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date: 2024-01-04 19:25:21
categories: linux
firstPublishDate: 2022-05-25 07:54:25
I don't encode many videos but I want to try the newest video and audio codecs:
AV1 is implemented in libaom and svt-av1. Libaom is the reference codec, it produces smaller files than svt-av1 but it is slow. The svt-av1 encoder is optimized for speed and produces bigger files than libaom.
I usually encode videos in 2 passes, libaom uses my 16 cores at 33% in pass 1 while svt-av1 uses the 16 cores at 100%. In pass 2, libaom uses 2 cores at 100% and svt1-av1 uses the 16 cores at 100%.
I encode my videos with libaom to get smaller files for a given quality because it takes a finite time to encode and I will store the videos forever.
I film with my iPhone in 4k 60 fps hevc and I don't have a computer that can play these videos so I also scale down the resolution.
Encoding the iPhone videos in h264 (using the parameters below) make them 20 times smaller, I transfer back to the videos to iPhone to save space and avoid having to use iCloud.
I installed FFmpeg and libaom from apt but I don't recommend doing this because it is better to use the latest AV1 encoders.
apt-get install ffmpeg libaom0 libaom-dev nasm yasm libx264-dev libx265-dev libnuma-dev libfdk-aac-dev libopus-dev libass-dev libdav1d-dev libmp3lame-dev libvorbis-dev libvpx-dev
Instead, I compile FFmpeg from source:
git clone --depth 1 https://aomedia.googlesource.com/aom commit ef14518388c0a41c1d3b992f75d5886c9da33832 mk build cmake -G "Unix Makefiles" -DENABLE_TESTS=OFF -DENABLE_NASM=on ../ make -j30 sudo make install git clone --depth=1 https://gitlab.com/AOMediaCodec/SVT-AV1.git commit 8c2621f75a5d6bc4b719b46fb6b17701a6f3fe1d cd SVT-AV1 cd Build cmake .. -G"Unix Makefiles" -DCMAKE_BUILD_TYPE=Release make -j 30 sudo make install git clone https://git.ffmpeg.org/ffmpeg.git commit f1c19867d72a14699277175101b2bcf1e333af88 ./configure \ --pkg-config-flags="--static" \ --extra-libs="-lpthread -lm" \ --ld="g++" \ --bindir="$HOME/bin" \ --enable-gpl \ --enable-libaom \ --enable-libass \ --enable-libfdk-aac \ --enable-libfreetype \ --enable-libmp3lame \ --enable-libopus \ --enable-libdav1d \ --enable-libvorbis \ --enable-libvpx \ --enable-libx264 \ --enable-libx265 \ --enable-nonfree make -j30
To show the information about a video file, use `ffprobe`:
ffprobe filename
# ffprobe prints stderr, redirect to be able to grep
ffprobe filename 2>&1 | grep displaymatrix
# result
ffprobe version N-106826-gf1c19867d7 Copyright (c) 2007-2022 the FFmpeg developers
built with gcc 10 (Debian 10.2.1-6)
configuration: --pkg-config-flags=--static --extra-libs='-lpthread -lm' --ld=g++ --bindir=/home/user/bin --enable-gpl --enable-libaom --enable-libsvtav1 --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libdav1d --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
libavutil 57. 24.101 / 57. 24.101
libavcodec 59. 27.100 / 59. 27.100
libavformat 59. 23.100 / 59. 23.100
libavdevice 59. 6.100 / 59. 6.100
libavfilter 8. 38.100 / 8. 38.100
libswscale 6. 6.100 / 6. 6.100
libswresample 4. 6.100 / 4. 6.100
libpostproc 56. 5.100 / 56. 5.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/user/AIphoneUpload/IMG_1819.MOV':
Metadata:
major_brand : qt
minor_version : 0
compatible_brands: qt
creation_time : 2022-11-18T17:37:37.000000Z
com.apple.quicktime.location.accuracy.horizontal: 35.000000
com.apple.quicktime.location.ISO6709: +55.7093+013.2177+065.187/
com.apple.quicktime.make: Apple
com.apple.quicktime.model: iPhone 12 Pro Max
com.apple.quicktime.software: 15.7.1
com.apple.quicktime.creationdate: 2022-11-18T18:37:36+0100
Duration: 00:00:24.59, start: 0.000000, bitrate: 67647 kb/s
Stream #0:0[0x1](und): Video: hevc (Main 10) (hvc1 / 0x31637668), yuv420p10le(tv, bt2020nc/bt2020/arib-std-b67), 3840x2160, 67375 kb/s, 59.99 fps, 60 tbr, 600 tbn (default)
Metadata:
creation_time : 2022-11-18T17:37:37.000000Z
handler_name : Core Media Video
vendor_id : [0][0][0][0]
encoder : HEVC
Side data:
DOVI configuration record: version: 1.0, profile: 8, level: 10, rpu flag: 1, el flag: 0, bl flag: 1, compatibility id: 4
displaymatrix: rotation of -90.00 degrees
Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 159 kb/s (default)
Metadata:
creation_time : 2022-11-18T17:37:37.000000Z
handler_name : Core Media Audio
vendor_id : [0][0][0][0]
Stream #0:2[0x3](und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
Metadata:
creation_time : 2022-11-18T17:37:37.000000Z
handler_name : Core Media Metadata
Stream #0:3[0x4](und): Data: none (mebx / 0x7862656D), 11 kb/s (default)
Metadata:
creation_time : 2022-11-18T17:37:37.000000Z
handler_name : Core Media Metadata
Stream #0:4[0x5](und): Data: none (mebx / 0x7862656D), 72 kb/s (default)
Metadata:
creation_time : 2022-11-18T17:37:37.000000Z
handler_name : Core Media Metadata
The important line in the ffprobe output is:
displaymatrix: rotation of -90.00 degrees
It tells me if I should rotate the video.
