
This implementation is very naive compared to the PulseAudio one. Instead of using a callback implemented by the audio server connection to push audio to the buffer, we have to poll on a timer to check when we need to push the audio buffers. Implementing cross-process condition variables into the audio queue class could allow us to avoid polling, which may prove beneficial to CPU usage. Audio timestamps will be accurate to the number of samples available, but will count in increments of about 100ms and run ahead of the actual audio being pushed to the device by the server. Buffer underruns are completely ignored for now as well, since the `AudioServer` has no way to know how many samples are actually written in a single audio buffer.
92 lines
3.4 KiB
C++
92 lines
3.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Concepts.h>
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#include <AK/FixedArray.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/OwnPtr.h>
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#include <LibAudio/Queue.h>
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#include <LibAudio/UserSampleQueue.h>
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#include <LibCore/EventLoop.h>
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#include <LibCore/EventReceiver.h>
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#include <LibIPC/ConnectionToServer.h>
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#include <LibThreading/Mutex.h>
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#include <LibThreading/Thread.h>
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#include <Userland/Services/AudioServer/AudioClientEndpoint.h>
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#include <Userland/Services/AudioServer/AudioServerEndpoint.h>
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namespace Audio {
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class ConnectionToServer final
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: public IPC::ConnectionToServer<AudioClientEndpoint, AudioServerEndpoint>
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, public AudioClientEndpoint {
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IPC_CLIENT_CONNECTION(ConnectionToServer, "/tmp/session/%sid/portal/audio"sv)
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public:
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virtual ~ConnectionToServer() override;
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// Both of these APIs are for convenience and when you don't care about real-time behavior.
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// They will not work properly in conjunction with realtime_enqueue.
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// If you don't refill the buffer in time with this API, the last shared buffer write is zero-padded to play all of the samples.
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template<ArrayLike<Sample> Samples>
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ErrorOr<void> async_enqueue(Samples&& samples)
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{
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return async_enqueue(TRY(FixedArray<Sample>::create(samples.span())));
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}
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ErrorOr<void> async_enqueue(FixedArray<Sample>&& samples);
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void clear_client_buffer();
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// Returns immediately with the appropriate status if the buffer is full; use in conjunction with remaining_buffers to get low latency.
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ErrorOr<void, AudioQueue::QueueStatus> realtime_enqueue(Array<Sample, AUDIO_BUFFER_SIZE> samples);
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ErrorOr<void> blocking_realtime_enqueue(Array<Sample, AUDIO_BUFFER_SIZE> samples, Function<void()> wait_function);
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// This information can be deducted from the shared audio buffer.
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unsigned total_played_samples() const;
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// How many samples remain in m_enqueued_samples.
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unsigned remaining_samples();
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// How many buffers (i.e. short sample arrays) the server hasn't played yet.
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// Non-realtime code needn't worry about this.
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size_t remaining_buffers() const;
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// Whether there is room in the realtime audio queue for another sample buffer.
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bool can_enqueue() const;
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void set_self_sample_rate(u32 sample_rate);
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virtual void die() override;
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Function<void(double volume)> on_client_volume_change;
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private:
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ConnectionToServer(NonnullOwnPtr<Core::LocalSocket>);
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virtual void client_volume_changed(double) override;
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// We use this to perform the audio enqueuing on the background thread's event loop
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virtual void custom_event(Core::CustomEvent&) override;
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void update_good_sleep_time();
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// Shared audio buffer: both server and client constantly read and write to/from this.
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// This needn't be mutex protected: it's internally multi-threading aware.
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OwnPtr<AudioQueue> m_buffer;
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// The queue of non-realtime audio provided by the user.
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NonnullOwnPtr<UserSampleQueue> m_user_queue;
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NonnullRefPtr<Threading::Thread> m_background_audio_enqueuer;
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Core::EventLoop* m_enqueuer_loop { nullptr };
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Threading::Mutex m_enqueuer_loop_destruction;
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// A good amount of time to sleep when the queue is full.
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// (Only used for non-realtime enqueues)
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timespec m_good_sleep_time {};
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};
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}
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