ladybird/Libraries/LibMedia/Sinks/AudioMixingSink.cpp

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/*
* Copyright (c) 2025, Gregory Bertilson <gregory@ladybird.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Time.h>
#include <LibMedia/Audio/PlaybackStream.h>
#include <LibMedia/Providers/AudioDataProvider.h>
#include "AudioMixingSink.h"
namespace Media {
ErrorOr<NonnullRefPtr<AudioMixingSink>> AudioMixingSink::try_create()
{
auto weak_ref = TRY(try_make_ref_counted<AudioMixingSinkWeakReference>());
auto sink = TRY(try_make_ref_counted<AudioMixingSink>(weak_ref));
weak_ref->emplace(sink);
return sink;
}
AudioMixingSink::AudioMixingSink(AudioMixingSinkWeakReference& weak_ref)
: m_main_thread_event_loop(Core::EventLoop::current())
, m_weak_self(weak_ref)
{
}
AudioMixingSink::~AudioMixingSink()
{
m_weak_self->revoke();
}
void AudioMixingSink::deferred_create_playback_stream(Track const& track)
{
m_main_thread_event_loop.deferred_invoke([weak_self = m_weak_self, track = track] {
auto self = weak_self->take_strong();
if (self == nullptr)
return;
auto optional_track_mixing_data = self->m_track_mixing_datas.get(track);
if (!optional_track_mixing_data.has_value())
return;
Threading::MutexLocker locker { self->m_mutex };
auto& track_mixing_data = optional_track_mixing_data.release_value();
if (track_mixing_data.current_block.is_empty())
track_mixing_data.current_block = track_mixing_data.provider->retrieve_block();
if (!track_mixing_data.current_block.is_empty()) {
self->create_playback_stream(track_mixing_data.current_block.sample_rate(), track_mixing_data.current_block.channel_count());
return;
}
self->deferred_create_playback_stream(track);
});
}
void AudioMixingSink::set_provider(Track const& track, RefPtr<AudioDataProvider> const& provider)
{
Threading::MutexLocker locker { m_mutex };
m_track_mixing_datas.remove(track);
if (provider == nullptr)
return;
m_track_mixing_datas.set(track, TrackMixingData(*provider));
deferred_create_playback_stream(track);
}
RefPtr<AudioDataProvider> AudioMixingSink::provider(Track const& track) const
{
auto mixing_data = m_track_mixing_datas.get(track);
if (!mixing_data.has_value())
return nullptr;
return mixing_data->provider;
}
void AudioMixingSink::create_playback_stream(u32 sample_rate, u32 channel_count)
{
if (m_playback_stream_sample_rate >= sample_rate && m_playback_stream_channel_count >= channel_count) {
VERIFY(m_playback_stream);
return;
}
auto callback = [=, weak_self = m_weak_self](Bytes buffer, Audio::PcmSampleFormat format, size_t sample_count) -> ReadonlyBytes {
auto self = weak_self->take_strong();
if (!self)
return buffer.trim(0);
VERIFY(format == Audio::PcmSampleFormat::Float32);
VERIFY(!Checked<i64>::multiplication_would_overflow(sample_count, channel_count));
auto float_buffer_count = static_cast<i64>(sample_count) * channel_count;
auto float_buffer_size = float_buffer_count * sizeof(float);
VERIFY(buffer.size() >= float_buffer_size);
auto float_buffer = buffer.reinterpret<float>();
float_buffer.fill(0.0f);
Threading::MutexLocker mixing_data_locker { self->m_mutex };
if (sample_rate != self->m_playback_stream_sample_rate || channel_count != self->m_playback_stream_channel_count)
return buffer.trim(0);
auto buffer_start = self->m_next_sample_to_write.load();
for (auto& [track, track_data] : self->m_track_mixing_datas) {
auto next_sample = buffer_start;
auto samples_end = next_sample + static_cast<i64>(sample_count);
auto go_to_next_block = [&] {
auto new_block = track_data.provider->retrieve_block();
if (new_block.is_empty())
return false;
track_data.current_block = move(new_block);
return true;
};
if (track_data.current_block.is_empty()) {
if (!go_to_next_block())
continue;
}
while (!track_data.current_block.is_empty()) {
auto& current_block = track_data.current_block;
auto current_block_data_count = static_cast<i64>(current_block.data_count());
auto current_block_sample_count = static_cast<i64>(current_block.sample_count());
if (current_block.sample_rate() != sample_rate || current_block.channel_count() != channel_count) {
current_block.clear();
continue;
}
auto first_sample_offset = current_block.timestamp_in_samples();
if (first_sample_offset >= samples_end)
break;
auto block_end = first_sample_offset + current_block_sample_count;
if (block_end <= next_sample) {
if (!go_to_next_block())
break;
continue;
}
next_sample = max(next_sample, first_sample_offset);
auto index_in_block = (next_sample - first_sample_offset) * channel_count;
