Add pedalboard.io.AudioStream support for Linux (#368)

* pedalboard.io: Add Linux support for AudioStream class

Problem

AudioStream is currently not supported on Linux due to macro definitions
in the build script that disable AudioStream functionalities

Solution

Add the JUCE_MODULE_AVAILABLE_juce_audio_devices macro to ALL_CPPFLAGS,
add link flag with the alsa-lib JUCE dependency for interacting with sound
devices in Linux, fix audioDeviceIOCallback to support the live audio playback
feature

Result

AudioStream is now supported on Linux as well as Windows and MacOS

* Fix reverb example to use len instead of .frames for SoundFile class

* Add example for audio monitoring with Pedalboard effects

* Fix formatting

* Add alsa-lib package in wheel builder for static linking

* Add libasound2-dev dependency for the pre-build on ubuntu-20.04

* Add libasound2-dev dependency to Linux actions

* Comment out "delete existing cache" step.

* Include Linux in AudioStream tests, remove create_stream_fails_on_linux test

* Update test_audio_stream.py

* Update test_audio_stream.py

* Update test_audio_stream.py

* Add step to remove libasound before running tests.

* Update all.yml

* Add empty string handling in AudioStream constructor

* Add snd-dummy kernel module for testing AudioStream on linux

* Remove uninstallation of libasound

* Handle None audio devices.

* Is the default device name empty?

* Return None for an audio device name if the device name is the empty string.

---------

Co-authored-by: Peter Sobot <psobot@gmail.com>
Co-authored-by: Peter Sobot <psobot@spotify.com>

Author: sarmentow

.github/workflows/all.yml

@@ -74,7 +74,8 @@ jobs:
           && sudo apt-get install -y pkg-config libsndfile1 \
           libx11-dev libxrandr-dev libxinerama-dev \
           libxrender-dev libxcomposite-dev libxcb-xinerama0-dev \
-          libxcursor-dev libfreetype6 libfreetype6-dev
+          libxcursor-dev libfreetype6 libfreetype6-dev \
+          libasound2-dev
       # We depend on ccache features that are only present in 4.8.0 and later, but installing from apt-get gives us v3.
       - name: Install ccache on Linux
         if: runner.os == 'Linux'
@@ -257,7 +258,8 @@ jobs:
           && sudo apt-get install -y pkg-config libsndfile1 \
           libx11-dev libxrandr-dev libxinerama-dev \
           libxrender-dev libxcomposite-dev libxcb-xinerama0-dev \
-          libxcursor-dev libfreetype6 libfreetype6-dev
+          libxcursor-dev libfreetype6 libfreetype6-dev \
+          libasound2-dev
       # We depend on ccache features that are only present in 4.8.0 and later, but installing from apt-get gives us v3.
       - name: Install ccache on Linux
         if: runner.os == 'Linux'
@@ -363,7 +365,8 @@ jobs:
           && sudo apt-get install -y pkg-config libsndfile1 \
           libx11-dev libxrandr-dev libxinerama-dev \
           libxrender-dev libxcomposite-dev libxcb-xinerama0-dev \
-          libxcursor-dev libfreetype6 libfreetype6-dev
+          libxcursor-dev libfreetype6 libfreetype6-dev \
+          libasound2-dev
       # We depend on ccache features that are only present in 4.8.0 and later, but installing from apt-get gives us v3.
       - name: Install ccache on Linux
         if: runner.os == 'Linux'
@@ -431,6 +434,11 @@ jobs:
           GCS_ASSET_BUCKET_NAME: ${{ secrets.GCS_ASSET_BUCKET_NAME }}
           GCS_READER_SERVICE_ACCOUNT_KEY: ${{ secrets.GCS_READER_SERVICE_ACCOUNT_KEY }}
         run: python ./tests/download_test_plugins.py
+      - name: Setup dummy soundcard for testing
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-get install -y linux-modules-extra-$(uname -r)
+          sudo modprobe snd-dummy
       - name: Run tests
         env:
           TEST_WORKER_INDEX: ${{ matrix.runner_index }}
@@ -482,7 +490,8 @@ jobs:
           && sudo apt-get install -y pkg-config libsndfile1 \
           libx11-dev libxrandr-dev libxinerama-dev \
           libxrender-dev libxcomposite-dev libxcb-xinerama0-dev \
-          libxcursor-dev libfreetype6 libfreetype6-dev
+          libxcursor-dev libfreetype6 libfreetype6-dev \
+          libasound2-dev
       # We depend on ccache features that are only present in 4.8.0 and later, but installing from apt-get gives us v3.
       - name: Install ccache on Linux
         if: runner.os == 'Linux'
@@ -613,7 +622,8 @@ jobs:
           && sudo apt-get install -y pkg-config libsndfile1 \
           libx11-dev libxrandr-dev libxinerama-dev \
           libxrender-dev libxcomposite-dev libxcb-xinerama0-dev \
-          libxcursor-dev libfreetype6 libfreetype6-dev
+          libxcursor-dev libfreetype6 libfreetype6-dev \
+          libasound2-dev
       # We depend on ccache features that are only present in 4.8.0 and later, but installing from apt-get gives us v3.
       - name: Install ccache on Linux
         if: runner.os == 'Linux'

