Function: block

BLOCK  Initialize block stream
  Usage: block(source);

  Input parameters:
     source    : Block stream input.
  Output parameters:
     fs        : Sampling rate.
     classid   : Data type.

  BLOCK(source) initializes block data stream from source which
  can be one of the following (the letter-case is ignored for strings):

     'file.wav'
        name of a wav file

     'dialog'
        shows the file dialog to choose a wav file.

     data
        input data as columns of a matrix for each input channel

     'rec'
        input is taken from a microphone/auxilary input;

     {'rec','file.wav'} or {'rec','dialog'} or {'rec',data}
        does the same as 'rec' but plays a chosen audio data simultaneously.

     'playrec'
        loopbacks the input to the output. In this case, the block size
        (in BLOCKREAD) cannot change during the playback.

  BLOCK accepts the following optional key-value pairs

     'fs',fs
        Required sampling rate - Some devices might support only a 
        limited range of samp. frequencies. Use BLOCKDEVICES to list
        supported sampling rates of individual devices. 
        When the target device does not support the chosen sampling rate,
        on-the-fly resampling will be performed in the background.
        This option overrides sampling rate read from a wav file.

        The default value is 44100 Hz, min. 4000 Hz, max. 96000 Hz

     'L',L
        Block length - Specifying L fixes the buffer length, which cannot be
        changed in the loop.

        The default is 1024. In the online mode the minimum is 32.

     'devid',dev
        Whenever more input/output devices are present in your system,
        'devid' can be used to specify one. For the 'playrec' option the
        devId should be a two element vector [playDevid, recDevid]. List
        of the installed devices and their IDs can be obtained by
        BLOCKDEVICES.

     'playch',playch
        If device supports more output channels, 'playch' can be used to
        specify which ones should be used. E.g. for two channel device, [1,2]
        can be used to specify channels.

     'recch',recch
        If device supports more input channels, 'recch' can be used to
        specify which ones should be used.

     'outfile','file.wav'
        Creates a wav file header for on-the-fly storing of block data using
        BLOCKWRITE. Existing file will be overwritten. Only 16bit fixed
        point precision is supported in the files.

     'nbuf',nbuf
        Max number of buffers to be preloaded. Helps avoiding glitches but
        increases delay.

     'loadind',loadind
        How to show the load indicator. loadind can  be the following:

           'nobar'
              Suppresses any load display.

           'bar'
              Displays ascii load bar in command line (Does not work in Octave).

           obj
              Java object which has a public method updateBar(double).

  Optional flag groups (first is default)

     'noloop', 'loop'
        Plays the input in a loop.

     'single', 'double'
        Data type to be used. In the offline mode (see below) the flag is
        ignored and everything is cast do double.

     'online', 'offline'
        Use offline flag for offline blockwise processing of data input or a
        wav file without initializing and using the playrec MEX.

Url: http://ltfat.github.io/doc/blockproc/block.html

See also: blockread, blockplay, blockana, blocksyn, demo_blockproc_basicloop, demo_blockproc_slidingsgram.

Package: ltfat