ladybird/Userland/Utilities/aplay.cpp
kleines Filmröllchen 49b087f3cd LibAudio+Userland: Use new audio queue in client-server communication
Previously, we were sending Buffers to the server whenever we had new
audio data for it. This meant that for every audio enqueue action, we
needed to create a new shared memory anonymous buffer, send that
buffer's file descriptor over IPC (+recfd on the other side) and then
map the buffer into the audio server's memory to be able to play it.
This was fine for sending large chunks of audio data, like when playing
existing audio files. However, in the future we want to move to
real-time audio in some applications like Piano. This means that the
size of buffers that are sent need to be very small, as just the size of
a buffer itself is part of the audio latency. If we were to try
real-time audio with the existing system, we would run into problems
really quickly. Dealing with a continuous stream of new anonymous files
like the current audio system is rather expensive, as we need Kernel
help in multiple places. Additionally, every enqueue incurs an IPC call,
which are not optimized for >1000 calls/second (which would be needed
for real-time audio with buffer sizes of ~40 samples). So a fundamental
change in how we handle audio sending in userspace is necessary.

This commit moves the audio sending system onto a shared single producer
circular queue (SSPCQ) (introduced with one of the previous commits).
This queue is intended to live in shared memory and be accessed by
multiple processes at the same time. It was specifically written to
support the audio sending case, so e.g. it only supports a single
producer (the audio client). Now, audio sending follows these general
steps:
- The audio client connects to the audio server.
- The audio client creates a SSPCQ in shared memory.
- The audio client sends the SSPCQ's file descriptor to the audio server
  with the set_buffer() IPC call.
- The audio server receives the SSPCQ and maps it.
- The audio client signals start of playback with start_playback().
- At the same time:
  - The audio client writes its audio data into the shared-memory queue.
  - The audio server reads audio data from the shared-memory queue(s).
  Both sides have additional before-queue/after-queue buffers, depending
  on the exact application.
- Pausing playback is just an IPC call, nothing happens to the buffer
  except that the server stops reading from it until playback is
  resumed.
- Muting has nothing to do with whether audio data is read or not.
- When the connection closes, the queues are unmapped on both sides.

This should already improve audio playback performance in a bunch of
places.

Implementation & commit notes:
- Audio loaders don't create LegacyBuffers anymore. LegacyBuffer is kept
  for WavLoader, see previous commit message.
- Most intra-process audio data passing is done with FixedArray<Sample>
  or Vector<Sample>.
- Improvements to most audio-enqueuing applications. (If necessary I can
  try to extract some of the aplay improvements.)
- New APIs on LibAudio/ClientConnection which allows non-realtime
  applications to enqueue audio in big chunks like before.
- Removal of status APIs from the audio server connection for
  information that can be directly obtained from the shared queue.
- Split the pause playback API into two APIs with more intuitive names.

I know this is a large commit, and you can kinda tell from the commit
message. It's basically impossible to break this up without hacks, so
please forgive me. These are some of the best changes to the audio
subsystem and I hope that that makes up for this :yaktangle: commit.

