To Multimedia File

Stream video frames and audio samples to multimedia file

• 

Libraries:
Audio System Toolbox / Sinks
DSP System Toolbox / Sinks

Description

The To Multimedia File block writes video frames, audio samples, or both to a multimedia (.avi, .wav, .wma, .mp4, .ogg, .flac, .wmv) file.

You can compress the video frames or audio samples by selecting a compression algorithm. You can connect as many of the input ports as you want. Therefore, you can control the type of video and/or audio the multimedia file receives.

Note

This block supports code generation for platforms that have file I/O available. You cannot use this block with Simulink^® Desktop Real-Time™ software, because that product does not support file I/O.

This block performs best on platforms with Version 11 or later of Windows Media^® Player software. This block supports only uncompressed RGB24 AVI files on Linux^® and Mac platforms.

Windows^® 7 UAC (User Account Control) might require administrative privileges to encode WMV and WMA files.

The generated code for this block relies on prebuilt library files. You can run this code outside the MATLAB^® environment or redeploy it, but be sure to account for these extra library files when doing so. The packNGo function creates a single zip file containing all of the pieces required to run or rebuild this code. See packNGo (Simulink Coder) for more information.

To run an executable file that was generated from a model containing this block, you may need to add precompiled shared library files to your system path. See Understanding C Code Generation in DSP System Toolbox for details.

Examples

Sample Rate Conversion of Audio Signal

Convert the sample rate of the input audio signal.

• Open Model

Ports

For the block to display video data properly, double- and single-precision floating-point pixel values must be between 0 and 1. Any other data type requires the pixel values between the minimum and maximum values supported by their data type.

Check the specific codecs you are using for supported audio rates.

Input

Image — Color image or video frame

array

Specify the color image or video frame as an M-by-N-by-3 matrix RGB, Intensity, or YCbCr 4:2:2 signal. M and N are the number of rows and columns in each image.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to RGB and Image signal parameter to One multidimensional signal.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

R — Red color component of image or video frame

matrix

Specify the red color component of the image or video frame as an M-by-N matrix. M and N are the number of rows and columns in the image.

Inputs to the R, G, or B ports must have the same dimensions.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to RGB and Image signal parameter to Separate color signals.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

G — Green color component of image or video frame

matrix

Specify the green color component of the image or video frame as an M-by-N matrix. M and N are the number of rows and columns in the image.

Inputs to the R, G, or B ports must have the same dimensions.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to RGB and Image signal parameter to Separate color signals.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

B — Blue color component of image or video frame

matrix

Specify the blue color component of the image or video frame as an M-by-N matrix. M and N are the number of rows and columns in the image.

Inputs to the R, G, or B ports must have the same dimensions.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to RGB and Image signal parameter to Separate color signals.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Y — Luma component of image or video frame

matrix

Specify the luma component of the image or video frame as an M-by-N matrix. M and N are the number of rows and columns in the image.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to YCbCr 4:2:2.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Cb — Blue-difference chrominance component of image or video frame

matrix

Specify the blue-difference chrominance component of the image or video frame as an M-by-N/2 matrix. M and N are the number of rows and columns in the input image.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to YCbCr 4:2:2.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Cr — Red-difference chrominance component of image or video frame

matrix

Specify the red-difference chrominance component of the image or video frame as an M-by-N/2 matrix. M and N are the number of rows and columns in each input image.

Dependencies

To enable this port:

• Set the File name parameter to the name of a multimedia file that contains video or image data. If the specified file contains both audio and video data, set the Write parameter to Video only or Video and audio.

• Set the File color format parameter to YCbCr 4:2:2.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Audio — Audio signal

vector | matrix

Specify the audio signal as an M-element vector or an M-by-N matrix. M is the number of samples in each channel and N is the number of channels.

Dependencies

To enable this port, set the File name parameter to the name of a multimedia file that contains audio data. If the specified file contains both audio and video data, set the Write parameter to Audio only or Video and audio.

