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Useful Ffmpeg Filters |
5.5 |
Encoding Overview |
This is covering other things that can be done directly in ffmpeg that might be useful.
Table of contents
{: .text-delta } 1. TOC {:toc}- GOP values explained
- ffimprovisr is a great resource to find more friendly descriptions/examples of common ffmpeg use-cases.
-filter_complex "[1:0]apad" -shortest
This is a useful filter to add when adding an audio file, if the audio file might not match the length of the resulting movie. This will either pad the audio to match the video, if the audio is short, or truncate the audio to match the video.
TODO - Provide full example of adding audio to the "quickstart" demo.
There may be reasons that you want to do any image resizing directly inside ffmpeg, (e.g. when converting from another movie format). A number of the codecs require that the width and height be a factor of 2 (and sometimes 4). The expression below will ensure that the height is set correctly, assuming the width is 1920
-vf scale=1920:trunc(ow/a/2)*2:flags=lanczos
If you are downrezing, you will get the best results with the lancozs filter, otherwise the default is bicubic.
TODO - this needs testing, to confirm filter quality.
See: https://trac.ffmpeg.org/wiki/Scaling for more info.
See: https://trac.ffmpeg.org/wiki/Concatenate
This has been useful in splitting long prores encodes into chunks, and then merging them back together. The merge process is not quick, so there are limits to how much you can split the process, but provided that the merge process not I/O bound, it can typically end up with faster encodes.
TODO - Provide some examples of speed improvement, as well as a sample command line.
| | | | ffmpeg -formats | list all file formats | | ffmpeg -muxers | list all muxers (e.g. mp4, mov) | | ffmpeg -h muxer= | List of options for a particular muxer, e.g. ffmpeg -h muxer=mp4 | | ffmpeg -filters | list all filters | ffmpeg -codecs | list all codecs (encoders and decoders) | | ffmpeg -encoders | list just encoders | | ffmpeg -h encoder= | List args for specified encoder, e.g. ffmpeg -h encoder=prores_ks. This also lists what supported pixel formats are supported. | | ffmpeg -h decoder= | List args for specified decoder, e.g. ffmpeg -h decoder=exr |
Ffmpeg has a crazy number of filters (see Ffmpeg filters) below are some potentially relevant ones to VFX pipelines.
https://www.ffmpeg.org/ffmpeg-filters.html#toc-framepack - Generate a frame packed stereoscopic video
ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
https://www.ffmpeg.org/ffmpeg-filters.html#toc-stereo3d Re-pack an existing stereo movie into a different format
Creates a SMPTE HD colorbars image. NOTE, this is actually created in YUV space, and only for 8-bit Y'CrCb.
ffmpeg does have a built-in SMPTE color bars, however by default, it does not create it in the right colorspace, so you do need to specify the color primaries, colorspace and colortrc to make it behave correctly. Also note, these are 8-bit only.
This is an h264 output yuv422p
ffmpeg -re -color_primaries bt709 -colorspace bt709 -color_range tv -color_trc bt709 -f lavfi -i smptehdbars=duration=1:size=1920x1080:rate=1 -c:v h264 -crf 10 smptehdbars-h264.mov
This is a 8-bit 444 raw encode.
ffmpeg -re -color_primaries bt709 -colorspace bt709 -color_range tv -color_trc bt709 -f lavfi -i smptehdbars=duration=1:size=1920x1080:rate=1,format=yuv444p -c:v v408 smptehdbars-v408.mov
This is a PNG output, warning this would only be to the legal range, so the pluge would be zeroed out:
ffmpeg -color_primaries bt709 -colorspace bt709 -color_trc bt709 -re -f lavfi -i smptehdbars=duration=1:size=1920x1080:rate=1 -vframes 1 smptehdbars.png
Creates a Zoneplate test chart. This was introduced in ffmpeg 6.1 and is great for testing filtering.
Creating it with ffmpeg directly to RGB:
ffmpeg -f lavfi -i zoneplate=ku=512:kv=100:kt2=0:ky2=256:kx2=556:s=wvga:yo=0:kt=11:duration=1 -pix_fmt rgb48be zoneplate_rgb16.png
Creating it with ffmpeg directly to YCrCb:
ffmpeg -f lavfi -i zoneplate=ku=512:kv=100:kt2=0:ky2=256:kx2=556:s=wvga:yo=0:kt=11:duration=1 -pix_fmt yuv420p10 -strict -1 zoneplate_yuv420p10.y4m
A dummy source video signal.
Creating a blank YUV h264 file of 1024 frames.
ffmpeg -r 24 -f lavfi -i nullsrc=s=1280x720,format=yuv444p -frames:v 1024 yuv444p.mov
Creating a blank YUV 10-bit h264 file
ffmpeg -r 24 -f lavfi -i nullsrc=s=1280x720,format=yuv444p10le -frames:v 1024 yuv444p10le.mov
THis is commonly used with geq.
geq Apply a generic equation to each pixel
ffmpeg -r 24 -f lavfi -i nullsrc=s=512x512 -pix_fmt yuv444p -frames:v 1024 -vf geq=X/2:128:128 yuv444p_ramp.mov
If you want other bit-depths, you do need to add an additional format flag for example:
ffmpeg -r 24 -f lavfi -i nullsrc=s=1024x512,format=yuv444p10le -frames:v 1024 -vf geq=X:512:512 yuv444p10_ramp.mov
Calculate the differences between two image streams. toc-identity
ffmpeg -i movie1.mov -i movie2.mov -lavfi identity -f null -
Will output a line like:
identity Y:0.430940 U:0.516449 V:0.448389 average:0.465259 min:0.452062 max:0.480941``
Where each number is a 0-1 scale, where 1 is identical.
The two images need to be the same resolution and pixel format (at least both RGB or YCrCb).
Allows you to create a calculated LUT that is then applied to the picture.
Obtain the average, maximum and minimum PSNR (Peak Signal to Noise Ratio) between two input videos psnr
ffmpeg -i movie1.mov -i movie2.mov -lavfi psnr -f null -
Will output a line like:
PSNR y:46.121876 u:50.295497 v:48.852140 average:46.987439 min:45.790238 max:49.754820
Convert 360 videos between various formats. v360