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

[Jun Zhao]

On 2016/8/16 11:07, Timothy Gu wrote:
> Hi
> 
> 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,
> etc.).
> 
> 

I means ffmpeg_VAAPI hw accel decoder/native VAAPI encoder, not the VAAPI as 
interface.

>>
>> 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.
> 

I used the ffmpeg_QSV/ffmpeg_libyami/ffmpeg_vaapi to do zero-copy mode transcode with default setting as profile case.

> Timothy
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