Data Types: single | double | int16 | int32 | uint8

Parameters

File name — File name

output.wav (default) | character vector

Specify the name of the multimedia file. The block saves the file in your current folder. To specify a different file or location, click the Save As button.

File type — File type of multimedia file

WAV (default) | AVIMJ2000 | WMA | WMV | MPEG4 | FLAC | MP3 | OGG | OPUS

Specify the type of the multimedia file as one of these options:

• WAV

• AVI

• MJ2000

• WMA

• WMV

• MPEG4

• FLAC

• MP3

• OGG

• OPUS

Write — Type of multimedia

Audio only (default) | Video and audio | Video only

Specify whether the block writes video frames, audio samples, or both to the multimedia file. You can select Video and audio, Video only, or Audio only.

Dependencies

To enable this parameter, set File type to AVI, MPEG4, or OGG.

Audio Quality (0-100) — Quality of audio file

75 (default) | integer in range [0 100]

Specify the quality setting for variable bitrate compression as a scalar in the range [0,100], where 0 is lower quality and higher compression, and 100 is higher quality and lower compression. The default value is 75.

The variable bitrate (VBR) codecs select the appropriate bit rate for each encoded frame depending on the perceptual complexity of the signal and the value you specify in the Audio Quality (0-100) parameter.

Dependencies

To enable this parameter, set File type to OGG, OPUS, or MP3.

Audio Bit Rate (kb/s) — Audio compressor

128 (default) | 64 | 96 | 160 | 192 | 256 | 320

Specify the bit rate of compressed audio files in kilobits per second (kb/s) as 64, 96, 128, 160, 192, 256, or 320. The default value is 128.

On a Windows system, you can set the bit rate to 192, 160,128, or 96.

In general, a larger bit rate value results in higher perceived audio quality.

Dependencies

To enable this parameter, set File type to MPEG4 and Write to Audio only.

Audio compressor — Audio compressor

None (uncompressed) (default) | character vector

Select the type of compression algorithm to use to compress the audio data. This compression reduces the size of the multimedia file. Choose None (uncompressed) to save uncompressed audio data to the multimedia file.

Note

The other items available in this parameter list are the audio compression algorithms installed on your system. For information about a specific audio compressor, see the documentation for that compressor.

Dependencies

To enable this parameter, set Write to Video and audio or Audio only.

Audio data type — Audio data type

16-bit integer (default) | Determine from input data type | 8-bit integer | 24-bit integer | 32-bit integer | 32-bit float | 64-bit float

Select the audio data type. You can use the Audio data type parameter only for uncompressed wave files.

Dependencies

To enable this parameter, set Audio compressor to None (uncompressed).

Video compressor — Video compressor

None (uncompressed) (default) | character vector

Select the type of compression algorithm to use to compress the video data. This compression reduces the size of the multimedia file. Choose None (uncompressed) to save uncompressed video data to the multimedia file.

Note

The other items available in this parameter list are the video compression algorithms installed on your system. For information about a specific video compressor, see the documentation for that compressor.

Dependencies

To enable this parameter, set Write to Video and audio or Video only.

Compression Factor (>1) — Compression factor greater than 1)

10 (default) | integer > 1

Specify the compression factor as an integer greater than 1. The default value of this parameter is 10.

Dependencies

To enable this parameter, set File type to MJ2000 and Video compressor to Lossy.

File color format — File color format

RGB (default) | YCbCr 4:2:2

Select the color format of the data stored in the file. You can select either RGB or YCbCr 4:2:2.

Dependencies

To enable this parameter, set Write to Video and audio or Video only.

Image signal — Image signal

Separate color signals (default) | One multidimensional signal

Specify how the block accepts a color video signal. If you select One multidimensional signal, the block accepts an M-by-N-by-P color video signal, where P is the number of color planes, at one port. If you select Separate color signals, additional ports appear on the block. Each port accepts one M-by-N plane of an RGB video stream.

