### Build and Install SpeexDSP

Source: https://github.com/voice-engine/ec/wiki/Home

This snippet details the steps to build and install the SpeexDSP library. It includes installing prerequisite packages like autoconf, libtool, and fftw3-dev, cloning the official repository, running the autogen script, configuring the build with FFTW3 and NEON support, compiling the code, and finally installing it system-wide.

```bash
sudo apt-get install -y autoconf libtool libfftw3-dev
git clone https://github.com/xiph/speexdsp.git
cd speexdsp
./autogen.sh
./configure --with-fft=gpl-fftw3 --enable-neon
make
sudo make install
```

--------------------------------

### Run ec with PulseAudio

Source: https://github.com/voice-engine/ec/blob/master/README.md

Example command to execute the 'ec' tool, specifying PulseAudio hardware devices for input and output. This assumes PulseAudio has been configured as shown previously.

```shell
./ec -i plughw:0 -o plughw:0
```

--------------------------------

### PulseAudio Setup for ec

Source: https://github.com/voice-engine/ec/blob/master/README.md

Commands to configure PulseAudio by loading specific modules for sink and source, and setting them as the default audio devices. This prepares PulseAudio to work with the 'ec' tool.

```APIDOC
pacmd load-module module-pipe-sink sink_name=ec.sink format=s16 rate=16000 channels=1 file=/tmp/ec.input
pacmd load-module module-pipe-source source_name=ec.source format=s16 rate=16000 channels=2 file=/tmp/ec.output
pacmd set-default-sink ec.sink
pacmd set-default-source ec.source
```

--------------------------------

### Install and Configure ALSA FIFO Plugin

Source: https://github.com/voice-engine/ec/blob/master/README.md

Provides instructions to clone, build, and install a custom ALSA FIFO plugin. This plugin enables the use of named pipes as ALSA capture devices, facilitating integration with applications like ec.

```shell
git clone https://github.com/voice-engine/alsa_plugin_fifo.git
cd alsa_plugin_fifo
make && sudo make install

# Copy configuration to apply the plugin
cp asound.conf ~/.asoundrc
```

--------------------------------

### ec_hw Usage Example

Source: https://github.com/voice-engine/ec/blob/master/README.md

Demonstrates how to use 'ec_hw' by specifying input device, channel count, loopback channel, and microphone channel list. It also shows how to capture processed audio to a file.

```shell
# terminal #1, run ec_hw
./ec_hw -i plughw:1 -c 8 -l 7 -m 0,1,2,3

# terminal #3, record
cat /tmp/ec.output > 16k_s16le_4_channels.raw
```

--------------------------------

### Build Voice Engine EC Project

Source: https://github.com/voice-engine/ec/blob/master/README.md

Installs necessary development libraries for ALSA and SpeexDSP, clones the project repository, and compiles the ec and ec_hw executables using the make build system.

```shell
sudo apt-get -y install libasound2-dev libspeexdsp-dev
git clone https://github.com/voice-engine/ec.git
cd ec
make
```

--------------------------------

### Run ec for AEC with ALSA Devices

Source: https://github.com/voice-engine/ec/blob/master/README.md

Demonstrates how to execute the ec application for acoustic echo cancellation. It shows how to display help options and specifies input/output ALSA devices and channels for processing.

```shell
# terminal #1, run ec
./ec -h
./ec -i plughw:1 -o plughw:1 -s
```

--------------------------------

### ec_hw Command Line Options

Source: https://github.com/voice-engine/ec/blob/master/README.md

Shows the available command-line arguments for the 'ec_hw' tool, which is designed for devices with hardware audio loopback capabilities.

```shell
./ec_hw -h
```

--------------------------------

### Data Flow for ec with Named Pipes

Source: https://github.com/voice-engine/ec/blob/master/README.md

Illustrates the data flow for the ec application when hardware loopback is not available. It shows how ec reads playback audio from a named pipe (`/tmp/ec.input`) and writes processed audio to another named pipe (`/tmp/ec.output`).

```shell
# terminal #2, play 16k fs, 16 bits, 1 channel raw audio
cat 16k_s16le_mono_audio.raw > /tmp/ec.input

# terminal #3, record
cat /tmp/ec.output > 16k_s16le_stereo_audio.raw
```

--------------------------------

### ec for Raspberry Pi with ReSpeaker 2 Mic Hat

Source: https://github.com/voice-engine/ec/blob/master/README.md

Command to run 'ec' on a Raspberry Pi with a ReSpeaker 2 Mic Hat, accounting for a 200ms delay between playback and recording. It specifies input and output devices.

```shell
./ec -i plughw:1 -o plughw:1 -d 200
```

--------------------------------

### ec_hw Input Device Selection

Source: https://github.com/voice-engine/ec/blob/master/README.md

Command to list available audio input devices on the system, which is necessary for correctly specifying the input device name when using 'ec_hw'.

```shell
arecord -L
```

--------------------------------

### Disable PulseAudio Autospawn

Source: https://github.com/voice-engine/ec/blob/master/README.md

Instructions to disable PulseAudio's automatic spawning feature by modifying client configuration files. This is necessary if PulseAudio needs to be manually managed or disabled.

```APIDOC
autospawn=no
# Add this line to ~/.config/pulse/client.conf or /etc/pulse/client.conf
# Then run: pulseaudio -k
```

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