That's great! Any way for me to pull that branch or otherwise
contribute?
Have been using FFmpeg for a few years now, so hopping to be able to
give back.
On Tue, Jan 12, 2021 at 5:55 am, Lynne <d...@lynne.ee> wrote:
Jan 11, 2021, 23:27 by felix.leclair...@hotmail.com
<mailto:felix.leclair...@hotmail.com>:
Hi guys and gals, first post on this mailing list, apologies for
any formatting/stylistic snafus
TLDR; we currently have tone mapping filters (typically used to map
content from a 10bit HDR source to an 8bit SDR output) that are done
on CPU with Zscale from Zlib, or hardware implementations using
VAAPI or OpenCL. Having a version implemented in CUDA would round
out the main HWaccels types.
Context:
I'm a computer engineering student up in Canada with an interest
in high efficiency distributed processing. As a personal project I'm
trying to build a cluster of Nvidia Jetson Nano's to be able to
handle a few dozen streams (mix of SD, HD, FHD, UHD, 4kHDR) at once
while drawing south of 100W at peak. These little devices can do
anywhere from 1 to 9 streams of content at a time depending on
resolution/framerate in hardware in any mix of HEVC or H.264, so 3
of them should get me most of the way to where I want to go (this
would be a 30W package capable of ~12 2160p30@10 bit -> 1080p30 8bit
streams).
The issue is that, 4 little arm64 cores are just not going to be
able to tonemap using Zscale in real time, even with the encoder and
decoders sharing memory with the CPU (so no PCIe memcopy penalty).
On the other hand, the built in GPU and the relative simplicity of
most tone mapping algorithms (say hable) should make quick work of
this. Unfortunately (or fortunately for me to learn with?) there
isn't a CUDA version of the filter.
Question/guidance:
I've read through the doc on how to write filters, as well as
looking at the other cuda filters currently in the source and have a
general idea of where I'm going, but haven't been able to fully nail
down how to access frames from hwupload_cuda passed to
vf_tonemap_cuda.c which in turn passes that frame to
vf_tonemap_cuda.cu for processing. I have a repo with everything
I've been pulling together for my project, but the piece of interest
is under */cuda_filter/ in the source tree.
<<https://github.com/Camofelix/Jetson_ffmpeg_trancode_cluster/>>
Would anyone mind helping me out with how to architect this?
The tonemap filter is just a (very old by now) copy of libplacebo's
tonemapping.
No one has bothered to keep it in sync.
I'm working on a libplacebo wrapper currently, so once that's merged
there
will be up to date hardware tonemapping.
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