examples/add_reverb_to_file.py

@@ -31,7 +31,7 @@
 def get_num_frames(f: sf.SoundFile) -> int:
     # On some platforms and formats, f.frames == -1L.
     # Check for this bug and work around it:
-    if f.frames > 2 ** 32:
+    if len(f) > 2 ** 32:
         f.seek(0)
         last_position = f.tell()
         while True:
@@ -45,7 +45,7 @@ def get_num_frames(f: sf.SoundFile) -> int:
             else:
                 last_position = new_position
     else:
-        return f.frames
+        return len(f)
 
 
 def main():

examples/audio_monitoring_with_effects.py

@@ -0,0 +1,21 @@
+from pedalboard import Pedalboard, Compressor, Gain, Reverb
+from pedalboard.io import AudioStream
+
+# Open up an audio stream:
+stream = AudioStream(
+  input_device_name=AudioStream.input_device_names[0],
+  output_device_name=AudioStream.output_device_names[0],
+  num_input_channels=2,
+  num_output_channels=2,
+  allow_feedback=True,
+  buffer_size=128,
+  sample_rate=44100,
+) 
+
+stream.plugins = Pedalboard([
+  Reverb(wet_level=0.2),
+  Gain(1.0),
+  Compressor(),
+])
+
+stream.run()

pedalboard/JuceHeader.h

@@ -23,15 +23,12 @@
 #pragma once
 
 #include <juce_audio_basics/juce_audio_basics.h>
+#include <juce_audio_devices/juce_audio_devices.h>
 #include <juce_audio_formats/juce_audio_formats.h>
 #include <juce_audio_processors/juce_audio_processors.h>
 #include <juce_core/juce_core.h>
 #include <juce_data_structures/juce_data_structures.h>
 #include <juce_dsp/juce_dsp.h>
 #include <juce_events/juce_events.h>
 #include <juce_graphics/juce_graphics.h>
-#include <juce_gui_basics/juce_gui_basics.h>
-
-#ifndef JUCE_LINUX
-#include <juce_audio_devices/juce_audio_devices.h>
-#endif
+#include <juce_gui_basics/juce_gui_basics.h>

pedalboard/io/AudioStream.h

@@ -81,7 +81,10 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
           "`allow_feedback=True` to the AudioStream constructor.");
     }
 
-    if (!inputDeviceName && !outputDeviceName) {
+    if ((!inputDeviceName ||
+         (inputDeviceName.has_value() && inputDeviceName.value().empty())) &&
+        (!outputDeviceName ||
+         (outputDeviceName.has_value() && outputDeviceName.value().empty()))) {
       throw std::runtime_error("At least one of `input_device_name` or "
                                "`output_device_name` must be provided.");
     }
@@ -275,10 +278,14 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
     if (auto *type = deviceManager.getCurrentDeviceTypeObject()) {
       const auto info = getSetupInfo(setup, isInput);
 
-      if (numChannelsNeeded > 0 && info.name.isEmpty())
-        return {
+      if (numChannelsNeeded > 0 && info.name.isEmpty()) {
+        std::string deviceName =
             type->getDeviceNames(isInput)[type->getDefaultDeviceIndex(isInput)]
-                .toStdString()};
+                .toStdString();
+        if (!deviceName.empty()) {
+          return {deviceName};
+        }
+      }
     }
 #endif
     return {};
@@ -290,7 +297,7 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
                                      float **outputChannelData,
                                      int numOutputChannels, int numSamples) {
     // Live processing mode: run the input audio through a Pedalboard object.
-    if (!playBufferFifo && !recordBufferFifo) {
+    if (playBufferFifo && recordBufferFifo) {
       for (int i = 0; i < numOutputChannels; i++) {
         const float *inputChannel = inputChannelData[i % numInputChannels];
         std::memcpy((char *)outputChannelData[i], (char *)inputChannel,
@@ -314,9 +321,7 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
           }
         }
       }
-    }
-
-    if (recordBufferFifo) {
+    } else if (recordBufferFifo) {
       // If Python wants audio input, then copy the audio into the record
       // buffer:
       for (int attempt = 0; attempt < 2; attempt++) {
@@ -356,13 +361,12 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
           break;
         }
       }
-    }
-
-    for (int i = 0; i < numOutputChannels; i++) {
-      std::memset((char *)outputChannelData[i], 0, numSamples * sizeof(float));
-    }
+    } else if (playBufferFifo) {
+      for (int i = 0; i < numOutputChannels; i++) {
+        std::memset((char *)outputChannelData[i], 0,
+                    numSamples * sizeof(float));
+      }
 
