2013-12-25 08:59:10 +01:00
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <algorithm>
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2013-12-29 00:25:58 +01:00
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#include <alsa/asoundlib.h>
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2013-12-25 08:59:10 +01:00
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#include "SoftFM.h"
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#include "AudioOutput.h"
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using namespace std;
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/* **************** class AudioOutput **************** */
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// Encode a list of samples as signed 16-bit little-endian integers.
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void AudioOutput::samplesToInt16(const SampleVector& samples,
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vector<uint8_t>& bytes)
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{
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bytes.resize(2 * samples.size());
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SampleVector::const_iterator i = samples.begin();
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SampleVector::const_iterator n = samples.end();
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vector<uint8_t>::iterator k = bytes.begin();
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while (i != n) {
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Sample s = *(i++);
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s = max(Sample(-1.0), min(Sample(1.0), s));
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long v = lrint(s * 32767);
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unsigned long u = v;
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*(k++) = u & 0xff;
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*(k++) = (u >> 8) & 0xff;
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}
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}
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/* **************** class RawAudioOutput **************** */
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// Construct raw audio writer.
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RawAudioOutput::RawAudioOutput(const string& filename)
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{
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if (filename == "-") {
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m_fd = STDOUT_FILENO;
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} else {
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m_fd = open(filename.c_str(), O_WRONLY | O_CREAT | O_TRUNC, 0666);
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if (m_fd < 0) {
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m_error = "can not open '" + filename + "' (" +
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strerror(errno) + ")";
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m_zombie = true;
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return;
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}
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}
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}
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// Destructor.
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RawAudioOutput::~RawAudioOutput()
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{
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// Close file descriptor.
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if (m_fd >= 0 && m_fd != STDOUT_FILENO) {
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close(m_fd);
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}
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}
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// Write audio data.
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bool RawAudioOutput::write(const SampleVector& samples)
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{
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if (m_fd < 0)
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return -1;
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// Convert samples to bytes.
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samplesToInt16(samples, m_bytebuf);
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// Write data.
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size_t p = 0;
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size_t n = m_bytebuf.size();
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while (p < n) {
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ssize_t k = ::write(m_fd, m_bytebuf.data() + p, n - p);
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if (k <= 0) {
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if (k == 0 || errno != EINTR) {
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m_error = "write failed (";
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m_error += strerror(errno);
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m_error += ")";
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return false;
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}
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} else {
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p += k;
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}
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}
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return true;
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}
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#if 0
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/** Write audio data as .WAV file. */
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class WavAudioOutput
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{
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public:
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/**
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* Construct .WAV writer.
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*
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* filename :: file name (including path) or "-" to write to stdout
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* samplerate :: audio sample rate in Hz
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* stereo :: true if the output stream contains stereo data
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*/
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WavAudioOutput(const std::string& filename,
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unsigned int samplerate,
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bool stereo);
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~WavAudioOutput();
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bool write(const SampleVector& samples);
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std::string error();
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private:
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// TODO
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};
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2013-12-29 00:25:58 +01:00
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#endif
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/* **************** class AlsaAudioOutput **************** */
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2013-12-25 08:59:10 +01:00
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2013-12-29 00:25:58 +01:00
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// Construct ALSA output stream.
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AlsaAudioOutput::AlsaAudioOutput(const std::string& devname,
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unsigned int samplerate,
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bool stereo)
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2013-12-25 08:59:10 +01:00
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{
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2013-12-29 00:25:58 +01:00
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m_pcm = NULL;
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m_nchannels = stereo ? 2 : 1;
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2013-12-25 08:59:10 +01:00
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2013-12-29 00:25:58 +01:00
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int r = snd_pcm_open(&m_pcm, devname.c_str(),
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SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);
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2013-12-25 08:59:10 +01:00
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2013-12-29 00:25:58 +01:00
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if (r < 0) {
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m_error = "can not open PCM device '" + devname + "' (" +
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strerror(-r) + ")";
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m_zombie = true;
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return;
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}
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2013-12-25 08:59:10 +01:00
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2013-12-29 00:25:58 +01:00
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snd_pcm_nonblock(m_pcm, 0);
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r = snd_pcm_set_params(m_pcm,
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SND_PCM_FORMAT_S16_LE,
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SND_PCM_ACCESS_RW_INTERLEAVED,
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m_nchannels,
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samplerate,
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1, // allow soft resampling
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500000); // latency in us
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if (r < 0) {
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m_error = "can not set PCM parameters (";
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m_error += strerror(-r);
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m_error += ")";
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m_zombie = true;
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}
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}
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// Destructor.
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AlsaAudioOutput::~AlsaAudioOutput()
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{
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// Close device.
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if (m_pcm != NULL) {
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snd_pcm_close(m_pcm);
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}
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}
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// Write audio data.
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bool AlsaAudioOutput::write(const SampleVector& samples)
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{
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if (m_zombie)
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return false;
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// Convert samples to bytes.
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samplesToInt16(samples, m_bytebuf);
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// Write data.
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unsigned int p = 0;
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unsigned int n = samples.size() / m_nchannels;
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unsigned int framesize = 2 * m_nchannels;
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while (p < n) {
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int k = snd_pcm_writei(m_pcm,
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m_bytebuf.data() + p * framesize, n - p);
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if (k < 0) {
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m_error = "write failed (";
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m_error += strerror(errno);
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m_error += ")";
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// After an underrun, ALSA keeps returning error codes until we
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// explicitly fix the stream.
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snd_pcm_recover(m_pcm, k, 0);
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return false;
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} else {
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p += k;
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}
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}
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return true;
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}
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/* end */
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