parec/pacat produces unusable files

[hackeron]

# pacat -r --channels=1 --format=s16le --rate=22050 -d alsa_input.usb_device_471_329_01690000D6490703_if1_alsa_capture_0 >testfile # file testfile testfile: data

# arecord f S16_LE -r 22050 -D hwplug:1 testfile # file testfile testfile: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 22050 Hz

The parec/pacat files are also not usable by mencoder, sox, ffmpeg, vlc and other players I've tried.

I'm willing to accept I'm doing something wrong, but the files created by pacat seem to be unusable.

I'm using pulse audio on Ubuntu and these are the packages I have installed: ii libao-pulse 0.9.3-1 ii libpulse-browse0 0.9.6-1ubuntu2 ii libpulse-mainloop-glib0 0.9.6-1ubuntu2 ii libpulse0 0.9.6-1ubuntu2 ii padevchooser 0.9.3-2 ii paman 0.9.3-1build2 ii paprefs 0.9.5-1 ii pavucontrol 0.9.4-1build2 ii pavumeter 0.9.2-1 ii pulseaudio 0.9.6-1ubuntu2 ii pulseaudio-esound-compat 0.9.6-1ubuntu2 ii pulseaudio-module-gconf 0.9.6-1ubuntu2 ii pulseaudio-module-hal 0.9.6-1ubuntu2 ii pulseaudio-module-x11 0.9.6-1ubuntu2 ii pulseaudio-module-zeroconf 0.9.6-1ubuntu2 ii pulseaudio-utils 0.9.6-1ubuntu2

I'm using the default default.pa.

[hackeron]

Sorry about the formatting, here it is with wiki syntax:

# pacat -r --channels=1 --format=s16le --rate=22050 -d alsa_input.usb_device_471_329_01690000D6490703_if1_alsa_capture_0 >testfile
# file testfile
testfile: data

# arecord f S16_LE -r 22050 -D hwplug:1 testfile
# file testfile
testfile: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 22050 Hz

[jbglaw]

These tools operate on raw PCM audio, not on sound files. That is, in parec's output, there's no WAF/RIFF header, so `file' won't recognize it as audio.

You'll need to add the needed header, which can eg. be done with `sox'.

[lennart]

As jbglaw correctly mentioned pacat/parec only handle raw PCM streams. If you want to play audio files like .wav use "paplay".

[hackeron]

Oh, right ok. Yes, this worked:

pacat -r --channels=1 --format=s16le --rate=22050 -d alsa_input.usb_device_471_329_01690000D6490703_if1_alsa_capture_0 | sox -t sw -r 22050 -c 1 - -t wav - > testfile.wav

[jbglaw]

I wonder why you don't use -t raw for input?

[hackeron]

Well, I've been experimenting and so far all my attempts just generate noise :(

My latest attempt is
pacat -r --channels=1 --format=s16ne --rate=44100 -d alsa_input.%s | sox -sw -t raw -r 44100 -c 1 - -t wav

but I'm just getting pure noise :( -- Any ideas?

[hackeron]

Well, actually not pure noise, but something so heavily distorted you can't make out a single word.

Can someone give an example of a parec+sox combination that works for them?

[lennart]

hackeron: is this 0.9.6 or 0.9.7-svn?

Unfortunately sox seems to be totally broken right now, I cannot teach it anymore to read raw data from stdin. However, this works fine:

$ parec > foo.wav ^{C $ pacat foo.wav}

This will record some audio data, and play it back again.