-    if (playBufferFifo) {
       const auto scope = playBufferFifo->read(numSamples);
 
       if (scope.blockSize1 > 0)
@@ -378,6 +382,11 @@ class AudioStream : public std::enable_shared_from_this<AudioStream>
                       (char *)playBuffer->getReadPointer(i, scope.startIndex2),
                       scope.blockSize2 * sizeof(float));
         }
+    } else {
+      for (int i = 0; i < numOutputChannels; i++) {
+        std::memset((char *)outputChannelData[i], 0,
+                    numSamples * sizeof(float));
+      }
     }
   }
 
@@ -832,7 +841,7 @@ Or use :py:meth:`AudioStream.write` to stream audio in chunks::
 #ifdef JUCE_MODULE_AVAILABLE_juce_audio_devices
             return stream.getAudioDeviceSetup().bufferSize;
 #else
-            return 0;
+                                 return 0;
 #endif
           },
           "The size (in frames) of the buffer used between the audio "

pyproject.toml

@@ -14,10 +14,10 @@ build-backend = "setuptools.build_meta"
 
 # See: https://cibuildwheel.readthedocs.io/en/stable/options/#examples
 [tool.cibuildwheel.linux]
-before-all = "yum install -y libsndfile libX11-devel libXrandr-devel libXinerama-devel libXrender-devel libXcomposite-devel libXinerama-devel libXcursor-devel freetype-devel"
+before-all = "yum install -y libsndfile libX11-devel libXrandr-devel libXinerama-devel libXrender-devel libXcomposite-devel libXinerama-devel libXcursor-devel freetype-devel alsa-lib-devel"
 
 [[tool.cibuildwheel.overrides]]
 # Use apk instead of yum when building on Alpine Linux
 # (Note: this is experimental, as most VSTs require glibc and thus Alpine Linux isn't that useful)
 select = "*-musllinux*"
-before-all = "apk add libsndfile libx11-dev libxrandr-dev libxinerama-dev libxrender-dev libxcomposite-dev libxinerama-dev libxcursor-dev freetype-dev"
+before-all = "apk add libsndfile libx11-dev libxrandr-dev libxinerama-dev libxrender-dev libxcomposite-dev libxinerama-dev libxcursor-dev freetype-dev libexecinfo-dev alsa-lib-dev"

setup.py

@@ -52,6 +52,7 @@
         "-DJUCE_MODULE_AVAILABLE_juce_graphics=1",
         "-DJUCE_MODULE_AVAILABLE_juce_gui_basics=1",
         "-DJUCE_MODULE_AVAILABLE_juce_gui_extra=1",
+        "-DJUCE_MODULE_AVAILABLE_juce_audio_devices=1",
         "-DJUCE_GLOBAL_MODULE_SETTINGS_INCLUDED=1",
         "-DJUCE_STRICT_REFCOUNTEDPOINTER=1",
         "-DJUCE_STANDALONE_APPLICATION=1",
@@ -260,7 +261,6 @@ def ignore_files_matching(files, *matches):
         ALL_CPPFLAGS.append("-flto=thin")
         ALL_LINK_ARGS.append("-flto=thin")
     ALL_LINK_ARGS.append("-fvisibility=hidden")
-    ALL_CPPFLAGS.append("-DJUCE_MODULE_AVAILABLE_juce_audio_devices=1")
     ALL_CFLAGS += ["-Wno-comment"]
 elif platform.system() == "Linux":
     ALL_CPPFLAGS.append("-DLINUX=1")
@@ -272,7 +272,6 @@ def ignore_files_matching(files, *matches):
     ALL_CFLAGS += ["-Wno-comment"]
 elif platform.system() == "Windows":
     ALL_CPPFLAGS.append("-DWINDOWS=1")
-    ALL_CPPFLAGS.append("-DJUCE_MODULE_AVAILABLE_juce_audio_devices=1")
 else:
     raise NotImplementedError(
         "Not sure how to build JUCE on platform: {}!".format(platform.system())
@@ -356,6 +355,7 @@ def ignore_files_matching(files, *matches):
         include_paths = [flag[2:] for flag in flags]
         ALL_INCLUDES += include_paths
     ALL_LINK_ARGS += ["-lfreetype"]
+    ALL_LINK_ARGS += ["-lasound"]
 
