na_record1

Usage

Overview

na_record records digital audio data from the system's audio input device and writes it to the specified file. It supports a variety of output file formats and native audio devices.

The following option flags are recognized:

-h

Prints a short summary of usage to standard output.

-f sampling rate

Sets the input sampling rate (in samples per second, i.e. Hz). Not all devices support all sampling rates, so it may be desirable to set this separately from the output sampling rate.

-audiodevice device

Sets the audio device to record from, if supported by the audio protocol chosen (e.g. /dev/dsp, /dev/audio)

-time seconds

Stops recording after the specified number of seconds.

-o file

Writes sound output to the specified file

-otype type

Specifies the file format to use for output. Supported types currently include nist, est, dsps, snd, riff, aiff, audlab, raw, and ascii. The -h flag will show the most accurate list. The default type is nist.

-F sampling rate

Sets the output sampling rate (again, in samples per second, i.e. Hz). If this differs from the input sampling rate, resampling will be done. Defaults to 16000Hz.

-obo byte order

Sets the output byte order. Supported values are MSB, LSB, and native. Many file formats have their own byte order, or are byte order independent, so this isn't tremendously useful except for raw data. The default is the native byte order for the system audio device.

-oswap

Swap bytes when saving to output.

-ostype sample type

Sets the sample type of the output. Supported values are short, mulaw, byte, or ascii. Again, this is usually implied by the file format, so should only be used for raw data. The default is short (i.e. 16-bit PCM).

-p audio device protocol

Selects an audio device protocol (i.e. type of audio device) to use. This varies between different installations of Speech Tools, but defaults to the most 'native' audio device, usually Open Sound System on Linux and *BSD and /dev/audio on Solaris.

Environment

NA_PLAY_PROTOCOL

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

NA_PLAY_HOST

Host to record audio from when using a network audio protocol.

Examples

To record five seconds of audio from /dev/dsp1 (on Linux) to foo.wav in RIFF format at 32kHz:

$ na_record -time 5 -audiodevice /dev/dsp1 -o foo.wav -otype RIFF -f 32000

To record one second of audio to bar.wav in raw format in 8kHz mu-law:

$ na_record -time 1 -o bar.wav -otype raw -ostype mulaw -f 8000