Read NeXT/SUN (.au) sound file
Graphical Interface
As an alternative to auread, use the Import Wizard. To activate the Import Wizard, select Import data from the File menu.
Syntax
y = auread('aufile')
[y,Fs,bits] = auread('aufile')
[...] = auread('aufile',N)
[...] = auread('aufile',[N1,N2])
siz = auread('aufile','size')
Description
y = auread('aufile') loads a sound file specified by the string aufile, returning the sampled data in y. The .au extension is appended if no extension is given. Amplitude values are in the range [-1,+1]. auread supports multi-channel data in the following formats:
[y,Fs,bits] = auread('aufile') returns the sample rate (Fs) in Hertz and the number of bits per sample (bits) used to encode the data in the file.
[...] = auread('aufile',N) returns only the first N samples from each channel in the file.
[...] = auread('aufile',[N1 N2]) returns only samples N1 through N2 from each channel in the file.
siz = auread('aufile','size') returns the size of the audio data contained in the file in place of the actual audio data, returning the vector siz = [samples channels].
Write NeXT/SUN (.au) sound file
Syntax
Description
auwrite(y,'aufile') writes a sound file specified by the string aufile. The data should be arranged with one channel per column. Amplitude values outside the range [-1,+1] are clipped prior to writing. auwrite supports multi-channel data for 8-bit mu-law, and 8- and 16-bit linear formats.
auwrite(y,Fs,'aufile') specifies the sample rate of the data in Hertz.
auwrite(y,Fs,N,'aufile') selects the number of bits in the encoder. Allowable settings are N = 8 and N = 16.
auwrite(y,Fs,N,'method','aufile') allows selection of the encoding method, which can be either mu or linear. Note that mu-law files must be 8-bit. By default, method = 'mu'.
Create a new Audio Video Interleaved (AVI) file
Syntax
Description
aviobj = avifile(filename) creates an AVI file, giving it the name specified in filename, using default values for all AVI file object properties. If filename does not include an extension, avifile appends .avi to the filename. AVI is a file format for storing audio and video data.
avifile returns a handle to an AVI file object, aviobj. You use this object to refer to the AVI file in other functions. An AVI file object supports properties and methods that control aspects of the AVI file created.
aviobj = avifile(filename,'Param',Value,'Param',Value,...) creates an AVI file with the specified parameter settings. This table lists available parameters.
| Parameter | Value | Default | |
'colormap' | An m-by-3 matrix defining the colormap to be used for indexed AVI movies, where m must be no greater than 256 (236 if using Indeo compression). You must set this parameter before calling addframe, unless you are using addframe with the MATLAB movie syntax. | There is no default colormap. | |
'compression' | A text string specifying which compression codec to use. | ||
| On Windows:'Indeo3'''Cinepak''MSVC''None' | On Unix: 'None' | 'Indeo3', on Windows. 'None' on Unix. |
| To use a custom compression codec, specify the four-character code that identifies the codec (typically included in the codec documentation). The addframe function reports an error if it can not find the specified custom compressor. | ||
'fps' | A scalar value specifying the speed of the AVI movie in frames per second (fps). | 15 fps | |
'keyframe' | For compressors that support temporal compression, this is the number of key frames per second. | 2 key frames per second. | |
'name' | A descriptive name for the video stream. This parameter must be no greater than 64 characters long. | The default is the filename. | |
'quality' | A number between 0 and 100. This parameter has no effect on uncompressed movies. Higher quality numbers result in higher video quality and larger file sizes. Lower quality numbers result in lower video quality and smaller file sizes. | 75 | |
You can also use structure syntax to set AVI file object properties. For example, to set the quality property to 100 use the following syntax:
Example
This example shows how to use the avifile function to create the AVI file example.avi.
fig=figure;
set(fig,'DoubleBuffer','on');
set(gca,'xlim',[-80 80],'ylim',[-80 80],...
'NextPlot','replace','Visible','off')
mov = avifile('example.avi')
x = -pi:.1:pi;
radius = 0:length(x);
for k=1:length(x)
h = patch(sin(x)*radius(k),cos(x)*radius(k),...
[abs(cos(x(k))) 0 0]);
set(h,'EraseMode','xor');
F = getframe(gca);
mov = addframe(mov,F);
end
mov = close(mov);
aviinfo
Return information about an Audio Video Interleaved (AVI) file
Syntax
Description
fileinfo = aviinfo(filename) returns a structure whose fields contain information about the AVI file specified in the string, filename. If filename does not include an extension, then .avi is used. The file must be in the current working directory or in a directory on the MATLAB path.
fileinfo structure are shown below.aviread
Read an Audio Video Interleaved (AVI) file.
Syntax
Description
mov = aviread(filename) reads the AVI movie filename into the MATLAB movie structure mov. If filename does not include an extension, then .avi is used. Use the movie function to view the movie, mov. On UNIX, filename must be an uncompressed AVI file.
mov has two fields, cdata and colormap. The content of these fields varies depending on the type of image.
| Image Type | mov.cdata Field | mov.colormap Field |
Truecolor | ||
Indexed |
mov = aviread(filename,index) reads only the frame(s) specified by index. index can be a single index or an array of indices into the video stream. In AVI files, the first frame has the index value 1, the second frame has the index value 2, and so on.
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