ! video/x-h264,profile=high ! qtmux ! filesink location=/ramdisk/tmp.mov

It appears to work fine, but if I check with this:

avprobe -show_streams /ramdisk/tmp.mov

the output will indicate:
profile=Constrained Baseline

However, if I change the encode element to:
vaapiencode_h264 dct8x8=1
it does change the output profile.

My question is, is this correct behavior? Do we need dct8x8 to do anything higher than Constrained Baseline? If so, why? Is this a fundamental detail of H.264, or is this an implementation detail?

Thanks in advance for any help or pointers that you might able to give me.
-Bill








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