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AWavLoader.cpp
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AWavLoader.cpp
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#include <AK/BufferStream.h>
#include <LibAudio/ABuffer.h>
#include <LibAudio/AWavLoader.h>
#include <LibCore/CFile.h>
#include <LibCore/CIODeviceStreamReader.h>
#include <limits>
AWavLoader::AWavLoader(const StringView& path)
: m_file(CFile::construct(path))
{
if (!m_file->open(CIODevice::ReadOnly)) {
m_error_string = String::format("Can't open file: %s", m_file->error_string());
return;
}
parse_header();
}
RefPtr<ABuffer> AWavLoader::get_more_samples(size_t max_bytes_to_read_from_input)
{
#ifdef AWAVLOADER_DEBUG
dbgprintf("Read WAV of format PCM with num_channels %u sample rate %u, bits per sample %u\n", m_num_channels, m_sample_rate, m_bits_per_sample);
#endif
auto raw_samples = m_file->read(max_bytes_to_read_from_input);
if (raw_samples.is_empty())
return nullptr;
auto buffer = ABuffer::from_pcm_data(raw_samples, m_num_channels, m_bits_per_sample, m_sample_rate);
m_loaded_samples += buffer->sample_count();
return buffer;
}
bool AWavLoader::parse_header()
{
CIODeviceStreamReader stream(*m_file);
#define CHECK_OK(msg) \
do { \
ASSERT(ok); \
if (stream.handle_read_failure()) { \
m_error_string = String::format("Premature stream EOF at %s", msg); \
return {}; \
} \
if (!ok) { \
m_error_string = String::format("Parsing failed: %s", msg); \
return {}; \
} else { \
dbgprintf("%s is OK!\n", msg); \
} \
} while (0);
bool ok = true;
u32 riff;
stream >> riff;
ok = ok && riff == 0x46464952; // "RIFF"
CHECK_OK("RIFF header");
u32 sz;
stream >> sz;
ok = ok && sz < 1024 * 1024 * 1024; // arbitrary
CHECK_OK("File size");
ASSERT(sz < 1024 * 1024 * 1024);
u32 wave;
stream >> wave;
ok = ok && wave == 0x45564157; // "WAVE"
CHECK_OK("WAVE header");
u32 fmt_id;
stream >> fmt_id;
ok = ok && fmt_id == 0x20746D66; // "FMT"
CHECK_OK("FMT header");
u32 fmt_size;
stream >> fmt_size;
ok = ok && fmt_size == 16;
CHECK_OK("FMT size");
ASSERT(fmt_size == 16);
u16 audio_format;
stream >> audio_format;
CHECK_OK("Audio format"); // incomplete read check
ok = ok && audio_format == 1; // WAVE_FORMAT_PCM
ASSERT(audio_format == 1);
CHECK_OK("Audio format"); // value check
stream >> m_num_channels;
ok = ok && (m_num_channels == 1 || m_num_channels == 2);
CHECK_OK("Channel count");
stream >> m_sample_rate;
CHECK_OK("Sample rate");
u32 byte_rate;
stream >> byte_rate;
CHECK_OK("Byte rate");
u16 block_align;
stream >> block_align;
CHECK_OK("Block align");
stream >> m_bits_per_sample;
CHECK_OK("Bits per sample"); // incomplete read check
ok = ok && (m_bits_per_sample == 8 || m_bits_per_sample == 16 || m_bits_per_sample == 24);
ASSERT(m_bits_per_sample == 8 || m_bits_per_sample == 16 || m_bits_per_sample == 24);
CHECK_OK("Bits per sample"); // value check
// Read chunks until we find DATA
bool found_data = false;
u32 data_sz = 0;
while (true) {
u32 chunk_id;
stream >> chunk_id;
CHECK_OK("Reading chunk ID searching for data");
stream >> data_sz;
CHECK_OK("Reading chunk size searching for data");
if (chunk_id == 0x61746164) { // DATA
found_data = true;
break;
}
}
ok = ok && found_data;
CHECK_OK("Found no data chunk");
ASSERT(found_data);
ok = ok && data_sz < INT32_MAX;
CHECK_OK("Data was too large");
int bytes_per_sample = (m_bits_per_sample / 8) * m_num_channels;
m_total_samples = data_sz / bytes_per_sample;
// Just make sure we're good before we read the data...
