[FFmpeg-devel] [PATCH 1/5] lavc : yami : add libyami decoder/encoder

Timothy Gu timothygu99 at gmail.com
Tue Aug 16 06:07:23 EEST 2016


On Mon, Aug 15, 2016 at 7:44 PM Jun Zhao <mypopydev at gmail.com> wrote:

> On 2016/8/16 10:14, Chao Liu wrote:
> > Sorry for this little diversion: what are the differences between QSV and
> > vaapi?
> > My understanding is that QSV has better performance, while vaapi supports
> > more decoders / encoders. Is that correct?
> > It would be nice if there are some data showing the speed of these HW
> > accelerated decoders / encoders.
> QSV has better performance is right, but libyami have more
> decoders/encoders than
> vaapi hw accel decoder/encoder. :)

I am not sure where you got this information.

On Intel platforms they all use the same chip. Because VAAPI supports more
than just Intel platforms, VAAPI supports all codecs libyami and QSV
support, if not more.

QSV works on both Windows and Linux, although it is a pain to set up a
Linux QSV environment (you have to have the right distro, right kernel,

> According our profile, the speed of QSV/Libyami/vaapi-hw accel decoder and
> native
> vaapi encoder are: QSV > ffmpeg and libyami > vaapi-hw accel decoder and
> native
> vaapi encoder

You didn't mention _how_ you profiled things, and for HW encoding different
ways of profiling can cause wildly different results. If for example you
are not doing zero-copy VAAPI operations, you are inherently giving the
other two methods an edge.


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