Video Encoding
Contents
Encoding in H.265
I've seen very good quality and significantly smaller file sizes in videos encoded with H.265.
ffmpeg -i infile.mp4 -c:v libx265 outfile.mp4
Deinterlacing
ffmpeg -i 000000.MTS -vf yadif -c:v libx265 outfile.mp4
Timelapse From Image Files
In the terminal, go into your folder full of images.
neuro@gamma:~/timelapse$ ls
DSC05145.JPG DSC05163.JPG DSC05181.JPG DSC05199.JPG DSC05217.JPG
DSC05146.JPG DSC05164.JPG DSC05182.JPG DSC05200.JPG DSC05218.JPG
DSC05147.JPG DSC05165.JPG DSC05183.JPG DSC05201.JPG DSC05219.JPG
DSC05148.JPG DSC05166.JPG DSC05184.JPG DSC05202.JPG DSC05220.JPG
...
Create a timelapse of all files, with a framerate of 20fps:
ffmpeg -r 20 -f image2 -pattern_type glob -i "*.JPG" -c:v libx265 ../out.mp4
Create a timelapse starting from file 05200, with a total of 30 frames:
ffmpeg -r 20 -f image2 -start_number 05200 -i DSC%05d.JPG -frames:v 30 -c:v libx265 ../out.mp4
Note: the "%05d" means zero-padded 5-digit number.
AV1 Codec Testing
Last updated 3/11/2020
AV1 is the newest emerging video coding format currently under development by AOMedia. I was interested in trying it out and seeing how it compares to my current favorite x265, and also the older x264. Keep in mind I'm doing this for my own purposes, so the following benchmarks are not comprehensive and are limited to my own intended use cases.
The AV! ligrary libaom-av1
is not currently available in ffmpeg by default. I found a good script someone made for compiling ffmpeg with support for AV1:
https://gist.github.com/sparrc/026ed9958502072dda749ba4e5879ee3
I downloaded the script:
wget https://gist.githubusercontent.com/sparrc/026ed9958502072dda749ba4e5879ee3/raw/e22698ead1984cd86b943f3473bd4bfb98591808/install-ffmpeg.sh
Note: as always, never download and run a script without reading it yourself to determine that it dos not do anything malicious.
I ran the script:
sudo bash install-ffmpeg.sh
this script installs the custom ffmpeg into ~/bin/ffmpeg
.
I chose a relatively small MTS file for testing:
du -h 00056.MTS
38M 00056.MTS
Runtime Benchmarks (Interlacing)
In the following benchmarks, the relevant time is the "real" time. The original test MTS file is encoded with video:h264, audio:ac3, and has interlacing. Each encoding process I do below uses all defaults for the format, and encodes the audio to aac.
x264 benchmark
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -c:v libx264 out_x264.mp4
real 0m28.159s user 1m43.388s sys 0m0.176s
x265 benchmark
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -c:v libx265 out_x265.mp4
real 0m43.420s user 2m40.852s sys 0m0.304s
av1 benchmark
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -c:v libaom-av1 -strict -2 out_av1.mp4
real 177m27.737s user 413m16.620s sys 0m6.688s
Note: The "-strict -2" parameter allows for the use of experimental codecs.
Conclusion
As you can see, the AV1 encoding took orders of magnitude longer.
- x264 = 28 seconds
- x265 = 43 seconds
- AV1 = 2 hours, 57 minutes, 27 seconds
Runtime Benchmarks (De-Interlacing)
In the following benchmarks, I decided to include de-interlacing.
x264 benchmark (de-interlacing)
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -vf yadif -c:v libx264 outd_x264.mp4
real 0m29.251s user 1m47.480s sys 0m0.260s
x265 benchmark (de-interlacing)
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -vf yadif -c:v libx265 outd_x265.mp4
real 0m42.207s user 2m34.120s sys 0m0.328s
av1 benchmark (de-interlacing)
time ~/bin/ffmpeg -loglevel -8 -i 00056.MTS -vf yadif -c:v libaom-av1 -strict -2 outd_av1.mp4
real 162m54.203s user 377m0.452s sys 0m4.940s
Conclusion
The times are not significantly different from my first test that included interlacing, but interestingly choosing to de-interlace marginally reduced the runtime in every test.
- x264 = 29 seconds
- x265 = 42 seconds
- AV1 = 2 hours, 42 minutes, 54 seconds
File Size Comparison
The files starting with out_
are interlaced, and outd_
are de-interlaced.
du -h out_*;du -h outd*
11M out_av1.mp4 15M out_x264.mp4 5.6M out_x265.mp4 8.2M outd_av1.mp4 13M outd_x264.mp4 4.1M outd_x265.mp4
Conclusion
The best codec for file size, by a pretty large margin, is still x265. De-interlacing also results in smaller file size for all codecs.
Video Quality Comparison
In this test, I will take a cropped portion of the same frame from each file so that I can visually compare them.
I used ffmpeg
to extract the 10th frame from each file:
for x in *.{MTS,mp4};do ffmpeg -i $x -vf "select=eq(n\,9)" -vframes 1 $x.png;done
Note: the "select" parameter takes a sequence starting at 0, so the 10th frame is 9.
I thought it was notable to look at the different in file size of the images:
du -h *.png
2.9M 00056.MTS.png 2.1M out_av1.mp4.png 2.0M outd_av1.mp4.png 2.4M outd_x264.mp4.png 2.1M outd_x265.mp4.png 2.4M out_x264.mp4.png 2.2M out_x265.mp4.png
I then cropped a portion of each image starting at pixels X=0,y=250 with a size of 500x300. To do this automatically, it used the Imagemagick convert
command:
for x in *.png;do convert $x -crop 500x300+0+250 ${x/\.png/_crop\.png};done