[FFmpeg-devel] [PATCH RFC v2 2/3] libavcodec: Add thumbnail output to vaapi_h264 decoder
zachary.zhou at intel.com
Wed Apr 10 04:57:36 EEST 2019
> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf Of
> Mark Thompson
> Sent: Wednesday, April 10, 2019 6:27 AM
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH RFC v2 2/3] libavcodec: Add thumbnail
> output to vaapi_h264 decoder
> On 08/04/2019 09:53, Zachary Zhou wrote:
> > 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.
> > For VAAPI -
> > https://github.com/intel/libva
> > basically, it allows multiple outputs (in different resolutions) using the
> decode context in a single call (you can search for “additional_outputs” in
> > VAAPI sample code -
> > https://github.com/intel/libva-utils/commit/957a269f02b00760b7e807643c
> > 821ee26abc529b
> > ---
> > libavcodec/avcodec.h | 8 +++
> > libavcodec/decode.c | 16 +++++
> > libavcodec/options_table.h | 4 ++
> > libavcodec/vaapi_decode.c | 122
> > ++++++++++++++++++++++++++++++++++---
> > libavcodec/vaapi_decode.h | 30 +++++++++
> > libavcodec/vaapi_h264.c | 13 ++++
> > 6 files changed, 185 insertions(+), 8 deletions(-)
> This doesn't fit into the libavcodec API at all. If it is desirable to have some
> sort of generic multiple-output mechanism in libavcodec, please open a
> separate discussion considering that API specifically.
> For the particular hardware instance you are talking about here, can you
> explain what this mechanism actually helps with? My understanding was that
> the VDBOX / SFC chaining existed to save a small amount of power in
> restricted playback cases going directly to the display (that is, for maximising
> playback time on battery devices). Since you are writing everything back to
> memory immediately here anyway, I don't see how it helps compared to just
> doing the scale as a filter operation.
> - Mark
Thanks Mark, I understand it doesn't fit the libavcodec API currently, and I will open a discussion regarding multiple-output mechanism in libavcodec.
you may already know following document -
As my investigation -
- This feature can save some power and memory bandwidth.
- This feature can save the ffmpeg filters code writing for end user. it also support ARGB output for some AI use case, I think some AI cases may need ARGB input.
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> To unsubscribe, visit link above, or email ffmpeg-devel-request at ffmpeg.org
> with subject "unsubscribe".
More information about the ffmpeg-devel