Raspberry Pi Realtime Audio Processing

RtAudio

완전히 C++기반으로 구현된 오디오 라이브러리.

설치방법 on Raspberry Pi

sudo apt-get install autoconf libtool automake

sudo apt install libasound2 libasound2-dev

git clone https://github.com/thestk/rtaudio.git

./autogen.sh

make

설치확인

(* 라즈베리파이의 jack에 스피커를 연결하고, USB mic를 연결한다.)

cd rtaudio/tests

./audioprobe     --> input device id와 output device id확인

./testall

./duplex 1 44100 [input device id] [output device id]

Extreme Latency Improving

불필요한 service제거, 오버클럭, headless RPi, On-board audio, USB audio interface

https://wiki.linuxaudio.org/wiki/raspberrypi

---

PortAudio

설치방법 on Raspberry Pi

라즈베리파이에 설치하기 위해서는 반드시 직접 빌드를 해야한다. 그리고 OSS보다는 ALSA를 backend API로 쓰는게 좋다고한다.

(The OSS sound API is very old and not well supported. It is recommended that you use the ALSA sound API)

소스부터 직접 빌드하기

sudo apt-get install libasound2-dev

wget http://www.portaudio.com/archives/pa_stable_v190600_20161030.tgz

tar -xvzf pa_stable_v190600_20161030.tgz

cd portaudio

./configure --with-alsa

make

sudo make install

sudo ldconfig

(정상 설치 확인: device list보기)

cd bin

./pa_devs

기존에 설치된 portaudio 삭제하기

sudo apt autoremove libportaudio2

(만약 소스부터 직접 빌드했다면)

cd portaudio

sudo make clean

sudo make uninstall

sudo make -n uninstall

sudo make -B uninstall

라즈베리파이 오디오 세팅하기

https://www.raspberrypi.org/documentation/configuration/audio-config.md

ALSA 정상 동작 확인하기: 원본

sudo apt-get install alsa-utils

sudo apt-get install lame

sudo apt-get install mpg321

sudo modprobe snd-bcm2835

(To check if the driver is loaded you can type:)

sudo lsmod | grep 2835

(Select the output device for sound (0=auto, 1=analog, 2=HDMI):)

sudo amixer cset numid=2

* Test the installation:

aplay /usr/share/sounds/alsa/Front_Center.wav

speaker-test -t sine -f 440 -c 2 -s 1

mpg321 “Mannish Boy.mp3”

* It you get the following error message:

-> ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.front

Edit the file /usr/share/alsa/alsa.conf:

sudo vim /usr/share/alsa/alsa.conf

change the line “pcm.front cards.pcm.front” to “pcm.front cards.pcm.default”

* If you are using HDMI and cannot hear any audio at all change the following PI configuration setting:

edit the RasPI configuration file:

sudo vim /boot/config.txt

uncomment the line:

hdmi_drive=2

save the file and reboot the PI

Resources:

http://jeffskinnerbox.wordpress.com/2012/11/15/getting-audio-out-working-on-the-raspberry-pi/

http://elinux.org/R-Pi_Troubleshooting

---

JACK

https://wiki.linuxaudio.org/wiki/raspberrypi

https://jackaudio.org/

---

PyAudio

git clone https://people.csail.mit.edu/hubert/git/pyaudio.git

http://people.csail.mit.edu/hubert/pyaudio/

* rpi에 pyaudio구현 사례: https://github.com/CharlieHouse/RPi_SISO_ANC/blob/master/python_tonal_anc.py