na_play1

Usage

Overview

na_play plays digital audio data to the system's audio input device from the specified file(s). It supports a variety of file formats and native audio devices.

The following option flags are recognized:

-h

Prints a short summary of usage to standard output.

-itype type

Input file type. Usually, the input type can be determined from the file's headers, so this option is not required except for raw (unheadered) data. Supported types are currently: nist, est, esps, snd, riff, aiff, audlab, raw, ascii.

-n channels

Number of channels, in an unheadered input file. Again, this can usually be determined from the headers. Default is 1.

-f sampling rate

Sampling rate, for an unheadered input file. Default is 16000.

-ibo byte order

Byte order, for an unheadered input file. Default is system byte order. Recognized values are: MSB, LSB, native, nonnative.

-iswap

Swap bytes in an unheadered input file.

-istype type

Sample type for an unheadered input file. Recognized values are: short, mulaw, byte, ascii.

-c channel

Select a single channel (starting at 0) for playback. This option plays only the specified channel and discards all others.

-start time

Select a subsection of the file, starting at this time (specified in seconds).

-end time

Select a subsection of the file, ending at this time (specified in seconds).

-from sample

Select a subsection of the file, starting at this offset (specified in number of samples).

-to sample

Select a subsection of the file, ending at this offset (specified in number of samples).

-p protocol

Use the specified audio device protocol. The list of supported types varies between platforms, and can be obtained using the -h flag.

-command command

If the "audio_command" protocol is specified, this argument must be given to select the command used to play the waveform. A temporary file is created and passed in the environment variable FILE. The sample rate is passed in the environment varialbe SR.

-basic

Treat unheadered input files as 8kHz mu-law data (i.e. audio/basic MIME type)

-quality high | low

Select the quality of output. "high" will ensure that proper resampling is used. "low" means to play as fast as possible with a minimum of processor time.

-server host

Specifies the host to play sound on, when using a network-aware audio protocol (such as NAS)

-scale scale

Change the gain (volume) of the signal. The argument is a number relative to 1.0, which is the default.

-v

Be verbose (i.e. print file names when playing)

-wait

Pause for a keystroke between each file.

Environment

NA_PLAY_PROTOCOL

Audio protocol to use (as in the -p flag)

NA_PLAY_COMMAND

Command used to play audio when using the audio_command protocol.

NA_PLAY_HOST

Host to play audio on when using a network audio protocol.

NA_PLAY_QUALITY

Playback quality (low or high)

Examples

To play the section of foo.wav from 1.5 to 3.2 seconds:

$ na_play -start 1.5 -end 3.2 foo.wav

To play samples 3600 to 42000 of channel 1 of bar.wav:

$ na_play -from 3600 -to 4200 -c 1 foo.wav