[Libva] gstreamer-vaapi strange issue

Wed Nov 11 04:07:58 PST 2015

Hello,

The bug report is at: https://bugzilla.gnome.org/show_bug.cgi?id=757941

Thanks again,
Bill
________________________________________
From: Libva [libva-bounces at lists.freedesktop.org] on behalf of William Katsak [william.katsak at ericsson.com]
Sent: Wednesday, 11 November 2015 6:38 AM
To: Sreerenj; libva at lists.freedesktop.org
Subject: Re: [Libva] gstreamer-vaapi strange issue

Hello,

Thanks very much for your reply. The way you described it is what I inferred from the source.

What I had expected was that setting the capsfilter would tell the encoder to use whatever tools are available that are part of the specified profile. For example, if my vainfo reports these:

      VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
      VAProfileH264Main               : VAEntrypointEncSlice
      VAProfileH264High               : VAEntrypointEncSlice

I would have liked to be able to specify profile=high, and have whatever tools are part of VAProfileH264Main selected. Indeed, I think this is how x264enc works (and maybe gstreamer-omx too?).

I will open the bug report shortly, but, I wanted to, ask something else: If I need to approximate the behaviour for some experiments, is it reasonable to just ask for whatever tools are part of each profile? Is there any way to see exactly what would be part of each profile (other than checking the standard)? Is the set of options exported to gstreamer inclusive of everything in the VAProfiles?

Thanks so much again,
Bill Katsak
________________________________________
From: Libva [libva-bounces at lists.freedesktop.org] on behalf of Sreerenj [sreerenj.balachandran at intel.com]
Sent: Wednesday, 11 November 2015 5:40 AM
To: libva at lists.freedesktop.org
Subject: Re: [Libva] gstreamer-vaapi strange issue

Hi,

Right now gst-vaapi-encoder doesn't have support to negotiate the custom
profile  set via capsfilter. But we are
selecting an appropriate profile based on other coding tools.  We start
from "constrained-baseline" as the default choice,
then if user ask for b frame encoding or cabac entropy coding, it will
switch to "main" profile.. Similarly asking for 8x8 dct
will switch  the profile to "high"..

Basically if you are not choosing any of those coding tools, it could be
enough to use constrained-baseline..
Any decoder which can support main profile should be able enough to
decode the constrained-baseline too.
Similarly high profile decoder can decode main profile too..

But adding a provision for selecting profiles as per user's choice seems
fine for me.
If you can file a bug against gstreamer-vaapi
(https://bugzilla.gnome.org/enter_bug.cgi?product=gstreamer-vaapi)
asking for this feature,
we can discuss it there..

On 10.11.2015 20:23, William Katsak wrote:
> 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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--
Thanks
Sree

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