#5854 closed defect (invalid)
H.264 encoding - veryfast preset produces smaller file than faster preset
Reported by: | mimac | Owned by: | |
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Priority: | normal | Component: | undetermined |
Version: | git-master | Keywords: | |
Cc: | Blocked By: | ||
Blocking: | Reproduced by developer: | no | |
Analyzed by developer: | no |
Description
Summary of the bug:
According to https://trac.ffmpeg.org/wiki/Encode/H.264, for constant quality encoding, faster preset should be slower and produce smaller file than veryfast preset. However, by my testing, faster preset produced always bigger file than veryfast preset.
How to reproduce:
ffmpeg version N-81696-gd38dff8e-static http://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2016 the FFmpeg developers built with gcc 5.4.1 (Debian 5.4.1-2) 20160904 configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-libwebp --enable-libspeex --enable-libvorbis --enable-libvpx --enable-libfreetype --enable-fontconfig --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-amrwbenc --enable-gray --enable-libopenjpeg --enable-libopus --enable-libass --enable-gnutls --enable-libvidstab --enable-libsoxr --enable-frei0r --enable-libfribidi --disable-indev=sndio --disable-outdev=sndio --enable-librtmp --enable-libmfx --enable-libzimg --cc=gcc-5 libavutil 55. 29.100 / 55. 29.100 libavcodec 57. 57.100 / 57. 57.100 libavformat 57. 49.100 / 57. 49.100 libavdevice 57. 0.102 / 57. 0.102 libavfilter 6. 62.100 / 6. 62.100 libswscale 4. 1.100 / 4. 1.100 libswresample 2. 1.100 / 2. 1.100 libpostproc 54. 0.100 / 54. 0.100 % ffmpeg -i newmobcal1920_12mbps.ts -c:v libx264 -profile:v high -level 4.0 -preset faster result-faster.mkv % ffmpeg -i newmobcal1920_12mbps.ts -c:v libx264 -profile:v high -level 4.0 -preset veryfast result-veryfast.mkv % ll *.mkv -rw-rw-r-- 1 user user 84785654 Sep 19 21:28 result-faster.mkv -rw-rw-r-- 1 user user 77822551 Sep 19 21:15 result-veryfast.mkv
Input video is from http://www.w6rz.net (http://www.w6rz.net/newmobcal1920_12mbps.ts). Reports are attached.
I was able to reproduce this behavior on Ubuntu as well as Windows, with three different input files (H.264, MPEG2, MJPEG), also with CFR values 18, 23 and 28. Veryfast preset always produced smaller file than faster and fast preset, in most cases also smaller than medium preset.
Attachments (2)
Change History (6)
by , 8 years ago
Attachment: | ffmpeg-20160919-213026-faster.log added |
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comment:1 by , 8 years ago
Version: | unspecified → git-master |
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comment:2 by , 8 years ago
Resolution: | → invalid |
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Status: | new → closed |
First and foremost, these are libx264 presets and not something FFmpeg manages. As such, any questions to how libx264 compression works should be directed to that project.
To the issue at hand, there are no size guarantees for any of the presets, only speed/quality tradeoffs. It is very well possible that faster presets produce smaller files, albeit at a lower quality.
comment:3 by , 8 years ago
I will direct the question to libx264 project, sorry for misunderstanding.
For the size guarantees, I made tests with constant quality settings and thought that results would comply with what page about encoding states:
Similarly, for constant quality encoding, you will simply save bitrate by choosing a slower preset.
comment:4 by , 8 years ago
Keywords: | H.264 preset removed |
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Report for faster preset