HEVC/H.265 Encoding

This is under development

H.265 (High Efficiency Video Compression - HEVC) is one of the replacements for H.264. It allows for a reduction of file size compared to H.264 of 25-50% and supports frame formats up to 8K (UHDTV). It also has support for HDR, which we go into more here.

There is Browser support for H265 on Microsoft Edge, Google Chrome and Safari, but not Firefox.

See ffmpeg h265 docs

There are four HEVC encoders available to ffmpeg:

• libx265
• hevc_videotoolbox - Available on OSX via the videotoolbox library.
• hevc_nvenc - NVIDIA GPU encoder.
• hevc_qsv - Intel Quick Sync Video Acceleration.

libx265

Supported pixel formats: yuv420p yuvj420p yuv422p yuv422p10 yuv444p10le gbrp10le gbrp12le gbrp

Example encoding:

ffmpeg -r 24 -start_number 1 -i inputfile.%04d.png -frames:v 200 -c:v libx265 \
    -pix_fmt yuv420p10le -crf 22 -preset slow -sws_flags spline+accurate_rnd+full_chroma_int \
    -vf "scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709" \
    -color_range 1 -colorspace 1 -color_primaries 1 -color_trc 2 \
    -movflags faststart -y outputfile.mp4

| – | – | | -preset medium | Can be one of ultrafast, superfast, verfast, faster, fast, medium, slow, slower, and placebo | | -crf 22 | Similar to h264, default is 28, but should be similar to crf 22 | | -x265-params lossless=1 | Does lossless encoding, -crf 0 is not required | | -tag:v hvc1 | To make it “Apple “Industry standard” compliant | | -profile main | Profile can be one of main or main10 or main12 | -movflags faststart | This re-organizes the mp4 file, so that it doesn’t have to read the whole file to start playback, useful for streaming. It can add a second or so to do this, since it does require re-writing the file. |

libx265 crf values

To help pick appropriate values with the CRF flag, we have run the Test Framework through some of the reference media.

If you are trying to map crf values from h264, VS_Fan came up with the following remapping formula:

x265_crf(x264_crf) = 1.09 * x264_crf −  4.19

This is showing CRF values against encoding time.

This is showing CRF values against file size.

This is showing CRF values against VMAF harmonic mean

libx265 preset comparisons

Below is showing a comparison of different preset values with a crf value of 18. Its showing that you really can just encode with -preset medium or -preset slow anything higher is really not gaining you anything.

This is showing CRF values against encoding time.

This is showing CRF values against file size.

This is showing CRF values against VMAF harmonic mean

hevc_videotoolbox

Supported pixel formats: bgra p010le nv12

hevc_nvenc

Supported pixel formats: yuv420p nv12 p010le yuv444p p016le yuv444p16le bgr0 bgra rgb0 rgba x2rgb10le x2bgr10le gbrp gbrp16le cuda d3d11

https://gist.github.com/jbboehr/f487b659cac086b176703c718d797f3b https://superuser.com/questions/1296374/best-settings-for-ffmpeg-with-nvenc