ladybird/Libraries/LibAudio/ABuffer.h
Till Mayer 4c8341d080 LibAudio: Fixed stuttery playback of audio
When playing an ABuffer, the count of samples were determined by the
size of the SharedBuffer. This caused small pauses of up to 512
samples during the playback, when the size of the shared buffer was
rounded up to a multiple of 4096. This problem was amplified by the
fact that the AResampleHelper was created every time a new chunk of
audio was to be processed, causing inconsistencies in the playback of
wav files.
2019-10-16 16:25:38 +02:00

115 lines
2.9 KiB
C++

#pragma once
#include <AK/ByteBuffer.h>
#include <AK/Types.h>
#include <AK/Vector.h>
#include <LibC/SharedBuffer.h>
// A single sample in an audio buffer.
// Values are floating point, and should range from -1.0 to +1.0
struct ASample {
ASample()
: left(0)
, right(0)
{
}
// For mono
ASample(float left)
: left(left)
, right(left)
{
}
// For stereo
ASample(float left, float right)
: left(left)
, right(right)
{
}
void clip()
{
if (left > 1)
left = 1;
else if (left < -1)
left = -1;
if (right > 1)
right = 1;
else if (right < -1)
right = -1;
}
void scale(int percent)
{
float pct = (float)percent / 100.0;
left *= pct;
right *= pct;
}
ASample& operator+=(const ASample& other)
{
left += other.left;
right += other.right;
return *this;
}
float left;
float right;
};
// Small helper to resample from one playback rate to another
// This isn't really "smart", in that we just insert (or drop) samples.
// Should do better...
class AResampleHelper {
public:
AResampleHelper(float source, float target);
void process_sample(float sample_l, float sample_r);
bool read_sample(float& next_l, float& next_r);
private:
const float m_ratio;
float m_current_ratio { 0 };
float m_last_sample_l { 0 };
float m_last_sample_r { 0 };
};
// A buffer of audio samples, normalized to 44100hz.
class ABuffer : public RefCounted<ABuffer> {
public:
static RefPtr<ABuffer> from_pcm_data(ByteBuffer& data, AResampleHelper& resampler, int num_channels, int bits_per_sample);
static NonnullRefPtr<ABuffer> create_with_samples(Vector<ASample>&& samples)
{
return adopt(*new ABuffer(move(samples)));
}
static NonnullRefPtr<ABuffer> create_with_shared_buffer(NonnullRefPtr<SharedBuffer>&& buffer, int sample_count)
{
return adopt(*new ABuffer(move(buffer), sample_count));
}
const ASample* samples() const { return (const ASample*)data(); }
int sample_count() const { return m_sample_count; }
const void* data() const { return m_buffer->data(); }
int size_in_bytes() const { return m_sample_count * (int)sizeof(ASample); }
int shared_buffer_id() const { return m_buffer->shared_buffer_id(); }
SharedBuffer& shared_buffer() { return *m_buffer; }
private:
explicit ABuffer(Vector<ASample>&& samples)
: m_buffer(*SharedBuffer::create_with_size(samples.size() * sizeof(ASample))),
m_sample_count(samples.size())
{
memcpy(m_buffer->data(), samples.data(), samples.size() * sizeof(ASample));
}
explicit ABuffer(NonnullRefPtr<SharedBuffer>&& buffer, int sample_count)
: m_buffer(move(buffer)),
m_sample_count(sample_count)
{
}
NonnullRefPtr<SharedBuffer> m_buffer;
const int m_sample_count;
};