BPI-R1 MIC
thank chaos.dennis do this test:
i write about this, because i found very few sources and had to tumble a lot around to get it working. This is a quick walk through to give you a hint where to start. I asume for simplicity that you stay always in /root directory as root user. If something fails, look if the files are written and paths are right. It is adressed for more advanced users who know what they are basically doing.
This is done with bananian 15.08 on Kernel 3.4. Other kernels < 4.4 do not work. It is a headless server with no HDMI pluged in.
A. Basic Setup
Install alsa (renove pulseaudio if present):
# apt-get install alsa-base alsa-utilsConfigure asound.conf
# nano /etc/asound.confShould look like:
pcm.!default { type hw card 0 # for headphone, turn 1 to 0 device 0 } ctl.!default { type hw card 0 # for headphone, turn 1 to 0 }Shutdown, make a cold boot
Call the alsamixer
# alsamixerPress F5. Your channels should be setup like the attached file at the bottom of this post, or compare it to amixer output:
# amixer Simple mixer control 'Master',0 Capabilities: pvolume pvolume-joined Playback channels: Mono Limits: Playback 0 - 63 Mono: Playback 45 [71%] Simple mixer control 'Master Capture Mute',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [off] Simple mixer control 'LineL',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'LineR',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Linein Pre-AMP',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 7 [100%] Simple mixer control 'Mic Input Mux',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 15 Mono: 15 [100%] Simple mixer control 'Mic Power',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Mic1 Boost',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Mic1 gain',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 3 Mono: 3 [100%] Simple mixer control 'Mic2 Boost',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Mic2 gain',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 0 [0%] Simple mixer control 'MicL',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 3 Mono: 1 [33%] Simple mixer control 'MicR',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 3 Mono: 3 [100%] Simple mixer control 'Playback',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Capture',0 Capabilities: cvolume cvolume-joined Capture channels: Mono Limits: Capture 0 - 7 Mono: Capture 7 [100%] Simple mixer control 'ADC Input Mux',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 7 [100%] Simple mixer control 'Fm output',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 7 [100%] Simple mixer control 'FmL',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'FmR',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'LINEIN APM',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 7 [100%] Simple mixer control 'Ldac Left Mixer',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Ldac Right Mixer',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Left Capture Mute',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'MIC output volume',0 Capabilities: volume volume-joined Playback channels: Mono Capture channels: Mono Limits: 0 - 7 Mono: 7 [100%] Simple mixer control 'Rdac Right Mixer',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'Right Capture Mute',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on]This step is critical. One false muted channel and you are out of the game.
Test recording.
# arecord -LShould show a device.
# arecord -f S16_LE -r 44100 -t wav test.wavShould make kind of Sound. Stop it with ctr-c and check the file.
B. SoX Recording / Streaming
Install SoX
# apt-get install sox libsox-fmt-allSox gives you tools like: sox, rec and play. I would suggest you install it on the client pc too.Record striaght to mp3
# rec -c 2 -C 64 test.mp3-c 2 two channels
-C 64 tell the encoder to produce a 64kbit/s mp3
Stop it with ctr-c, check the output.
Listen to it live over LAN
Banana:
# rec -c 2 -C 64 -t mp3 - | netcat -l -p 9000-t mp3 - produce mp3 stream to stdout
Client:
# netcat <banana ip> 9000 | vlcWorks? Great! Live listening is important to play around and test the mic.
Listen and record at same time
# rec -c 2 -C 64 -t mp3 - | tee test.mp3 | netcat -l -p 9000Poor man's streaming server
# apt-get install openbsd-inetd tcpdEdit config file:
# nano /etc/inetd.confInsert this at the end:
9000 stream tcp nowait nobody /usr/bin/tail tail -f /test.mp3Restart service
# service openbsd-inetd restartStart recording on banana:
# rec -c 2 -C 64 /test.mp3Connect via client:
# netcat <banana ip> 9000 | vlc -
C. Advanced Recording
Devide recording and postprocessing in two parts
# rec -t raw - remix - | sox -t raw -r 48000 -c 1 -b 16 -e signed-integer - -t mp3 -c 1 -C 32 test.mp3
Recording:
-t raw - forward raw input to pipe
remix - Mix the two channels to one
Encoding:
-t raw -r 48000 -c 1 -b 16 -e signed-integer - tell sox what kind of strean comes from stdin
-t mp3 -c 1 -C 32 test.mp3 and what goes out
Note that it is switched to mono from here with -c 1 and the mp3 bitrate is cut in half. Live listening to the strean does not work anymore, i asume it is because of the non regulare output from pipeing and processing in a second step.
Reduce noise
The mic input is pretty bad, lot of white noise. Sox can deal with it.
Make a sample "silent" file:
# rec -t raw test.raw remix - trim 0 10trim 0 10 record 10 seconds
Test it at client pc:
# play -r 48000 -c 1 -b 16 -e signed-integer test.rawCreate profile file:
# sox -r 48000 -c 1 -b 16 -e signed-integer test.raw -n trim 0 2 noiseprof raw-profileRecord with noise canceld
# rec -t raw - remix - noisered raw-profile 0.2 | sox -t raw -r 48000 -c 1 -b 16 -e signed-integer - -t mp3 -c 1 -C 32 test.mp3Play with the factor of 0.2 to regulate the intensity of cancellation.
D. Record 24/7
My goal of this....
Create a script:
# nano /root/record.shInsert the following:
#!/bin/bash
# send sigterm and wait for exit of the process
function stop() { kill $@; while kill -0 $@; do sleep 1; done; }
function log() { echo $(date +%T) $@; }
log "Stopping previus recording"
stop `pidof rec` &> /dev/null
DATE=`date "+%Y.%m.%d"`
log "Recording $DATE.mp3"
rec -q -t raw - remix - noisered /root/raw-profile 0.2 | \
sox -v 2.0 -t raw -r 48000 -c 1 -b 16 -e signed-integer - \
-t mp3 -r 22050 -c 1 -C -9.2 /root/$DATE.mp3
log "Done $DATE.mp3"Recording:
-q less output
Encoding: -v 2.0 Make the input stream louder
-r 22050 encode to a lower sample rate
-C -9.2 Create a low quality VBR mp3
Fileszie ~100mb per day. If you want smaller files, a 8000 sanple rate gives you a gsm grade quality.
A very good article to sample rate: http://wiki.audacityteam.org/wiki/Sample_Rates
Make it executable
# chmod +x record.shEdit crontab:
# env EDITOR=nano crontab -eInsert at the end the following:
PATH=/usr/local/bin:/usr/local/sbin:/sbin:/usr/sbin:/bin:/usr/bin
0 0 * * * /root/record.sh >> /root/re cord-mic.logA new recording should start every day at midnight.
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