     ALL_RESOLVED_SOURCE_PATHS = [str(p.resolve()) for p in ALL_SOURCE_PATHS]
 elif platform.system() == "Windows":

tests/test_audio_stream.py

@@ -14,7 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import platform
 import time
 
 import numpy as np
@@ -36,10 +35,9 @@
 
 
 # Note: this test may do nothing on CI, because we don't have mock audio devices available.
-# This will run on macOS and probably Windows as long as at least one audio device is available.
+# This will run on Linux, macOS and probably Windows as long as at least one audio device is available.
 @pytest.mark.parametrize("input_device_name", INPUT_DEVICE_NAMES)
 @pytest.mark.parametrize("output_device_name", pedalboard.io.AudioStream.output_device_names)
-@pytest.mark.skipif(platform.system() == "Linux", reason="AudioStream not supported on Linux yet.")
 def test_create_stream(input_device_name: str, output_device_name: str):
     try:
         stream = pedalboard.io.AudioStream(
@@ -69,11 +67,13 @@ def test_create_stream(input_device_name: str, output_device_name: str):
 
 
 # Note: this test may do nothing on CI, because we don't have mock audio devices available.
-# This will run on macOS and probably Windows as long as at least one audio device is available.
-@pytest.mark.skipif(platform.system() == "Linux", reason="AudioStream not supported on Linux yet.")
+# This will run on Linux, macOS and probably Windows as long as at least one audio device is available.
 @pytest.mark.skipif(
-    pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device",
-    reason="Tests do not work with a null audio device.",
+    (
+        pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device"
+        or pedalboard.io.AudioStream.default_output_device_name is None
+    ),
+    reason="Test requires a working audio device.",
 )
 def test_write_to_stream():
     try:
@@ -94,11 +94,13 @@ def test_write_to_stream():
 
 
 # Note: this test may do nothing on CI, because we don't have mock audio devices available.
-# This will run on macOS and probably Windows as long as at least one audio device is available.
-@pytest.mark.skipif(platform.system() == "Linux", reason="AudioStream not supported on Linux yet.")
+# This will run on Linux, macOS and probably Windows as long as at least one audio device is available.
 @pytest.mark.skipif(
-    pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device",
-    reason="Tests do not work with a null audio device.",
+    (
+        pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device"
+        or pedalboard.io.AudioStream.default_output_device_name is None
+    ),
+    reason="Test requires a working audio device.",
 )
 def test_write_to_stream_without_opening():
     try:
@@ -118,11 +120,13 @@ def test_write_to_stream_without_opening():
 
 
 # Note: this test may do nothing on CI, because we don't have mock audio devices available.
-# This will run on macOS and probably Windows as long as at least one audio device is available.
-@pytest.mark.skipif(platform.system() == "Linux", reason="AudioStream not supported on Linux yet.")
+# This will run on Linux, macOS and probably Windows as long as at least one audio device is available.
 @pytest.mark.skipif(
-    pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device",
-    reason="Tests do not work with a null audio device.",
+    (
+        pedalboard.io.AudioStream.default_input_device_name == "Null Audio Device"
+        or pedalboard.io.AudioStream.default_input_device_name is None
+    ),
+    reason="Test requires a working audio device.",
 )
 def test_read_from_stream():
     try:
@@ -141,11 +145,13 @@ def test_read_from_stream():
 
 
 # Note: this test may do nothing on CI, because we don't have mock audio devices available.
-# This will run on macOS and probably Windows as long as at least one audio device is available.
-@pytest.mark.skipif(platform.system() == "Linux", reason="AudioStream not supported on Linux yet.")
+# This will run on Linux, macOS and probably Windows as long as at least one audio device is available.
 @pytest.mark.skipif(
-    pedalboard.io.AudioStream.default_output_device_name == "Null Audio Device",
-    reason="Tests do not work with a null audio device.",
+    (
+        pedalboard.io.AudioStream.default_input_device_name == "Null Audio Device"
+        or pedalboard.io.AudioStream.default_input_device_name is None
+    ),
+    reason="Test requires a working audio device.",
 )
 def test_read_from_stream_measures_dropped_frames():
     try:
@@ -157,6 +163,8 @@ def test_read_from_stream_measures_dropped_frames():
 
     assert stream is not None
     with stream:
+        if stream.sample_rate == 0:
+            raise pytest.skip("Sample rate of default audio device is 0")
         assert stream.running
         assert stream.dropped_input_frame_count == 0
         time.sleep(5 * stream.buffer_size / stream.sample_rate)
@@ -168,9 +176,3 @@ def test_read_from_stream_measures_dropped_frames():
 
     # ...but we should still know how many frames were dropped:
     assert stream.dropped_input_frame_count == dropped_count
-
-
-@pytest.mark.skipif(platform.system() != "Linux", reason="Test platform is not Linux.")
-def test_create_stream_fails_on_linux():
-    with pytest.raises(RuntimeError):
-        pedalboard.io.AudioStream("input", "output")