mpeg2audio.cc

ac3的解码程序

/*
   File: mpeg2audio.cc

   By: Alex Theo de Jong
   Created: Febraury 1996

   Description:
   MPEG 2 Audio class. The MPEG 2 Audio decoder reads from the
   stream buffer, decodes and plays the audio on the SUN Solaris 
   or SGI Irix audio device.
*/

#define RELEASE "1.2, November 1996"

#ifdef __GNUG__
#pragma implementation
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iomanip.h>
#include <fstream.h>
#include <sys/errno.h>
#include <unistd.h>
#ifdef IRIX
#include <dmedia/audio.h>
#endif
#ifdef SOLARIS
#include <sys/audioio.h>
#endif
#ifdef LINUX
#include <sys/soundcard.h>
#endif

#include "athread.hh"

#include "error.hh"
#include "debug.hh"
#include "util.hh"

#include "sync.hh"
#include "mpeg2const.hh"
#include "mpeg2buff.hh"

#include "mpeg2audio.hh"

extern int decode_ac3(AudioStream *,Synchronization *);

/*
 *
 * Mpeg2Audio
 *
 */

Mpeg2Audio::Mpeg2Audio(Mpeg2Buffer* input_buffer, Synchronization* s, int audio, int c, char** v) :
  verbose_mode(True),
  filter_check(False),
  stdout_mode(False),
  which_channels(both),
  use_speaker(False),
  use_headphone(False),
  use_line_out(False),
  use_own_scalefactor(False),
  argc(c),
  terminate(0), terminated(0)
{
  sync=s;

  if (input_buffer) 
    stream=new AudioStream(input_buffer, sync);
  else stream=0;

  if (argc) argv=v;
  else argv=0;

  header=new Header;
  buffer=0;
  filter1=0;
  filter2=0;


  if (audio == 1) {
#ifdef DEBUG
    Mpeg2Audio::player(this);
#else
    if (athr_create((void*(*)(void*))Mpeg2Audio::player, this, &thread_id)<0){
      error("could not create audio player");
      athr_exit(0);
    }
#endif
  }
  else {
#ifdef DEBUG
    Mpeg2Audio::ac3_player(this);
#else
    if (athr_create((void*(*)(void*))Mpeg2Audio::ac3_player, this, &thread_id)<0){
      error("could not create audio player");
      athr_exit(0);
    }
#endif
  }

  sched_param param;
  int policy;
  if (athr_getschedparam(thread_id, &policy, &param)<0){
    error("could not get thread priority");
  }
#ifdef LINUX
  param.sched_priority+=2;
//  policy = SCHED_RR;
  TRACER("AUDIOPRIORITY=" << param.sched_priority << "(" << param.sched_priority-2 << ")");
#else
  param.prio+=2;
  TRACER("AUDIOPRIORITY=" << param.prio << "(" << param.prio-2 << ")");
#endif
  if (athr_setschedparam(thread_id, policy, &param)<0){
    error("could not set thread priority");
  }
}


Mpeg2Audio::~Mpeg2Audio(){
  TRACER("Mpeg2Audio::~Mpeg2Audio()");
//  terminate=1;
  if (!terminated){
    TRACER("waiting for audio thread ...");
    athr_join(thread_id);
    // In order to play TS stream without audio it shouln't wait here
    // This is a bug that needs to be fixed somewhere else.
    // Just a temporary fix.  Alex 05/27/96
  }
  TRACER("audio thread done\nDeleting audio stuff ... ");
  delete stream;
  delete header;
  delete buffer;
  delete filter1;
  delete filter2;
  TRACER("audio thread done");
}


void* Mpeg2Audio::player(Mpeg2Audio* base){
  base->terminated=0;
  base->terminate=0;

  if (base->options())
    base->play();

  base->terminated=1;
  TRACER("audio thread terminated");
  athr_exit(0);
  return 0;
}

void* Mpeg2Audio::ac3_player(Mpeg2Audio* base){
  base->terminated=0;
  base->terminate=0;

  decode_ac3(base->stream,base->sync);

  base->terminated=1;
  TRACER("audio thread terminated");
  athr_exit(0);
  return 0;
}

void Mpeg2Audio::usage(const char* name){
  msg("usage: "); msg(name); message(" <filename> [options]");
  message("options:");
  message("\t-q\tquiet");
  message("\t-l\tdecode only the left channel");
  message("\t-r\tdecode only the right channel");
  message("\t-ux\tsend audio signal to speaker(x:s), headphone (x:h), line out (x:l)");
  message("\t-c\tcheck for filter range violations");
  message("\t-fn\tuse this (n) scalefactor instead of the default value 32768");

