To Multimedia File
Stream video frames and audio samples to multimedia file
Library
Sinks
dspsnks4
Description
The To Multimedia File block writes video frames, audio samples, or both to
a multimedia (.avi, .wav, .wma, .mp4, .ogg, .flac, or .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), may 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.
Cross-Platform Supported File Formats for Audio Files
Audio files can be of the following formats on all platforms:
WAV
FLAC
OGG
OPUS
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>
.
Ports
Port | Description | |||
---|---|---|---|---|
Image | M-by-N-by-3 matrix RGB, Intensity, or YCbCr 4:2:2 signal. | |||
R, G, B | Matrix that represents one plane of the RGB video stream. Inputs to the R, G, or B port must have the same dimensions and data type. | |||
Audio | M-by-N matrix. M is the number of samples in each channel, and N is the number of channels. | |||
Y, Cb, Cr | Matrix that represents one frame of the YCbCr video stream. The Y, Cb, and Cr ports use the following dimensions:
|
Dialog Box
The Main pane of the To Multimedia File block dialog appears as follows.
- File name
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
Specify the file type of the multimedia file. You can select
AVI
,WAV
,MJ2000
,WMA
,WMV
,MPEG4
,FLAC
,OGG
, orOPUS
. By default, the File type is set toWAV
.- Write
Specify whether the block writes video frames, audio samples, or both to the multimedia file. You can select
Video and audio
,Video only
, orAudio only
. This parameter is visible only when you set File type toAVI
,MPEG4
,OGG
orOPUS
.- Audio compressor
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.
- Audio data type
Select the audio data type. You can use the Audio data type parameter only for uncompressed wave files.
- Video compressor
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.
- Compression Factor (>1)
Specify the compression factor as an integer scalar greater than
1
. This parameter is applicable only when the File type is set toMJ2000
and Video compressor is set toLossy
. By default, this parameter is set to10
.- File color format
Select the color format of the data stored in the file. You can select either
RGB
orYCbCr 4:2:2
.- Image 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 selectSeparate color signals
, additional ports appear on the block. Each port accepts one M-by-N plane of an RGB video stream.- Video Quality (0-100)
Quality of the video specified as an integer scalar in the range [
0 100
]. This parameter is applicable only when File name is set toMPEG4
and Write is set toVideo only
. By default, this parameter is set to75
.
Troubleshooting
Running an Executable Outside MATLAB
To run your generated standalone executable application in Shell, you need to set your environment to the following:
Platform | Command |
---|---|
Mac |
For more information, see Append library path to "DYLD_LIBRARY_PATH" in MAC. |
Linux |
|
Windows |
|
Supported Data Types
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.
Port | Supported Data Types | Supports Complex Values? |
---|---|---|
Image |
| No |
R, G, B | Same as Image port | No |
Audio |
| No |
Y, Cb, Cr | Same as Image port | No |