Shell script that encodes a movie to HEVC using Intel's lesser known SVT-HEVC encoder

transcode-svt-hevc.sh

#!/bin/sh

# File from which the video is taken
inputFile=$1

# File to which the HEVC-encoded video bitstream will be written
hevcFile=${inputFile%.*}.hevctranscoded.hevc

# File to which the final generated output video will be written
outputFile=${inputFile%.*}.hevctranscoded.mkv

# This should output the number of video frames
# ...but it doesn't work
#
#ffprobe \
#	-v error \
#	-select_streams v:0 \
#	-count_frames \
#	-show_entries stream=nb_read_packets \
#	-of csv=p=0 \
#	-i "$inputFile"
#
#
# This is slower and it does work. But careful, ffmpeg does not
# print a line on every frame but after 1 second or so elapsed,
# so perhaps the count can be off by a few frames?
#
#ffmpeg \
#	-i "$inputFile" \
#	-vcodec copy \
#	-f rawvideo \
#	-y \
#	/dev/null
#
#
# This seems to agree with ffmpeg and may be more reliable:
#
#mediainfo \
#	--fullscan \
#	"$inputFile" \
#	| grep -i "frame count"
#

# Number of frames to encode
#
# Check: can this be left out ot automated somehow?
# For now, I'll set it to a ridiculously low value so it becomes
# obvious if the parameter is forgotten without spending too much time.
: ${frameCount:=100}

# Dimensions of the video
: ${videoWidth:=1920}
: ${videoHeight:=1080}

# Bits per second to use for the video and audio streams
#
# Suggested for stereo movies     | Suggested for 5.1 movies
# --------------------------------|--------------------------------
#    768 =  672 video +  96 audio
#   1024 =  928 video +  96 audio
#   1536 = 1408 video + 128 audio   1536 = 1280 video + 256 audio
#   2048 = 1920 video + 128 audio   2048 = 1792 video + 256 audio
#   2560 = 2432 video + 128 audio   2560 = 2152 video + 384 audio
#   3072 = 2944 video + 128 audio   3072 = 2688 video + 384 audio
#   4096 = 3968 video + 128 audio   4096 = 3712 video + 384 audio
#   5120 = 4992 video + 128 audio   5120 = 4736 video + 384 audio
#                                   6144 = 5670 video + 384 audio
#: ${videoBitRate:=2359296}
: ${videoBitRate:=2574187}

# Tell HEVC-SVT about the frame rate of the encoded movie.
#
# This is pretty much pointless because the encoder will mess up so badly
# that, at the VERY latest, after 1 minute the video is too far out of sync
# to even associate spoken dialogue with its character...
#
: ${videoFrameRateNum:=24000}
: ${videoFrameRateDenom:=1001}

# Whether to do a 10-bit encode
#
# Ten bit encodes are claimed to avoid banding. I've yet to see any
# any banding in a 'veryslow' encode, but it also doesn't increase
# bit rate requirements by that much, so I default to yes.
#
: ${tenBit:=false}

# Whether to sharpen the video
#
: ${sharpenVideo:=true}

# ----------------------------------------------------------------------------

ffmpegParameters=()
svtParameters=()

if $sharpenVideo ; then
	echo Sharpening enabled
	ffmpegParameters+=(-filter:v "smartblur=lr=2.0:ls=-0.5:lt=-3.5:cr=1.0:cs=-0.25:ct=-1.5")
fi

# We use the 'main' rather than the 'high' tier. The tier does
# not enable any advanced encoding technology, it merely switches
# between  two lanes of allowed bitrates. For out goals,
# the 'main' tier is more than enough and isn't outright rejected
# by cheap TVs.
#
if $tenBit ; then
	echo 10-bit encode
	ffmpegParameters+=(-pix_fmt yuv420p10le)
	svtParameters+=(-profile 2)
	svtParameters+=(-bit-depth 10)
else
	echo 8-bit encode
	ffmpegParameters+=(-pix_fmt yuv420p)
	svtParameters+=(-profile 1)
	svtParameters+=(-bit-depth 8)
fi

# ----------------------------------------------------------------------------

# Perform the actual transcode, letting ffmpeg output fullYUV frames into
# stdout, which is then piped into the SvtHevcEncApp executable
#
ffmpeg \
	-hide_banner \
	-i "$inputFile" \
	-nostdin \
	"${ffmpegParameters[@]}" \
	-f rawvideo \
	- | SvtHevcEncApp \
		-i stdin \
		-n $frameCount \
		-w $videoWidth \
		-h $videoHeight \
		-rc 1 \
		-tbr $videoBitRate \
		-fps-num $videoFrameRateNum \
		-fps-denom $videoFrameRateDenom \
		"${svtParameters[@]}" \
		-encMode 0 \
		-tier main \
		-b "$hevcFile"

# ----------------------------------------------------------------------------

# For some reason, the generated .hevc file, when merged via mkvmerge or
# mkvtoolnix, will not have the correct frame rate. This may be a bug in
# the mkv tools, but in either case, to fix it we just need to generate
# an .mkv file with correct frame rate and we're good...
#
mkvmergeParameters=()
mkvmergeParameters+=(--default-duration 0:${videoFrameRateNum}/${videoFrameRateDenom}fps)
mkvmergeParameters+=(--fix-bitstream-timing-information 0)
mkvmerge \
	"${mkvmergeParameters[@]}" \
	"$hevcFile" \
	-o "$outputFile"

# ----------------------------------------------------------------------------