audio_alsa_source.h

这是用python语言写的一个数字广播的信号处理工具包。利用它

/* -*- c++ -*- */
/*
 * Copyright 2004,2006 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 * 
 * GNU Radio is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#ifndef INCLUDED_AUDIO_ALSA_SOURCE_H
#define INCLUDED_AUDIO_ALSA_SOURCE_H

// use new ALSA API
#define ALSA_PCM_NEW_HW_PARAMS_API
#define ALSA_PCM_NEW_SW_PARAMS_API

#include <gr_sync_block.h>
#include <string>
#include <alsa/asoundlib.h>
#include <stdexcept>

class audio_alsa_source;
typedef boost::shared_ptr<audio_alsa_source> audio_alsa_source_sptr;

/*!
 * \brief Make an ALSA audio source.
 *
 * \param sampling_rate	sampling rate
 * \param dev ALSA pcm device name, e.g., "hw:0,0"
 * \param ok_to_block  (currently ignored)
 */
audio_alsa_source_sptr
audio_alsa_make_source (int sampling_rate,
			const std::string dev = "",
			bool ok_to_block = true);

/*!
 * \brief audio source using ALSA
 *
 * The source has between 1 and N input streams of floats, where N is
 * depends on the hardware characteristics of the selected device.
 *
 * Output samples will be in the range [-1,1].
 */
class audio_alsa_source : public gr_sync_block {
  friend audio_alsa_source_sptr
  audio_alsa_make_source (int sampling_rate,
			  const std::string device_name,
			  bool ok_to_block);

  // typedef for pointer to class work method
  typedef int (audio_alsa_source::*work_t)(int noutput_items,
					   gr_vector_const_void_star &input_items,
					   gr_vector_void_star &output_items);

  unsigned int		d_sampling_rate;
  std::string		d_device_name;
  snd_pcm_t            *d_pcm_handle;
  snd_pcm_hw_params_t  *d_hw_params;
  snd_pcm_sw_params_t  *d_sw_params;
  snd_pcm_format_t	d_format;
  unsigned int		d_nperiods;
  unsigned int		d_period_time_us;	// microseconds
  snd_pcm_uframes_t	d_period_size;		// in frames
  unsigned int		d_buffer_size_bytes;	// sizeof of d_buffer
  char		       *d_buffer;
  work_t	        d_worker;		// the work method to use
  unsigned int		d_hw_nchan;		// # of configured h/w channels
  bool			d_special_case_stereo_to_mono;

  // random stats
  int			d_noverruns;		// count of overruns
  int			d_nsuspends;		// count of suspends

  void output_error_msg (const char *msg, int err);
  void bail (const char *msg, int err) throw (std::runtime_error);

 protected:
  audio_alsa_source (int sampling_rate, const std::string device_name,
		     bool ok_to_block);

 public:
  ~audio_alsa_source ();
  
  bool check_topology (int ninputs, int noutputs);

  int work (int noutput_items,
	    gr_vector_const_void_star &input_items,
	    gr_vector_void_star &output_items);

protected:
  bool read_buffer (void *buffer, unsigned nframes, unsigned sizeof_frame);

  int work_s16 (int noutput_items,
		gr_vector_const_void_star &input_items,
		gr_vector_void_star &output_items);

  int work_s16_2x1 (int noutput_items,
		    gr_vector_const_void_star &input_items,
		    gr_vector_void_star &output_items);

  int work_s32 (int noutput_items,
		gr_vector_const_void_star &input_items,
		gr_vector_void_star &output_items);

  int work_s32_2x1 (int noutput_items,
		    gr_vector_const_void_star &input_items,
		    gr_vector_void_star &output_items);
};

#endif /* INCLUDED_AUDIO_ALSA_SOURCE_H */