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Hevc

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Reference:trac.ffmpeg.org

Overview ​

High Efficiency Video Coding (H.265).

libx265 ​

For a full list of options, run ffmpeg -h encoder=libx265.

Default H.265 codec, uses your CPU for processing.

OptionDescription
-crf[0; 51] default 28. Constant Rate Factor, where 0 is lossless and 51 is worst quality possible.
-presetQuality-speed tradeoff. Options: ultrafast superfast veryfast faster fast medium slow slower veryslow placebo.

Constant Rate Factor (CRF) ​

Choose the desired CRF and preset.

shell
ffmpeg -i input.mp4 -vcodec libx265 -acodec copy -r 60 -crf 20 -preset slow output.mp4

Two-Pass Encoding ​

Decide the desired file_size in kBit (1 MiB = 8192 kBit) and get the video duration in seconds. Get the bitrate with the formula bitrate = file_size / duration. Pass the result to -b for both passes.

And as for CRF, choose the desired preset.

  1. On the first pass, set -y -an -x265-params pass=1 -f mp4 and output to /dev/null.
  2. On the second pass, set -x265-params pass=2.
shell
ffmpeg -y -i input.mp4 -vcodec libx265 -an -r 60 -b:v 720k -preset slow -x265-params pass=1 -f mp4 /dev/null && \
ffmpeg -i input.mp4 -vcodec libx265 -acodec copy -r 60 -b:v 720k -preset slow -x265-params pass=2 output.mp4

Benchmark ​

Comparison when changing only the preset (using an old laptop). Tested inputs:

  1. Size: 638.0 MiB - Length: 3:50 - CRF 20
  2. Size: 580.8 MiB - Length: 2:37 - CRF 10
  3. Size: 580.8 MiB - Length: 2:37 - CRF 16

Encoding time - File size:

Input123
veryslow3:46:18 - 74.8 MiB4:06:27 - 170.9 MiB3:09:24 - 79.8 MiB
slower2:05:05 - 75.1 MiB2:38:03 - 171.0 MiB1:55:18 - 79.9 MiB
slow0:30:09 - 77.3 MiB0:28:26 - 171.1 MiB0:24:23 - 81.2 MiB
medium0:10:57 - 75.0 MiB0:10:37 - 159.3 MiB0:08:36 - 77.4 MiB
fast0:09:44 - 76.1 MiB0:08:26 - 155.2 MiB0:07:25 - 77.8 MiB
faster0:07:52 - 75.6 MiB0:07:05 - 154.3 MiB0:05:57 - 77.0 MiB
veryfast0:07:39 - 75.8 MiB0:07:02 - 154.8 MiB0:05:55 - 77.3 MiB
superfast0:06:09 - 73.7 MiB0:05:23 - 138.3 MiB0:04:33 - 72.2 MiB
ultrafast0:04:21 - 74.1 MiB0:03:36 - 139.2 MiB0:03:07 - 73.3 MiB

hevc_nvenc ​

For a full list of options, run ffmpeg -h encoder=hevc_nvenc.

OptionDescription
-vcodecSet to hevc_nvenc.
-cqTarget quality level. The range is 0-51. Similar to CRF?
-presetDetermines compression efficiency. Options: losslesshp lossless llhp llhq ll bd hq hp fast medium slow.