HEVC H.265
High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2, is a video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10). In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or substantially improved video quality at the same bit rate. It supports resolutions up to 8192×4320, including 8K UHD, and unlike the primarily 8-bit AVC, HEVC's higher fidelity Main 10 profile has been incorporated into nearly all supporting hardware. (Source: Wikipedia)
Command
To reduce the file size of an MKV video file and convert it to the H.265 (x265) codec using FFmpeg, you can use the following command:
ffmpeg -y -i input.mkv -c:v libx265 -hide_banner -loglevel info -preset fast -crf 23 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
- Documentation H265: https://trac.ffmpeg.org/wiki/Encode/H.265
- Documentation H264: https://trac.ffmpeg.org/wiki/Encode/H.264 (some options are same)
Here's what each part of the command does:
-y: This automatically overwrites the output file if it already exists.-i input.mkv: This specifies the input MKV file.-c:v libx265: This selects the H.265 (x265) video codec for compression.-hide_banner -loglevel info: This hides the FFmpeg banner and only shows the encoding progress. You can remove this if you want to see the banner and encoding information.-preset fast: This sets the x265 encoding preset to "fast," for encoding speed and compression efficiency. A slower preset will provide better compression (compression is quality per filesize). This means that, for example, if you target a certain file size or constant bit rate, you will achieve better quality with a slower preset.-crf 23: This sets the Constant Rate Factor (CRF), which determines the video quality. A lower value will result in higher quality but larger file size, and a higher value will reduce quality but result in a smaller file size. You can adjust this value to your desired trade-off between quality and size. Values range from 0 to 51, with 0 being lossless, 23 being the default, and 51 being the worst quality possible.-map 0:v:0: This selects the first video stream from the input file.-c:a aac -b:a 256k: This selects the AAC audio codec for compression and sets the audio bitrate to 256Kbps.-map 0:a: This selects all audio streams from the input file.-map 0:s?: This selects all subtitle streams from the input file, if any.output.mkv: This specifies the output file name.
After running this command, FFmpeg will encode the input MKV file using the x265 codec with the specified settings, resulting in a smaller MKV file size while retaining acceptable video and audio quality.
Reduce file size
To reduce file size, you can change crf value to 28 or 30, but the quality will be lower.
The range of the CRF scale is 0–51, where 0 is lossless (for 8 bit only, for 10 bit use -qp 0), 23 is the default, and 51 is worst quality possible. A lower value generally leads to higher quality, and a subjectively sane range is 17–28. Consider 17 or 18 to be visually lossless or nearly so; it should look the same or nearly the same as the input but it isn't technically lossless.
The range is exponential, so increasing the CRF value +6 results in roughly half the bitrate / file size, while -6 leads to roughly twice the bitrate.
Choose the highest CRF value that still provides an acceptable quality. If the output looks good, then try a higher value. If it looks bad, choose a lower value.
Accelerate encoding
To accelerate encoding, you can change preset value to ultrafast, but the file size will be bigger.
A preset is a collection of options that will provide a certain encoding speed to compression ratio. A slower preset will provide better compression (compression is quality per filesize). This means that, for example, if you target a certain file size or constant bit rate, you will achieve better quality with a slower preset. Similarly, for constant quality encoding, you will simply save bitrate by choosing a slower preset.
Use the slowest preset that you have patience for. The available presets in descending order of speed are:
ultrafastsuperfastveryfastfasterfastmedium– default presetslowslowerveryslowplacebo– ignore this as it is not useful (see FAQ)
You can see a list of current presets with -preset help.
Tune
You can optionally use -tune to change settings based upon the specifics of your input. Current tunings include:
film– use for high quality movie content; lowers deblockinganimation– good for cartoons; uses higher deblocking and more reference framesgrain– preserves the grain structure in old, grainy film materialstillimage– good for slideshow-like contentfastdecode– allows faster decoding by disabling certain filterszerolatency– good for fast encoding and low-latency streamingpsnr– ignore this as it is only used for codec developmentssim– ignore this as it is only used for codec development
For example, if your input is animation then use the animation tuning, or if you want to preserve grain in a film then use the grain tuning. If you are unsure of what to use or your input does not match any of tunings then omit the -tune option. You can see a list of current tunings with -tune help.
