Audio system

This page is intended as a collection of all things audio.

Audio Features

The Pandora has a high quality Digital to Analogue Converter (DAC). The sound signal from the processor is passed to an analogue amplifier, and at this point a signal from the volume control wheel is applied (so the OS has no visibility of the volume wheel, you have a final physical control over the volume). There is a built in microphone (on the right hinge), and a multi-terminal 3.5mm jack. Plugging in to the jack will disconnect the internal speakers. Note that ipod specific headphones use a different pin-out and are not compatible with the Pandora. Normal stereo headphones are compatible.

This jack input allows to plug a headphone + microphone headset (4 pins 3.5mm jack). See http://www.openpandora.org/downloads/PANDORA_Hackers_manual_v100.pdf page 18.

Boosting the volume

From urjaman[1]: If you want to over-amplify (will crackle if you overdo it == play loud recording with high volume) the audio with the software volume control (eg. I just watched firefly with my Pandora and really couldn't hear it properly with the integrated speakers because it was too quiet recording), modify .asoundrc(add the + line, without the +):

pcm.softvol {
        type softvol
        slave {
                pcm     "dmixed"
        }
        control {
                name    "Master"
                card 0
        }
+       max_dB 12.0
}

You can change the max_dB to suit yourself, but 12 is a good starting value if you have no idea (it's what the winamp preamp allows by default, some audio card drivers, etc). If it's too loud (crackling) after this, you can also just compensate with the XFCE mixer (or alsamixer from terminal) (the analog volume scroll wont fix this).

Recording

How to enable audio recording by MWeston:

• In the mixer control utility, select SELECT CONTROLS and enable 'Left Input Source' and 'Right Input Source'
• under the OPTIONS tab, set Left Input Source to MAIN MIC (for internal mic) or LINE IN when A/V cables are available
• Set Right Input Source to SUB MIC for use with four conductor headset or to LINE IN when A/V cables are available
• Under CAPTURE tab, increase the level to whatever is necessary (start at midpoint)
• Under the PLAYBACK tab, increase the INPUT BOOST to whatever is necessary (start low!)
• open a terminal window and type:

arecord -f cd -D hw:0,1 | aplay

This will play the input through the speakers. It has a good half second delay but you can still get into some interesting feedback loops if you're not careful.

• to record the input devices to a file, move to an SD card directory (strongly don't recommend writing to NAND as you know) and type:

arecord -t wav -f cd -D hw:0,1 test.wav

(call the file whatever you want and you could also type the full path to SD card here too)

• then listen to it with:

aplay test.wav