Speex

Taken from http://www.speex.org/ : Speex is an Open Source/Free Software patent-free audio compression format designed for speech. The Speex Project aims to lower the barrier of entry for voice applications by providing a free alternative to expensive proprietary speech codecs.

Installation

• Select the package in Buildroot menuconfig:

$ make menuconfig

Package Selection for the target  --->
    Audio libraries and applications  --->
        [*]   speex

• Compile

$ make

• Reflash your rootfs

Usage

Speex can be used from shell, thanks to the speexenc and speexdec command line tools:

• If ALSA Audio In was setup correctly, record a sound

# arecord /tmp/toto.wav
Recording WAVE '/tmp/toto.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono

• Then compress it:

# speexenc /tmp/toto.wav /tmp/toto.spx
Encoding 8000 Hz audio using narrowband mode (mono)

# ls -al /tmp/toto.*
-rw-r--r--    1 root     root        13303 Jan  1 01:24 /tmp/toto.spx
-rw-r--r--    1 root     root        53292 Jan  1 01:23 /tmp/toto.wav

• To decompress it to a file:

# speexdec /tmp/toto.spx /tmp/toto_dec.wav
Decoding 8000 Hz audio using narrowband mode (mono)
Encoded with Speex 1.2rc1

• To decompress it and play it "on the fly" (needs OSS emulation):

# modprobe snd-pcm-oss
# modprobe snd-mixer-oss

# speexdec /tmp/toto.spx

Programming with Speex

http://www.speex.org/docs/manual/speex-manual/node7.html

Links

• http://www.speex.org/docs/manual/speex-manual/