Dependencies

To enable this parameter, set Write to Video and audio or Video only.

Video Quality (0-100) — Quality of video

75 (default) | integer in range [0 100]

Specify the quality of the video as an integer in the range [0 100]. The default value of this parameter is 75.

Dependencies

To enable this parameter, set File type to MPEG4 and Write to Video only.

Block Characteristics

Data Types	double | integera | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no
a Supports 16- and 32-bit signed and 8-bit unsigned integers.

More About

Cross-Platform Supported File Formats for Audio Files

Audio files can be of the following formats on all platforms:

• WAV

• FLAC

• OGG

• OPUS

• MP3

• MPEG4 (only on Windows 7 and macOS)

The default format is WAV. This block supports MPEG-4 AAC audio files on Windows 7 and macOS. You can use both M4A and MP4 extensions.

The following platform specific restrictions apply when writing these files:

Windows 7

• Only sample rates of 44100 and 48000 Hz are supported.

• Only mono or stereo outputs are allowed for MPEG-4 AAC file format. For all other formats, more than two audio output channels are allowed.

• The output data is padded on both the front and back of the signal, with extra samples of silence.

  Windows AAC encoder places sharp fade-in and fade-out on audio signal, causing signal to be slightly longer in samples when written to disk.

• A minimum of 1025 samples per channel must be written to the MPEG-4 AAC file.

macOS

• Only mono or stereo outputs are allowed for MPEG-4 AAC file format. For all other formats, more than two audio output channels are allowed.

• Not all sampling rates are supported, although the Mac Audio Toolbox™ API do not explicitly specify a restriction.

Linux

• To support OPUS file format on a Linux machine, you must have libsndfile 1.0.29 or a later version installed. On Windows and Mac, this file is shipped with MATLAB and is available under $MATLABROOT/bin/<platform>.

• To write MP3 files on Linux, you must have libsndfile 1.1.0 or a later version installed.

Tips

To run your generated standalone executable application in Shell, set your environment using these commands.

Platform	Command
Mac	setenv DYLD_LIBRARY_PATH "${DYLD_LIBRARY_PATH}:$MATLABROOT/bin/maca64" (csh/tcsh on Apple silicon) export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:$MATLABROOT/bin/maca64 (Bash on Apple silicon) setenv DYLD_LIBRARY_PATH "${DYLD_LIBRARY_PATH}:$MATLABROOT/bin/maci64" (csh/tcsh on Mac Intel®) export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:$MATLABROOT/bin/maci64 (Bash on Mac Intel) For more information, see Append library path to "DYLD_LIBRARY_PATH" in MAC.
Linux	setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:$MATLABROOT/bin/glnxa64 (csh/tcsh) export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$MATLABROOT/bin/glnxa64 (Bash)
Windows	set PATH=%PATH%;%MATLABROOT%\bin\win64

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Usage notes and limitations:

• Host computer only. Excludes Simulink Desktop Real-Time code generation.

• The executable generated from this block relies on prebuilt dynamic library files (.dll files) included with MATLAB. Use the packNGo function to package the code generated from this block and all the relevant files in a compressed zip file. Using this zip file, you can relocate, unpack, and rebuild your project in another development environment where MATLAB is not installed. For more details, see How To Run a Generated Executable Outside MATLAB.

Version History

Introduced before R2006a

R2024a: New Audio Quality (0-100) and Audio Bit Rate (kb/s) parameters

You can now specify audio quality and audio bitrate in the To Multimedia File block for these compressed audio file extensions:

• OGG, OPUS, MP3 –– Audio quality

• MPEG4 –– Audio bit rate

R2023b: Support for writing MP3 files

The To Multimedia File block supports writing MP3 files (.mp3).

R2022b: Support for OPUS audio file format

The To Multimedia File block supports OPUS file format (.opus).