Scripts
To automate the process, you can use a script.
Bash Script
Create hevc.sh file
#!/bin/bash
# Get the video file
video="$1"
presetValue="fast"
crfValue="23"
tuneValue=""
while [[ $# -gt 0 ]]; do
case "$1" in
-p|--preset)
flag1="$2"
shift 2
;;
-c|--crf)
flag2="$2"
shift 2
;;
-t|--tune)
flag3="$2"
shift 2
;;
*)
echo "Unknown flag: $1"
exit 1
;;
esac
done
# Get filename
filename=$(basename -- "$video")
# Get extension
extension="${filename##*.}"
filename="${filename%.*}"
# Output
output="${filename}_output.$extension"
echo "Filename: $filename"
echo "Extension: $extension"
echo "Output: $output"
echo "Preset: $presetValue"
echo "CRF: $crfValue"
echo "Tune: $tuneValue"
baseCommand="ffmpeg -y -i '$video' -c:v libx265"
hideBanner="-hide_banner -loglevel info"
preset="-preset $presetValue"
crf="-crf $crfValue"
audio="-map 0:a -c:a aac -b:a 256k"
subtitle="-map 0:s? -c:s copy"
output="-map 0:v:0 '$output'"
if [ -n "$tuneValue" ]; then
tune="-tune $tuneValue"
command="$baseCommand $hideBanner $preset $crf $tune $audio $subtitle $output"
else
command="$baseCommand $hideBanner $preset $crf $audio $subtitle $output"
fi
start=$(date)
# FFmpeg command
echo "Command: $command"
eval "$command"
end=$(date)
echo "Start: $start"
echo "End: $end"
Usage
./hevc.sh "input.mkv"
And with options
./hevc.sh "input.mkv" -p medium -c 28 -t animation
Bash script with loop
#!/bin/bash
presetValue="fast"
crfValue="23"
tuneValue=""
while [[ $# -gt 0 ]]; do
case "$1" in
-p|--preset)
flag1="$2"
shift 2
;;
-c|--crf)
flag2="$2"
shift 2
;;
-t|--tune)
flag3="$2"
shift 2
;;
*)
echo "Unknown flag: $1"
exit 1
;;
esac
done
function hevc {
# Get filename
filename=$(basename -- "$video")
# Get extension
extension="${filename##*.}"
filename="${filename%.*}"
# Output
output="${filename}_output.$extension"
echo "Filename: $filename"
echo "Extension: $extension"
echo "Output: $output"
echo "Preset: $presetValue"
echo "CRF: $crfValue"
echo "Tune: $tuneValue"
baseCommand="ffmpeg -y -i '$video' -c:v libx265"
hideBanner="-hide_banner -loglevel info"
preset="-preset $presetValue"
crf="-crf $crfValue"
audio="-map 0:a -c:a aac -b:a 256k"
subtitle="-map 0:s? -c:s copy"
output="-map 0:v:0 '$output'"
if [ -n "$tuneValue" ]; then
tune="-tune $tuneValue"
command="$baseCommand $hideBanner $preset $crf $tune $audio $subtitle $output"
else
command="$baseCommand $hideBanner $preset $crf $audio $subtitle $output"
fi
start=$(date)
# FFmpeg command
echo "Command: $command"
eval "$command"
end=$(date)
echo "Start: $start"
echo "End: $end"
}
# Loop through all .mkv files in the current directory
for file in *.mkv; do
[ -f "$file" ] || continue # Skip if not a regular file
# if filename contains "output" then skip
[[ $file == *"output"* ]] && continue
hevc "$file"
done
Usage, with all .mkv files in the current directory. You can add options at the end of the command.