ASSERT(!stream.handle_read_failure());
return true;
}
// 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);
bool read_sample();
void prepare();
private:
const float m_ratio;
float m_current_ratio { 0 };
};
AResampleHelper::AResampleHelper(float source, float target)
: m_ratio(source / target)
{
}
void AResampleHelper::prepare()
{
m_current_ratio += m_ratio;
}
bool AResampleHelper::read_sample()
{
if (m_current_ratio > 1) {
m_current_ratio--;
return true;
}
return false;
}
template<typename SampleReader>
static void read_samples_from_stream(BufferStream& stream, SampleReader read_sample, Vector<ASample>& samples, int num_channels, int source_rate)
{
AResampleHelper resampler(source_rate, 44100);
float norm_l = 0;
float norm_r = 0;
switch (num_channels) {
case 1:
while (!stream.handle_read_failure()) {
resampler.prepare();
while (resampler.read_sample()) {
norm_l = read_sample(stream);
}
samples.append(ASample(norm_l));
}
break;
case 2:
while (!stream.handle_read_failure()) {
resampler.prepare();
while (resampler.read_sample()) {
norm_l = read_sample(stream);
norm_r = read_sample(stream);
}
samples.append(ASample(norm_l, norm_r));
}
break;
default:
ASSERT_NOT_REACHED();
}
}
static float read_norm_sample_24(BufferStream& stream)
{
u8 byte = 0;
stream >> byte;
u32 sample1 = byte;
stream >> byte;
u32 sample2 = byte;
stream >> byte;
u32 sample3 = byte;
i32 value = 0;
value = sample1 << 8;
value |= (sample2 << 16);
value |= (sample3 << 24);
return float(value) / std::numeric_limits<i32>::max();
}
static float read_norm_sample_16(BufferStream& stream)
{
i16 sample = 0;
stream >> sample;
return float(sample) / std::numeric_limits<i16>::max();
}
static float read_norm_sample_8(BufferStream& stream)
{
u8 sample = 0;
stream >> sample;
return float(sample) / std::numeric_limits<u8>::max();
}
// ### can't const this because BufferStream is non-const
// perhaps we need a reading class separate from the writing one, that can be
// entirely consted.
RefPtr<ABuffer> ABuffer::from_pcm_data(ByteBuffer& data, int num_channels, int bits_per_sample, int source_rate)
{
BufferStream stream(data);
Vector<ASample> fdata;
fdata.ensure_capacity(data.size() * 2);
#ifdef AWAVLOADER_DEBUG
dbg() << "Reading " << bits_per_sample << " bits and " << num_channels << " channels, total bytes: " << data.size();
#endif
switch (bits_per_sample) {
case 8:
read_samples_from_stream(stream, read_norm_sample_8, fdata, num_channels, source_rate);
break;
case 16:
read_samples_from_stream(stream, read_norm_sample_16, fdata, num_channels, source_rate);
break;
case 24:
read_samples_from_stream(stream, read_norm_sample_24, fdata, num_channels, source_rate);
break;
default:
ASSERT_NOT_REACHED();
}
// We should handle this in a better way above, but for now --
// just make sure we're good. Worst case we just write some 0s where they
// don't belong.
ASSERT(!stream.handle_read_failure());
// HACK: This is a total hack to remove an unnecessary sample at the end of the buffer.
// FIXME: Don't generate the extra sample... :^)
for (int i = 0; i < 1; ++i)
fdata.take_last();
return ABuffer::create_with_samples(move(fdata));
}