EncodingCompendium

My encoding notebook - writing things down for reference.

Software Requirements

• ffmpeg
• MediaInfo

Video Encoding

AVC

Encoding 1080p Remux to 1080p AVC (reference quality)

• Video Codec: H264 (CPU)
• FPS: Same as source
• Constant Quality: RF 16 (18 seems to be the golden quality standard, but darker scenes might still suffer with it)
• Preset: VerySlow
• Profile: High
• Level: 4.1
• Tune: film
• Advanced Parameters: deblock=-2,-2

HEVC 10-bit

Preset choice and rationale behind parameters

8-bit format is not being used at all, as it introduces a noticeable color banding on SDR sources.

On a Ryzen 3700X (8c/16t) the most viable preset is medium. It encodes with a speed of 1.0x.

Slower presets / higher CRF are not worth pursuing, as the encoding time inflates too much, and the quality improvement is debatable.

aq-mode=2 seems to yield the best result (both visually and according to SSIM).
aq-mode=1:aq-strength:1 is decent too, and it consumes less bitrate than aq-mode=2.

qcomp=0.8 influences CRF - this value seems to be the community standard for when trying to replicate AVC quality on HEVC and CRF is <= 23.

no-sao=1:no-strong-intra-smoothing=1 are a MUST to preserve quality and avoid blurriness.

Encoding 1080p Remux to 1080p HEVC-10bit

Check the script in the repo.

• Encodes the video track to HEVC 10-bit (SDR).
• Auto-crops the video.
• Copies the chapters metadata.
• Creates three audio tracks from the primary one (assuming it's high quality - 7.1 - 24bit - 48kHz)
  • Stereo track @ 192kbps
  • 5.1 track @ 384kbps
  • 7.1 track @ 512kbps
• If audio is 5.1, it skips the 7.1 track.
• Copies the first subtitle track over.

Encoding 2160p HDR10 Remux to 1080p HEVC-10but

Same as above, but we apply a lanczos scale video filter.

-vf=scale=1920:800 -sws_flags lanczos

See also HDR flags in the section below. HDR -> SDR tonemapping is totally not worth it.

Encoding 2160p HDR10 Remux to 2160p HEVC-10bit

• Video Codec: H265-10Bit (CPU)
• FPS: Same as source
• Constant Quality: EXPERIMENTING
• Preset: EXPERIMENTING
• Profile: Main10
• Level: 5.1
• Tune: none
• Advanced Parameters: aq-mode=1:aq-strength=1.0:deblock=-2,-2:qcomp=0.8:no-sao:transfer=smpte2084:colorprim=bt2020:colormatrix=bt2020nc:chromaloc=2:hdr:hdr-opt:max-cll=724,647:master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)
  • transfer=smpte2084:colorprim=bt2020:colormatrix=bt2020nc:hdr:hdr-opt HDR
  • chromaloc=2 check this on the source file with MediaInfo, make sure it's the same
  • max-cll=724,647 check this on the source file with MediaInfo, make sure it's the same
  • master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1) P3 display specification

Compare two inputs with identical number of frames

SSIM:

ffmpeg -i main.mkv -i reference.mkv -lavfi ssim -f null -

Luminance difference (Y) seems to be the most noticeable.

Interpret SSIM and PSNR

https://forum.doom9.org/showthread.php?p=1334145#post1334145

ssim: ((1-oldssim)/(1-newssim) - 1)*100 = % improvement

psnr: (new - old) / 0.05 = % improvement

Known bugs

Too many packets buffered for output stream 0:1

https://trac.ffmpeg.org/ticket/6375

Solution: -max_muxing_queue_size 1024

Some users report that using 9999 also worked.

libopus - Invalid channel layout 5.1(side) for specified mapping family -1

https://trac.ffmpeg.org/ticket/5718

FFmpeg is not remapping channels for 5.1(side) streams.
A simple audio filter can fix that: -af "channelmap=channel_layout=5.1"