./hevc-loop.sh
PowerShell Script
Create hevc.ps1 file
# Get the video file
$video = $args[0]
$presetValue = "fast"
$crfValue = "23"
$tuneValue = $null
for ($i = 0; $i -lt $args.Length; $i++) {
$arg = $args[$i]
if ($arg -eq "-preset" -and $i + 1 -lt $args.Length) {
$presetValue = $args[$i + 1]
$i++
}
elseif ($arg -eq "-crf" -and $i + 1 -lt $args.Length) {
$crfValue = $args[$i + 1]
$i++
}
elseif ($arg -eq "-tune" -and $i + 1 -lt $args.Length) {
$tuneValue = $args[$i + 1]
$i++
}
else {
Write-Host "Unknown argument: $arg"
}
}
# get filename
$filename = [System.IO.Path]::GetFileNameWithoutExtension($video)
# get extension
$extension = [System.IO.Path]::GetExtension($video)
# output
$output = $filename + "_output" + $extension
Write-Host "Filename: $filename"
Write-Host "Extension: $extension"
Write-Host "Output: $output"
Write-Host "Preset: $presetValue"
Write-Host "CRF: $crfValue"
Write-Host "Tune: $tuneValue"
$baseCommand = "ffmpeg -y -i $video -c:v libx265"
$hideBanner = "-hide_banner -loglevel info"
$preset = "-preset $presetValue"
$crf = "-crf $crfValue"
$audio = "-map 0:a -c:a aac -b:a 256k"
$subtitle = "-map 0:s? -c:s copy"
$output = "-map 0:v:0 $output"
if ($tuneValue -ne $null) {
$tune = "-tune $tuneValue"
$command = "$baseCommand $hideBanner $preset $crf $tune $audio $subtitle $output"
}
else {
$command = "$baseCommand $hideBanner $preset $crf $audio $subtitle $output"
}
$start = Get-Date
# ffmpeg command
Write-Host "Command: $command"
Invoke-Expression $command
$end = Get-Date
Write-Host "Start: $start"
Write-Host "End: $end"
Usage
.\hevc.ps1 "input.mkv"
And with options
.\hevc.ps1 "input.mkv" -preset medium -crf 28 -tune animation
PowerShell script with loop
$presetValue = "fast"
$crfValue = "23"
$tuneValue = $null
for ($i = 0; $i -lt $args.Length; $i++) {
$arg = $args[$i]
if ($arg -eq "-preset" -and $i + 1 -lt $args.Length) {
$presetValue = $args[$i + 1]
$i++
}
elseif ($arg -eq "-crf" -and $i + 1 -lt $args.Length) {
$crfValue = $args[$i + 1]
$i++
}
elseif ($arg -eq "-tune" -and $i + 1 -lt $args.Length) {
$tuneValue = $args[$i + 1]
$i++
}
else {
Write-Host "Unknown argument: $arg"
}
}
function hevc($video) {
# get filename
$filename = [System.IO.Path]::GetFileNameWithoutExtension($video)
# get extension
$extension = [System.IO.Path]::GetExtension($video)
# output
$output = $filename + "_output" + $extension
Write-Host "Filename: $filename"
Write-Host "Extension: $extension"
Write-Host "Output: $output"
Write-Host "Preset: $presetValue"
Write-Host "CRF: $crfValue"
Write-Host "Tune: $tuneValue"
$baseCommand = "ffmpeg -y -i $video -c:v libx265"
$hideBanner = "-hide_banner -loglevel info"
$preset = "-preset $presetValue"
$crf = "-crf $crfValue"
$audio = "-map 0:a -c:a aac -b:a 256k"
$subtitle = "-map 0:s? -c:s copy"
$output = "-map 0:v:0 $output"
if ($tuneValue -ne $null) {
$tune = "-tune $tuneValue"
$command = "$baseCommand $hideBanner $preset $crf $tune $audio $subtitle $output"
}
else {
$command = "$baseCommand $hideBanner $preset $crf $audio $subtitle $output"
}
$start = Get-Date
# ffmpeg command
Write-Host "Command: $command"
Invoke-Expression $command
$end = Get-Date
Write-Host "Start: $start"
Write-Host "End: $end"
}
$mkvFiles = Get-ChildItem -Path . -Filter *.mkv
# Loop through each .mkv file
foreach ($file in $mkvFiles) {
# if filename contains "output" then skip
if ($file.Name.Contains("output")) {
continue
}
hevc($file)
}
Usage, with all .mkv files in the current directory. You can add options at the end of the command.