For DVD resolution (720x576), I use a bitrate of 650kb/s
For 4k fps 60 resolution, I use a bitrate of 2mb/s, the quality seems correct but I can't really check because it takes 15s to decode a frame.
It is quite slow to encode with libaom:
for 1s of UHD 60fps video, it takes about 1 hour.
for 1s of HD video, it takes 10 minutes
for 1s of DVD video, it takes 2 minutes
The SVT-AV1 encoder is 300 times faster than libaom-av1.
For more information about the encoding option for AV1 in FFmpeg, check out:
The setup of svt-av1 is not perfect, I get this error:
ffmpeg: error while loading shared libraries: libSvtAv1Enc.so.1: cannot open shared object file: No such file or directory
In order to find libsvtav1, update LD_LIBRARY_PATH:
export LD_LIBRARY_PATH+=":/usr/local/lib" # run ffmpeg
I encode videos with 2 pass in order to improve the image quality.
I created a test video file by cutting 10s of a DVD with FFmpeg:
ffmpeg -i example.VOB -ss 00:10:00 -to 00:10:30 -c copy y.VOB
To encode with libaom:
ffmpeg -i y.VOB -c:v libaom-av1 -b:v 650k -pass 1 -an -f null /dev/null && \ ffmpeg -i y.VOB -c:v libaom-av1 -b:v 650k -pass 2 -ac 2 -c:a libopus y.mkv
To encode with svt1av1:
ffmpeg -i y.VOB -c:v libsvtav1 -b:v 650k -pass 1 -an -f null /dev/null && \ ffmpeg -i y.VOB -c:v libsvtav1 -b:v 650k -pass 2 -ac 2 -c:a libopus y.mkv
I encountered an error encoding a DVD with audio in AC3 5.1 and libopus:
[libopus @ 0x55896ce87c80] Invalid channel layout 5.1(side) for specified mapping family -1. Error initializing output stream 0:1 -- Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height
To solve this, I add the `-ac 2` option to have the output in 2 streams (stereo).
To encode with libaom:
ffmpeg -i IMG_1454.MOV -c:v libaom-av1 -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1454.MOV -c:v libaom-av1 -b:v 2000k -pass 2 -ac 2 -c:a libopus y.mkv
To encode with svtav1:
ffmpeg -i IMG_1454.MOV -c:v libsvtav1 -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1454.MOV -c:v libsvtav1 -b:v 2000k -pass 2 -ac 2 -c:a libopus y.mkv
The option for scaling the video is `-vf scale=`:
ffmpeg -i IMG_1454.MOV -vf scale=720:576 -c:v libsvtav1 -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1454.MOV -vf scale=720:576 -c:v libsvtav1 -b:v 2000k -pass 2 -ac 2 -c:a libopus y.mkv
When the video is vertical as indicated by `displaymatrix: rotation of -90.00 degrees`, I encode video with these parameters (540:960 instead of 960:540 for horizontal videos):
ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libsvtav1 -b:v 1000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libsvtav1 -b:v 1000k -pass 2 -ac 2 -c:a libopus IMG_1819.mkv
ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libx264 -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libx264 -b:v 2000k -pass 2 -ac 2 -c:a libopus IMG_1819.mkv
To be able to play video directly in all web browsers additional parameters are needed `-profile:v main -pix_fmt yuv420p` and for audio `-c:a aac -ac 2 -strict experimental -b:a 128k`, the commands become:
ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libx264 -profile:v main -pix_fmt yuv420p -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1819.MOV -vf scale=540:960 -c:v libx264 -profile:v main -pix_fmt yuv420p -b:v 2000k -pass 2 -c:a aac -ac 2 -strict experimental -b:a 128k IMG_1819.mkv
The parameters in previous section don't allow playing the video in all operating systems. With the configuration below, the video files are playable directly from the web page on Linux, MacOS and Windows and in all major browsers: firefox, safari, chrome, edge.
ffmpeg -i IMG_1819.MOV -vf "fps=30,scale=960x540" -c:v libx264 -profile:v main -pix_fmt yuv420p -b:v 2000k -pass 1 -an -f null /dev/null && \ ffmpeg -i IMG_1819.MOV -vf "fps=30,scale=960x540" -c:v libx264 -profile:v main -pix_fmt yuv420p -b:v 2000k -pass 2 -c:a aac -ac 2 -strict experimental -b:a 128k IMG_1819.mp4
I have a
in a thinkpad from 2003. To be able to watch videos on this computer, I need to:
scale to 480x270
encode in mpeg2
change framerate from 60fps to 30fps
encode audio in mp3
ffmpeg -i IMG_1819.MOV -vf "fps=30,scale=270x480" -c:v mpeg2video -b:v 3000k -c:a libmp3lame IMG_1819.mkv
The resulting file is 1GB for 1h30 of video with reasonable quality.
With ffmpeg, it is possible to cut a long video and make shorter clip, with this command:
ffmpeg -i "video.mp4" -ss 00:03:00 -c copy -to 00:03:03 clip.mp4
ffmpeg -i video_file -i audio_file -c:v copy -c:a copy out_file.mp4
hashtags: #ffmpeg #video #encoding
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