[FFmpeg-devel] [PATCH] avfilter/vf_transpose adding NPP transpose filter

Roman Arzumanyan rarzumanyan at nvidia.com
Tue Sep 4 10:43:10 EEST 2018

Hi Timo,

Refactored the patch according to your review:
1. It actually does the rotation, so renamed the filter.
2. Replaced "t" with the "a" & "angle" cli options like in vf_rotate filter. Though supporting rotation angle multiple of 90 degrees.
3. Added the config dependency (not sure if I've done it the right way).

Cmd to check:
ffmpeg.exe ^
-hwaccel cuvid ^
-codec:v h264_cuvid ^
-i input_240.mp4 ^
-vcodec h264_nvenc ^
-vf rotate_npp="a=180" ^
-y rotate_npp_180.mp4

-----Original Message-----
From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Timo Rothenpieler
Sent: Monday, September 3, 2018 1:43 PM
To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>; Roman Arzumanyan <rarzumanyan at nvidia.com>
Cc: Yogender Gupta <ygupta at nvidia.com>
Subject: Re: [FFmpeg-devel] [PATCH] avfilter/vf_transpose adding NPP transpose filter

Minus the missing configure dependency, documentation entry and minor bump, the filter looks fine to me code wise.

Two issues though:

 From my understanding, it's not a transpose filter, but a rotation one, fixed to 90 degree angles. Unless I'm missing something in the code, it's not doing any actual flipping, like vf_transpose does.
It should also be calling nppiTranspose_8u_C1R somewhere after/before the call to nppiRotate_8u_C1R. Or use a transformation matrix to do the transposition in one step, assuming libnpp has a function for that.

It's possible that I missed it doing the transpose somewhere, so please correct me if I'm wrong.

I'd also strongly prefer this filter to be compatible with the arguments of normal vf_transpose, and behave the same for the same arguments. 
Additional parameters with more functions are fine.


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