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serenity/Userland/Libraries/LibAudio/Loader.h
Nick Miller 23d5b99fbf LibAudio: Make Loader::seek() treat its input as a sample index
This fixes a bug where if you try to play a Wave file a second
time (or loop with `aplay -l`), the second time will be pure
noise.

The function `Audio::Loader::seek` is meant to seek to a specific
audio sample, e.g. seek(0) should go to the first audio sample.
However, WavLoader was interpreting seek(0) as the beginning
of the file or stream, which contains non-audio header data.

This fixes the bug by capturing the byte offset of the start of the
audio data, and offseting the raw file/stream seek by that amount.
2021-06-09 17:30:08 +04:30

76 lines
2.4 KiB
C++

/*
* Copyright (c) 2018-2021, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteBuffer.h>
#include <AK/RefCounted.h>
#include <AK/RefPtr.h>
#include <AK/StringView.h>
#include <LibAudio/Buffer.h>
#include <LibCore/File.h>
namespace Audio {
class LoaderPlugin {
public:
virtual ~LoaderPlugin() { }
virtual bool sniff() = 0;
virtual bool has_error() { return false; }
virtual const char* error_string() { return ""; }
virtual RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) = 0;
virtual void reset() = 0;
virtual void seek(const int sample_index) = 0;
virtual int loaded_samples() = 0;
virtual int total_samples() = 0;
virtual u32 sample_rate() = 0;
virtual u16 num_channels() = 0;
virtual PcmSampleFormat pcm_format() = 0;
virtual RefPtr<Core::File> file() = 0;
};
class Loader : public RefCounted<Loader> {
public:
static NonnullRefPtr<Loader> create(const StringView& path) { return adopt_ref(*new Loader(path)); }
static NonnullRefPtr<Loader> create(const ByteBuffer& buffer) { return adopt_ref(*new Loader(buffer)); }
bool has_error() const { return m_plugin ? m_plugin->has_error() : true; }
const char* error_string() const { return m_plugin ? m_plugin->error_string() : "No loader plugin available"; }
RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) const { return m_plugin ? m_plugin->get_more_samples(max_bytes_to_read_from_input) : nullptr; }
void reset() const
{
if (m_plugin)
m_plugin->reset();
}
void seek(const int position) const
{
if (m_plugin)
m_plugin->seek(position);
}
int loaded_samples() const { return m_plugin ? m_plugin->loaded_samples() : 0; }
int total_samples() const { return m_plugin ? m_plugin->total_samples() : 0; }
u32 sample_rate() const { return m_plugin ? m_plugin->sample_rate() : 0; }
u16 num_channels() const { return m_plugin ? m_plugin->num_channels() : 0; }
u16 bits_per_sample() const { return m_plugin ? pcm_bits_per_sample(m_plugin->pcm_format()) : 0; }
RefPtr<Core::File> file() const { return m_plugin ? m_plugin->file() : nullptr; }
private:
Loader(const StringView& path);
Loader(const ByteBuffer& buffer);
mutable OwnPtr<LoaderPlugin> m_plugin;
};
}