[FFmpeg-devel] [PATCH RFC v2 3/3] libavutil: Add thumbnail output to vaapi_h264 decoder

Zhou, Zachary zachary.zhou at intel.com
Wed Apr 10 04:36:01 EEST 2019



> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf Of
> Carl Eugen Hoyos
> Sent: Tuesday, April 9, 2019 9:27 PM
> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH RFC v2 3/3] libavutil: Add thumbnail
> output to vaapi_h264 decoder
> 
> 2019-04-08 10:53 GMT+02:00, Zachary Zhou <zachary.zhou at intel.com>:
> > This is sample code for reference
> >
> > HW support for decode+scaling in a single HW command (VDBOX+SFC).
> 
> > The primary target usage is video analytics, but can be used playback,
> > transcoding, etc.
> 
> Yes.
> So why is the feature called "thumbnail"?
> I understand that this is one use case, but this is actually about free scaling, no?
> 
> Carl Eugen

Thanks Carl Eugen.
Yes, thumbnail is one use case, and I think it may be more common.
SFC fix function in GPU does the scaling, It supports both down scaling and up scaling.

To be honest, SFC scaling range is [0.125, 8] for both X and Y direction currently.
https://github.com/intel/media-driver/blob/master/media_driver/agnostic/common/codec/hal/codechal_decode_sfc.cpp#L823

-Zach

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