vlc-matlab

Thin, limited Matlab wrapper for libvlc to do fast video playback

What is this?

I needed real time video playback, synchronized with other data visualization happening in Matlab at the same time. In all my experiments, Matlab really sucks at real time video playback. Even opening the video file takes a prohibitively long time, and then you can only plod along drawing one... frame... at... a... time. Synchronously. Meanwhile, I noticed that VLC is available on nearly every platform and is great at real-time video playback. I decided that rather than try to reinvent the wheel in Matlab, I should just try to glue on VLC's existing wheel. This wrapper does that.

Where does it work?

The wrapper has been tested and works on at least these platforms:

• Linux (Ubuntu 12.04)
• Mac OS X (10.9.5)
• Windows 7, 8

Software dependencies are (obviously) Matlab and VLC:

• Matlab (tested on versions 2014a and 2014b)
• VLC (tested using versions 2.1.5 and 2.2.1)

What can the wrapper do?

The functionality is very limited. You can get a handle to a VLC object. Armed with this handle, you can open a video file (which returns another handle to the media). A window is automatically created. With the media handle you can get basic information (frame rate and length), play and pause the media, seek to a specific point, or query the current position.

That's it! I wrapped the functions I needed and no more. Feature requests (or pull requests!) welcome if you need more features.

Planned features

• Matlab facility for adaptively synchronizing a timer with the video
• (Windows) Depend on already-installed VLC instead of bundling DLLs

Installation

Download the latest release from here and extract it somewhere. You'll want to add the extracted folder to your Matlab path.

Linux

1. Install Matlab. Edit build_linux.sh (see comments there) to set the path to Matlab.
2. Install VLC with development headers (for example, on Debian/Ubuntu sudo apt-get install libvlc-dev).
3. Run the build script: ./build_linux.sh.

Mac

1. Install Matlab. Edit build_mac.sh (see comments there) to set the path to Matlab.
2. Install VLC. Edit build_mac.sh (see comments there) to set the path to VLC.
3. Run the build script: ./build_mac.sh.

Windows

1. Install Matlab.
2. Run the build script: build_windows.bat.

Example

This Matlab example creates the VLC instance, loads a video file, plays it for a bit, then queries the frame count of where it stopped. The "cleanup" command closes the window and releases the handles.

>> vlc_setup
>> vh = vlc_wrapper('init')
vh =
  6.9432e-310
>> vp = vlc_wrapper('open', vh, 'movie.avi')
vp =
  6.9432e-310
>> vlc_wrapper('play', vp, 1.0) % change 1.0 to 0.5 for slow-mo
>> vlc_wrapper('pause', vp)
>> vlc_wrapper('frame', vp)
ans =
  6678
>> vlc_wrapper cleanup

Note that the handles are returned as numbers, but they are to be treated as opaque objects! There is some crash protection -- if you pass a nonexistent file path or an invalid handle, the wrapper will refuse to do anything instead of freezing Matlab (hopefully).