:yakring:
2022-04-21 13:55:00 +02:00

129 lines
5.3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021-2022, kleines Filmröllchen <filmroellchen@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Types.h>
#include <LibAudio/ConnectionFromClient.h>
#include <LibAudio/Loader.h>
#include <LibAudio/Resampler.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/EventLoop.h>
#include <LibCore/System.h>
#include <LibMain/Main.h>
#include <math.h>
#include <stdio.h>
// The Kernel has issues with very large anonymous buffers.
// FIXME: This appears to be fine for now, but it's really a hack.
constexpr size_t LOAD_CHUNK_SIZE = 128 * KiB;
ErrorOr<int> serenity_main(Main::Arguments arguments)
{
TRY(Core::System::pledge("stdio rpath sendfd unix thread"));
char const* path = nullptr;
bool should_loop = false;
bool show_sample_progress = false;
Core::ArgsParser args_parser;
args_parser.add_positional_argument(path, "Path to audio file", "path");
args_parser.add_option(should_loop, "Loop playback", "loop", 'l');
args_parser.add_option(show_sample_progress, "Show playback progress in samples", "sample-progress", 's');
args_parser.parse(arguments);
TRY(Core::System::unveil(Core::File::absolute_path(path), "r"));
TRY(Core::System::unveil("/tmp/portal/audio", "rw"));
TRY(Core::System::unveil(nullptr, nullptr));
Core::EventLoop loop;
auto audio_client = TRY(Audio::ConnectionFromClient::try_create());
auto maybe_loader = Audio::Loader::create(path);
if (maybe_loader.is_error()) {
warnln("Failed to load audio file: {}", maybe_loader.error().description);
return 1;
}
auto loader = maybe_loader.release_value();
TRY(Core::System::pledge("stdio sendfd thread"));
outln("\033[34;1m Playing\033[0m: {}", path);
outln("\033[34;1m Format\033[0m: {} {} Hz, {}-bit, {}",
loader->format_name(),
loader->sample_rate(),
loader->bits_per_sample(),
loader->num_channels() == 1 ? "Mono" : "Stereo");
out("\033[34;1mProgress\033[0m: \033[s");
auto resampler = Audio::ResampleHelper<Audio::Sample>(loader->sample_rate(), audio_client->get_sample_rate());
// If we're downsampling, we need to appropriately load more samples at once.
size_t const load_size = static_cast<size_t>(LOAD_CHUNK_SIZE * static_cast<double>(loader->sample_rate()) / static_cast<double>(audio_client->get_sample_rate()));
// We assume that the loader can load samples at at least 2x speed (testing confirms 9x-12x for FLAC, 14x for WAV).
// Therefore, when the server-side buffer can only play as long as the time it takes us to load a chunk,
// we give it new data.
unsigned const min_buffer_size = load_size / 2;
auto print_playback_update = [&]() {
out("\033[u");
if (show_sample_progress) {
out("{}/{}", audio_client->total_played_samples(), loader->total_samples());
} else {
auto playing_seconds = static_cast<int>(floor(static_cast<double>(audio_client->total_played_samples()) / static_cast<double>(loader->sample_rate())));
auto playing_minutes = playing_seconds / 60;
auto playing_seconds_of_minute = playing_seconds % 60;
auto total_seconds = static_cast<int>(floor(static_cast<double>(loader->total_samples()) / static_cast<double>(loader->sample_rate())));
auto total_minutes = total_seconds / 60;
auto total_seconds_of_minute = total_seconds % 60;
auto remaining_seconds = total_seconds - playing_seconds;
auto remaining_minutes = remaining_seconds / 60;
auto remaining_seconds_of_minute = remaining_seconds % 60;
out("\033[1m{:02d}:{:02d}\033[0m [{}{:02d}:{:02d}] -- {:02d}:{:02d}",
playing_minutes, playing_seconds_of_minute,
remaining_seconds == 0 ? " " : "-",
remaining_minutes, remaining_seconds_of_minute,
total_minutes, total_seconds_of_minute);
}
fflush(stdout);
};
for (;;) {
auto samples = loader->get_more_samples(load_size);
if (!samples.is_error()) {
if (samples.value().size() > 0) {
print_playback_update();
// We can read and enqueue more samples
resampler.reset();
auto resampled_samples = resampler.resample(move(samples.value()));
TRY(audio_client->async_enqueue(move(resampled_samples)));
} else if (should_loop) {
// We're done: now loop
auto result = loader->reset();
if (result.is_error()) {
outln();
outln("Error while resetting: {} (at {:x})", result.error().description, result.error().index);
}
} else if (samples.value().size() == 0 && audio_client->remaining_samples() == 0) {
// We're done and the server is done
break;
}
while (audio_client->remaining_samples() > min_buffer_size) {
// The server has enough data for now
print_playback_update();
usleep(1'000'000 / 10);
}
} else {
outln();
outln("Error: {} (at {:x})", samples.error().description, samples.error().index);
return 1;
}
}
outln();
return 0;
}