Mathematica package for using FFMPEG video library. This package accurately imports video frames into Mathematica. It is necessary for scientific applications as Mathematica's (v9 or v10) default methods uses QuickTime that produces artifact in uncompressed videos or duplicated frames. It also is useful for importing other video-codecs.
Mimicking Mathematica's Import function:
FFImport[ "file.avi", {"Frames", 1}] - gives first frame (slow way)
FFImport[ "file.avi", {"Frames", Range[1,1000]}] - gives first 1000 frames (fast)
Also supports some property look-up functions using ffprobe:
FFImport[ "file.avi", "FrameRate"] - returns the frame rate of the video
FFImport[ "file.avi", "Duration"] - returns the duration of the video in sec
FFImport[ "file.avi", "ImageSize"] - frame size in pixels
To test status of ffmpeg library you can run FFmpeg[].
You will need to add package via <<FFmpeg` if the package is in the path or via Import["FFmpeg.m"].
To install ffmpeg:
Using homebrew brew install ffmpeg
Untested at the moment. Must be accessible from terminal via command ffmpeg. Otherwise path can specified via FFmpeg["usr/bin/.../ffmpeg"].
If you are aiming for the best performance the package provides special tools for optimising your program. I achieved best performance when loading entire video with a single ffmpeg stream. In such case there is no need to go though the file multiple times. Three special functions are supplied: open stream with FFInputStreamAt, get frame with FFGetNextFrame or skip one FSkipFrame. See function docs for more info ?FFInputStreamAt. And don't forget to close the stream with Close[st] at the end.
Color mode can be changed via settings. Default one is "rgb24". If grey-scale is required, use:
Options[FFmpeg] = { "Colors" -> 1 (*number of color channels*), "ColorCommand" -> "gray" (*indicator for "-pix_fmt" parameter:gray/ rgb24*) };
- There is sometimes an error loading the video - where the ffmpeg reports end of stream before entire video was loaded. On the internet there seems to be a suggestion that stream is not closed properly in Mathematica. Be careful! In my experience it is a problem with external USB hard-drives. Copy it to permanent had drive fist.
- the fast lookup is not implemented. It is slow to go though large videos to the right frame. Load video in big lumps to avoid this penalty.
- There is no fast method for looking up frame number yet. Mathematica will report an estimate on this number but it might be inaccurate (typically difference is within few frames).
- Karolis Misiunas (github: kmisiunas)
- Kenta Takagaki (github: ktakagaki)