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Windows => JRiver Media Center 34 for Windows => Topic started by: BryanC on May 05, 2025, 09:09:42 pm

Title: Tonemapping H265->H264 library client video conversions and/or using H265?
Post by: BryanC on May 05, 2025, 09:09:42 pm

The H264 SDR streams I'm receiving on my clients from my server's HDR H265 files look washed out. Could these be tonemapped or have more configurable scaling/quality presets exposed?

Is H265 encoding still unfeasible? In addition to lowering bandwidth for SDR/HDR, it would significantly reduce the performance requirements of a client renderer when receiving bandwidth-constrained HDR transcodings and using HDR passthrough. Also I just generally prefer the aesthetic of H265 because it has less blocking and banding.

Title: Re: Tonemapping H265->H264 library client video conversions and/or using H265?
Post by: mattkhan on May 06, 2025, 03:16:17 am

Iirc encoding is CPU only so I would think tone mapping is not feasible/better done on the client

Title: Re: Tonemapping H265->H264 library client video conversions and/or using H265?
Post by: BryanC on May 06, 2025, 09:35:20 am

My server has a lot of CPU horsepower while my thin clients do not have enough power to tonemap properly.

VAAPI (hardware accelerated) tonemapping is available in ffmpeg but limited to HDR10.

Even if I leave tonemapping on the CPU and just do GPU decode/encode, I can easily exceed real-time transcoding:

Code: [Select]

ffmpeg \
  -vaapi_device /dev/dri/renderD128 \
  -hwaccel vaapi -hwaccel_output_format vaapi \
  -i input.mkv \
  -vf "
    hwdownload,format=nv12,            \
    format=p010le,                     \
    zscale=transfer=linear:npl=100:range=full, \
    tonemap=hable:desat=0,             \
    zscale=transfer=bt709:range=tv,    \
    format=nv12,hwupload
  " \
  -c:v h264_vaapi -qp 18 \
  -c:a aac \
  output.mkv



Title: Re: Tonemapping H265->H264 library client video conversions and/or using H265?
Post by: Hendrik on May 08, 2025, 02:28:43 am

I do want to offer both of those options, tone-mapped encoding or encoding HDR10 H265, but its still on the TODO list, as they require quite some re-working.
H265 encoding would realistically require hardware encoding to be fast enough, but thats probably an acceptable limit.