Supported Video and Audio File Formats

Video and audio files in MATLAB^® and their supported file formats and codecs.

Video Data in MATLAB

What Are Video Files?

For video data, the term “file format” often refers to either the container format or the codec. A container format describes the layout of the file, while a codec describes how to encode/decode the video data. Many container formats can hold data encoded with different codecs.

To read a video file, any application must:

• Recognize the container format (such as AVI).

• Have access to the codec that can decode the video data stored in the file. Some codecs are part of standard Windows^® and Macintosh system installations, and allow you to play video in Windows Media^® Player or QuickTime^®. In MATLAB, VideoReader can access most, but not all, of these codecs.

• Properly use the codec to decode the video data in the file. VideoReader cannot always read files associated with codecs that were not part of your original system installation.

Formats That VideoReader Supports

Use VideoReader to read video files in MATLAB. The file formats that VideoReader supports vary by platform, and have no restrictions on file extensions.

Platforms	File Formats
All Platforms	AVI, including uncompressed, indexed, grayscale, and Motion JPEG-encoded video (.avi) Motion JPEG 2000 (.mj2) Note VideoReader does not support remote reading for formats exclusive to Microsoft® DirectShow®.
All Windows	MPEG-1 (.mpg) Windows Media Video (.wmv, .asf) Any format supported by Microsoft DirectShow
Windows 7 or later	MPEG-4, including H.264 encoded video (.mp4, .m4v) Apple QuickTime Movie (.mov) Any format supported by Microsoft Media Foundation
Macintosh	Most formats supported by QuickTime Player, including: MPEG-1 (.mpg) MPEG-4, including H.264 encoded video (.mp4, .m4v) Apple QuickTime Movie (.mov) 3GPP 3GPP2 AVCHD DV Note: For OS X Yosemite (Version 10.10) and later, MPEG-4/H.264 files written using VideoWriter, play correctly, but display an inexact frame rate.
Linux®	Any format supported by your installed plug-ins for GStreamer 1.0 or higher, as listed on https://gstreamer.freedesktop.org/documentation/plugins_doc.html, including Ogg Theora (.ogg).

View Codec Associated with Video File

This example shows how to view the codec associated with a video file, using the mmfileinfo function.

Store information about the sample video file, shuttle.avi, in a structure array named info. The info structure contains the following fields: Filename, Path, Duration, Audio and Video.

info = mmfileinfo('shuttle.avi');

Show the properties in the command window by displaying the fields of the info structure. For example, to view information under the Video field, type info.Video

info.Video

ans = struct with fields:
    Format: 'Motion JPEG'
    Height: 288
     Width: 512

The file, shuttle.avi, uses the Motion JPEG codec.

Troubleshooting: Errors Reading Video File

You might be unable to read a video file if MATLAB cannot access the appropriate codec. 64-bit applications use 64-bit codec libraries, while 32-bit applications use 32-bit codec libraries. For example, when working with 64-bit MATLAB, you cannot read video files that require access to a 32-bit codec installed on your system. To read these files, try one of the following:

• Install a 64-bit codec that supports this file format. Then, try reading the file using 64-bit MATLAB.

• Re-encode the file into a different format with a 64-bit codec that is installed on your computer.

Sometimes, VideoReader cannot open a video file for reading on Windows platforms. This might occur if you have installed a third-party codec that overrides your system settings. Uninstall the codec and try opening the video file in MATLAB again.

Audio Data in MATLAB

What Are Audio Files?

The audio signal in a file represents a series of samples that capture the amplitude of the sound over time. The sample rate is the number of discrete samples taken per second and given in hertz. The precision of the samples, measured by the bit depth (number of bits per sample), depends on the available audio hardware.

MATLAB audio functions read and store single-channel (mono) audio data in an m-by-1 column vector, and stereo data in an m-by-2 matrix. In either case, m is the number of samples. For stereo data, the first column contains the left channel, and the second column contains the right channel.

Typically, each sample is a double-precision value between -1 and 1. In some cases, particularly when the audio hardware does not support high bit depths, audio files store the values as 8-bit or 16-bit integers. The range of the sample values depends on the available number of bits. For example, samples stored as uint8 values can range from 0 to 255 (2⁸ – 1). The MATLAB sound and soundsc functions support only single- or double-precision values between -1 and 1. Other audio functions support multiple data types, as indicated on the function reference pages.

Formats That audioread Supports

Use audioread to read audio files in MATLAB. The audioread function supports these file formats.

Platform Support	File Format
All platforms	AIFC (.aifc)
	AIFF (.aiff, .aif)
	AU (.au)
	FLAC (.flac)
	OGG (.ogg)
	OPUS (.opus)
	WAVE (.wav)
Windows 7 (or later), Macintosh, and Linux	MP3 (.mp3)
	MPEG-4 AAC (.m4a, .mp4)

On Windows platforms prior to Windows 7, audioread does not read WAVE files with MP3 encoded data.

On Windows 7 (or later) platforms, audioread might also read any files supported by Windows Media Foundation.

On Linux platforms, audioread might also read any files supported by GStreamer.

audioread can extract audio from MPEG-4 (.mp4, .m4v) video files on Windows 7 or later, Macintosh, and Linux, and from Windows Media Video (.wmv) and AVI (.avi) files on Windows 7 (or later) and Linux platforms.