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Piano: Use AudioServer instead of /dev/audio for audio

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Piano is an old application that predates AudioServer. For this reason,
it was architected to directly talk to the soundcard via the /dev/audio
device. This caused multiple problems including simultaneous playback
issues, no ability to change volume/mute for Piano and more.

This change moves Piano to use AudioServer like any well-behaved audio
application :^) The track processing and IPC communication is moved to
the main thread because IPC doesn't like multi-threading. For this, the
new AudioPlayerLoop class is utilized that should evolve into the
DSP->AudioServer interface in the future.

Because Piano's CPU utilization has gotten so low (about 3-6%), the UI
update loop is switched back to render at exactly 60fps.

This is an important commit on the road to #6528.
This commit is contained in:
kleines Filmröllchen 2021-07-05 14:48:59 +02:00 • committed by Andreas Kling
parent 9d00db618d
commit 9f1f3c6f37
2 changed files with 67 additions and 33 deletions
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98
Userland/Applications/Piano/main.cpp
View file

@ -9,10 +9,13 @@
#include "MainWidget.h"
#include "TrackManager.h"
#include <AK/Array.h>
#include <AK/Queue.h>
#include <LibAudio/Buffer.h>
#include <LibAudio/ClientConnection.h>
#include <LibAudio/WavWriter.h>
#include <LibCore/EventLoop.h>
#include <LibCore/File.h>
#include <LibCore/Object.h>
#include <LibGUI/Action.h>
#include <LibGUI/Application.h>
#include <LibGUI/FilePicker.h>
@ -23,6 +26,65 @@
#include <LibGfx/Bitmap.h>
#include <LibThreading/Thread.h>
// Converts Piano-internal data to an Audio::Buffer that AudioServer receives
static NonnullRefPtr<Audio::Buffer> music_samples_to_buffer(Array<Sample, sample_count> samples)
{
Vector<Audio::Frame, sample_count> frames;
frames.ensure_capacity(sample_count);
for (auto sample : samples) {
Audio::Frame frame = { sample.left / (double)NumericLimits<i16>::max(), sample.right / (double)NumericLimits<i16>::max() };
frames.unchecked_append(frame);
}
return Audio::Buffer::create_with_samples(frames);
}
// Wrapper class accepting custom events to advance the track playing and forward audio data to the system.
// This does not run on a separate thread, preventing IPC multithreading madness.
class AudioPlayerLoop : public Core::Object {
C_OBJECT(AudioPlayerLoop)
public:
AudioPlayerLoop(TrackManager& track_manager, bool& need_to_write_wav, Audio::WavWriter& wav_writer)
: m_track_manager(track_manager)
, m_need_to_write_wav(need_to_write_wav)
, m_wav_writer(wav_writer)
{
m_audio_client = Audio::ClientConnection::construct();
m_audio_client->on_finish_playing_buffer = [this](int buffer_id) {
(void)buffer_id;
enqueue_audio();
};
}
void enqueue_audio()
{
m_track_manager.fill_buffer(m_buffer);
NonnullRefPtr<Audio::Buffer> audio_buffer = music_samples_to_buffer(m_buffer);
m_audio_client->async_enqueue(audio_buffer);
// FIXME: This should be done somewhere else.
if (m_need_to_write_wav) {
m_need_to_write_wav = false;
m_track_manager.reset();
m_track_manager.set_should_loop(false);
do {
m_track_manager.fill_buffer(m_buffer);
m_wav_writer.write_samples(reinterpret_cast<u8*>(m_buffer.data()), buffer_size);
} while (m_track_manager.time());
m_track_manager.reset();
m_track_manager.set_should_loop(true);
m_wav_writer.finalize();
}
}
private:
TrackManager& m_track_manager;
Array<Sample, sample_count> m_buffer;
RefPtr<Audio::ClientConnection> m_audio_client;
bool& m_need_to_write_wav;
Audio::WavWriter& m_wav_writer;
};
int main(int argc, char** argv)
{
if (pledge("stdio thread rpath cpath wpath recvfd sendfd unix", nullptr) < 0) {
@ -32,8 +94,6 @@ int main(int argc, char** argv)
auto app = GUI::Application::construct(argc, argv);
auto audio_client = Audio::ClientConnection::construct();
TrackManager track_manager;
auto app_icon = GUI::Icon::default_icon("app-piano");
@ -48,37 +108,11 @@ int main(int argc, char** argv)
Optional<String> save_path;
bool need_to_write_wav = false;
auto audio_thread = Threading::Thread::construct([&] {
auto audio = Core::File::construct("/dev/audio");
if (!audio->open(Core::OpenMode::WriteOnly)) {
dbgln("Can't open audio device: {}", audio->error_string());
return 1;
}
auto audio_loop = AudioPlayerLoop::construct(track_manager, need_to_write_wav, wav_writer);
audio_loop->enqueue_audio();
audio_loop->enqueue_audio();
Array<Sample, sample_count> buffer;
while (!Core::EventLoop::current().was_exit_requested()) {
track_manager.fill_buffer(buffer);
audio->write(reinterpret_cast<u8*>(buffer.data()), buffer_size);
Core::EventLoop::wake();
if (need_to_write_wav) {
need_to_write_wav = false;
track_manager.reset();
track_manager.set_should_loop(false);
do {
track_manager.fill_buffer(buffer);
wav_writer.write_samples(reinterpret_cast<u8*>(buffer.data()), buffer_size);
} while (track_manager.time());
track_manager.reset();
track_manager.set_should_loop(true);
wav_writer.finalize();
}
}
return 0;
});
audio_thread->start();
auto main_widget_updater = Core::Timer::construct(150, [&] {
auto main_widget_updater = Core::Timer::construct(static_cast<int>((1 / 60.0) * 1000), [&] {
Core::EventLoop::current().post_event(main_widget, make<Core::CustomEvent>(0));
});
main_widget_updater->start();