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126 lines
4.1 KiB
C++
126 lines
4.1 KiB
C++
/* ---------------------------------------------------------------------------
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** This software is in the public domain, furnished "as is", without technical
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** support, and with no warranty, express or implied, as to its usefulness for
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** any purpose.
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**
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** ALSACapture.cpp
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**
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** V4L2 RTSP streamer
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**
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** ALSA capture overide of V4l2Capture
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**
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** -------------------------------------------------------------------------*/
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#ifndef ALSA_CAPTURE
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#define ALSA_CAPTURE
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#include <alsa/asoundlib.h>
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struct ALSACaptureParameters
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{
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ALSACaptureParameters(const char* devname, unsigned int sampleRate, unsigned int channels, int verbose) :
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m_devName(devname), m_sampleRate(sampleRate), m_channels(channels), m_verbose(verbose) {};
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std::string m_devName;
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unsigned int m_sampleRate;
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unsigned int m_channels;
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int m_verbose;
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};
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class ALSACapture
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{
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public:
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static ALSACapture* createNew(const ALSACaptureParameters & params) { return new ALSACapture(params); }
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virtual ~ALSACapture()
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{
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if (m_pcm != NULL)
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{
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snd_pcm_close (m_pcm);
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}
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}
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protected:
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ALSACapture(const ALSACaptureParameters & params) : m_pcm(NULL), m_bufferSize(0), m_periodSize(0)
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{
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snd_pcm_hw_params_t *hw_params = NULL;
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unsigned int rate = params.m_sampleRate;
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int err = 0;
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// open PCM device
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if ((err = snd_pcm_open (&m_pcm, params.m_devName.c_str(), SND_PCM_STREAM_CAPTURE, 0)) < 0) {
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fprintf (stderr, "cannot open audio device %s (%s)\n", params.m_devName.c_str(), snd_strerror (err));
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}
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// configure hw_params
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else if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
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fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params_any (m_pcm, hw_params)) < 0) {
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fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params_set_access (m_pcm, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
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fprintf (stderr, "cannot set access type (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params_set_format (m_pcm, hw_params, SND_PCM_FORMAT_S16_BE)) < 0) {
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fprintf (stderr, "cannot set sample format (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params_set_rate_near (m_pcm, hw_params, &rate, 0)) < 0) {
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fprintf (stderr, "cannot set sample rate (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params_set_channels (m_pcm, hw_params, params.m_channels)) < 0) {
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fprintf (stderr, "cannot set channel count (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_hw_params (m_pcm, hw_params)) < 0) {
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fprintf (stderr, "cannot set parameters (%s)\n", snd_strerror (err));
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}
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// get buffer size
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else if ((err = snd_pcm_get_params(m_pcm, &m_bufferSize, &m_periodSize)) < 0) {
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fprintf (stderr, "cannot get parameters (%s)\n", snd_strerror (err));
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}
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// start capture
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else if ((err = snd_pcm_prepare (m_pcm)) < 0) {
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fprintf (stderr, "cannot prepare audio interface for use (%s)\n", snd_strerror (err));
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}
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else if ((err = snd_pcm_start (m_pcm)) < 0) {
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fprintf (stderr, "cannot start audio interface for use (%s)\n", snd_strerror (err));
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}
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}
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public:
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virtual size_t read(char* buffer, size_t bufferSize)
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{
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return snd_pcm_readi (m_pcm, buffer, m_periodSize);
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}
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virtual int getFd()
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{
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unsigned int nbfs = 1;
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struct pollfd pfds[nbfs];
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pfds[0].fd = -1;
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if (m_pcm != 0)
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{
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int count = snd_pcm_poll_descriptors_count (m_pcm);
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int err = snd_pcm_poll_descriptors(m_pcm, pfds, count);
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if (err < 0) {
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fprintf (stderr, "cannot snd_pcm_poll_descriptors (%s)\n", snd_strerror (err));
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}
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}
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return pfds[0].fd;
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}
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unsigned long getBufferSize() { return m_bufferSize; };
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private:
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snd_pcm_t* m_pcm;
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unsigned long m_bufferSize;
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unsigned long m_periodSize;
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};
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#endif
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