VERIFY(index_in_block < current_block_data_count);
auto index_in_buffer = (next_sample - buffer_start) * channel_count;
VERIFY(index_in_buffer < float_buffer_count);
auto write_count = current_block_data_count - index_in_block;
write_count = min(write_count, float_buffer_count - index_in_buffer);
VERIFY(write_count > 0);
VERIFY(index_in_buffer + write_count <= float_buffer_count);
VERIFY(write_count % channel_count == 0);
for (i64 i = 0; i < write_count; i++)
float_buffer[index_in_buffer + i] += current_block.data()[index_in_block + i];
auto write_end = index_in_block + write_count;
if (write_end == current_block_data_count) {
if (!go_to_next_block())
break;
continue;
}
VERIFY(write_end < current_block_data_count);
next_sample += write_count / channel_count;
if (next_sample == samples_end)
break;
VERIFY(next_sample < samples_end);
}
}
self->m_next_sample_to_write += static_cast<i64>(sample_count);
return buffer.slice(0, float_buffer_size);
};
constexpr u32 target_latency_ms = 100;
m_playback_stream = MUST(Audio::PlaybackStream::create(Audio::OutputState::Suspended, sample_rate, channel_count, target_latency_ms, move(callback)));
m_playback_stream_sample_rate = sample_rate;
m_playback_stream_channel_count = channel_count;
if (m_playing)
resume();
set_volume(m_volume);
}
AK::Duration AudioMixingSink::current_time() const
{
if (m_temporary_time.has_value())
return m_temporary_time.value();
if (!m_playback_stream)
return m_last_media_time;
auto time = m_last_media_time + (m_playback_stream->total_time_played() - m_last_stream_time);
auto max_time = AK::Duration::from_time_units(m_next_sample_to_write.load(MemoryOrder::memory_order_acquire), 1, m_playback_stream_sample_rate);
time = min(time, max_time);
return time;
}
void AudioMixingSink::resume()
{
m_playing = true;
if (!m_playback_stream)
return;
m_playback_stream->resume()
->when_resolved([weak_self = m_weak_self, &playback_stream = *m_playback_stream](auto new_device_time) {
auto self = weak_self->take_strong();
if (!self)
return;
if (self->m_playback_stream != &playback_stream)
return;
self->m_main_thread_event_loop.deferred_invoke([self, new_device_time]() {
self->m_last_stream_time = new_device_time;
});
})
.when_rejected([](auto&& error) {
warnln("Unexpected error while resuming AudioMixingSink: {}", error.string_literal());
});
}
void AudioMixingSink::pause()
{
m_playing = false;
if (!m_playback_stream)
return;
m_playback_stream->drain_buffer_and_suspend()
->when_resolved([weak_self = m_weak_self, &playback_stream = *m_playback_stream]() {
auto self = weak_self->take_strong();
if (!self)
return;
if (self->m_playback_stream != &playback_stream)
return;
auto new_stream_time = self->m_playback_stream->total_time_played();
auto new_media_time = AK::Duration::from_time_units(self->m_next_sample_to_write, 1, self->m_playback_stream_sample_rate);
self->m_main_thread_event_loop.deferred_invoke([self, new_stream_time, new_media_time]() {
self->m_last_stream_time = new_stream_time;
self->m_last_media_time = new_media_time;
});
})
.when_rejected([](auto&& error) {
warnln("Unexpected error while pausing AudioMixingSink: {}", error.string_literal());
});
}
void AudioMixingSink::set_time(AK::Duration time)
{
m_temporary_time = time;
m_playback_stream->drain_buffer_and_suspend()
->when_resolved([weak_self = m_weak_self, &playback_stream = *m_playback_stream, time]() {
auto self = weak_self->take_strong();
if (!self)
return;
if (self->m_playback_stream != &playback_stream)
return;
auto new_stream_time = self->m_playback_stream->total_time_played();
self->m_main_thread_event_loop.deferred_invoke([self, new_stream_time, time]() {
{
self->m_last_stream_time = new_stream_time;
self->m_last_media_time = time;
self->m_temporary_time = {};
{
Threading::MutexLocker mixing_locker { self->m_mutex };
self->m_next_sample_to_write = time.to_time_units(1, self->m_playback_stream_sample_rate);
}
for (auto& [track, track_data] : self->m_track_mixing_datas)
track_data.current_block.clear();
}
if (self->m_playing)
self->resume();
});
})
.when_rejected([](auto&& error) {
warnln("Unexpected error while setting time on AudioMixingSink: {}", error.string_literal());
});
}
void AudioMixingSink::set_volume(double volume)
{
m_volume = volume;
if (m_playback_stream) {
m_playback_stream->set_volume(m_volume)
->when_rejected([](Error&&) {
// FIXME: Do we even need this function to return a promise?
});
}
}
}