.\hevc-loop.ps1
Testing
output.1
ffmpeg -i input.mkv -c:v libx265 -crf 23 -preset medium -c:a aac -strict experimental -b:a 128k -scodec copy -acodec copy output.mkv
No full audio tracks
output.2
ffmpeg -i input.mkv -c:v libx265 -crf 23 -preset medium -c:a aac -strict experimental -b:a 128k -map 0 output.mkv
Audio tracks compressed
output.3
ffmpeg -i input.mkv -c:v libx265 -crf 23 -preset medium -c:a aac -strict experimental -b:a 128k -map 0:v:0 output.mkv
No audio tracks
output.4
ffmpeg -i input.mkv -map 0:v -map 0:a -c:v libx265 -preset medium -crf 23 -c:a copy output.mkv
Full audio tracks, double video tracks, no subtitles
output.5
ffmpeg -i input.mkv -map 0:v -map 0:a -map 0:s? -c:v libx265 -preset medium -crf 23 -c:a copy output.mkv
Double video tracks
output.6
ffmpeg -i input.mkv -map 0:a -map 0:s? -c:v libx265 -preset slow -crf 23 -c:a aac -strict experimental -b:a 128k output.mkv
No video track
output.7
ffmpeg -i input.mkv -map 0:v -map 0:a -map 0:s? -c:v libx265 -preset slow -crf 23 -c:a aac -strict experimental -b:a 128k output.mkv
Double video tracks
output.8
ffmpeg -i input.mkv -c:v libx265 -preset slow -crf 23 -map 0:v:0 -map 0:a -map 0:s? -c:s copy output.mkv
Sound bad quality
output.9
ffmpeg -i input.mkv -c:v libx265 -preset slow -crf 18 -map 0:v:0 -map 0:a -map 0:s? -c:s copy output.mkv
output.10
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 18 -map 0:v:0 -map 0:a -map 0:s? -c:s copy -c:a aac -strict experimental -b:a 128k output.mkv
Excellent but audio track quality
output.11
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 18 -map 0:v:0 -c:a aac -b:a 192k -map 0:a -map 0:s? -c:s copy output.mkv
Excellent
output.12
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 18 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
No change
output.13
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 23 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
Smallest file
output.14
ffmpeg -i input.mkv -c:v libx265 -preset slow -crf 23 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
2 hours, no changes, bitrate=1000kbits/s, speed=0.5x
output.15
ffmpeg -i input.mkv -c:v libx265 -preset medium -crf 23 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
50 min average,bitrate=1000kbits/s, speed=1.7x
output.16
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 23 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
40 min average,bitrate=1000kbits/s, speed=2.5x
output.17
ffmpeg -i input.mkv -c:v libx265 -preset fast -crf 18 -map 0:v:0 -c:a aac -b:a 256k -map 0:a -map 0:s? -c:s copy output.mkv
45 min average,bitrate=1000kbits/s, speed=2x, big file size
Files list
-a---- 10/5/2023 4:59 PM 2256732642 input.mkv
-a---- 9/30/2023 11:10 AM 1221852163 output.1.mkv
-a---- 10/7/2023 2:19 PM 1996117608 output.10.mkv
-a---- 10/7/2023 4:01 PM 2119373597 output.11.mkv
-a---- 10/7/2023 5:40 PM 2240962297 output.12.mkv
-a---- 10/7/2023 7:27 PM 1058118929 output.13.mkv
-a---- 10/29/2023 4:12 PM 1137133039 output.14.mkv
-a---- 10/30/2023 2:05 PM 1057563589 output.15.mkv
-a---- 10/30/2023 3:01 PM 1058118929 output.16.mkv
-a---- 10/30/2023 3:55 PM 2240962297 output.17.mkv
-a---- 10/5/2023 6:54 PM 1101583708 output.2.mkv
-a---- 10/5/2023 7:49 PM 933282959 output.3.mkv
-a---- 10/5/2023 8:37 PM 1068343912 output.4.mkv
-a---- 10/6/2023 1:32 PM 1068474913 output.5.mkv
-a---- 10/6/2023 2:11 PM 168340102 output.6.mkv
-a---- 10/6/2023 5:17 PM 1031536640 output.7.mkv
-a---- 10/6/2023 7:36 PM 1110082552 output.8.mkv
-a---- 10/6/2023 10:00 PM 2104754176 output.9-stopped.mkv