  message("");
  message("\tMPEG 2 Audio Player\n");
  msg("\tversion "); message(RELEASE);
  message("\tAlex Theo de Jong (e-mail: [e-mail])\n");
  message("\tMulti-Media and Digital Video Group");
  message("\tNational Institute of Standards and Technology");
  message("\tGaithersburg, Md, U.S.A.\n\n");
  message("");
  message("Original code by:");
  message("\tTobias Bading");
  message("\tBerlin University of Technology, Germany");
}  


int Mpeg2Audio::options(){
  if (argc < 2 || argv[1][0]=='-'){
    usage(argv[0]);
    return 0;
  }

  filename=argv[1];

  for (int i=2; i < argc; i++){
    if (argv[i][0] == '-' && argv[i][1])
      switch (argv[i][1]){
      case 'q': verbose_mode = False; break;
	  case 's': stdout_mode = True;  break;
  	  case 'l': which_channels = left; break;
	  case 'r': which_channels = right; break;
	  case 'u':
	    switch (argv[i][2]){
	    case 's': use_speaker = True; break;
	    case 'h': use_headphone = True; break;
	    case 'l': use_line_out = True; break;
	  }
	  break;
  	  case 'c': filter_check = True; break;
	  case 'f':
        use_own_scalefactor = True;
        scalefactor=atoi(&argv[i][2]);
        break;
	  default: msg("unknown option "); msg(argv[i]); message(" - ignored");
    }

  }

  if (!(use_speaker || use_headphone || use_line_out)) use_speaker=True;

  return 1;
}


int Mpeg2Audio::play(){
  bool read_ready = False, write_ready = False;

  if (!stream) stream=new AudioStream(filename);	// read from file


  if (!header->read_header(stream, &crc)) {
    error("no header found!");
    athr_exit(0);
  }

  // get info from header of first frame:
  layer = header->layer ();
  if ((mode = header->mode ()) == single_channel)
    which_channels = left;
  sample_frequency = header->sample_frequency ();

  // create filter(s):
  if (use_own_scalefactor) filter1 = new SynthesisFilter(0, scalefactor);
  else                     filter1 = new SynthesisFilter(0);
  if (mode != single_channel && which_channels == both)
    if (use_own_scalefactor) filter2 = new SynthesisFilter(1, scalefactor);
    else                     filter2 = new SynthesisFilter(1);

  // create buffer:
  if (stdout_mode)
#ifdef IRIX
    buffer=0;
#else
    if (mode == single_channel || which_channels != both)
      buffer = new ShortObuffer(1);
    else
      buffer = new ShortObuffer (2);
#endif
  else

#ifdef IRIX
    if (mode == single_channel || which_channels != both)
         buffer = new IrixObuffer (1, header);
    else buffer = new IrixObuffer (2, header);
#else
#ifdef SOLARIS
    if (SparcObuffer::class_suitable()){
      if (mode == single_channel || which_channels != both)
        buffer = new SparcObuffer (1, header, use_speaker, use_headphone, use_line_out);
      else
        buffer = new SparcObuffer (2, header, use_speaker, use_headphone, use_line_out);
    }
    else {
      error("Sorry, no suitable audio device detected, please use stdout mode");
      athr_exit(0);
    }
#else
#ifdef LINUX
    if (LinuxObuffer::class_suitable()){
      if (mode == single_channel || which_channels != both)
        buffer = new LinuxObuffer (1, header);
      else
        buffer = new LinuxObuffer (2, header);
    }
    else {
      error("Sorry, no suitable audio device detected, please use stdout mode");
      athr_exit(0);
    }
#endif  // !LINUX
#endif	// !SOLARIS
#endif	// !IRIX

  if (!buffer){
    error("no audio device available");
    return 0;
  }

  if (verbose_mode){
    // print informations about the stream
    char *name = strrchr (filename, '/');
    if (name) ++name;
    else        name = filename;
    cerr << name << " is a layer " << header->layer_string () << ' '
	 << header->mode_string () << " MPEG audio stream with";
    if (!header->checksums ())
      cerr << "out";
    cerr << " checksums.\nThe sample frequency is "
	 << header->sample_frequency_string () << " at a bitrate of "
	 << header->bitrate_string () << ".\n"
	    "This stream is ";
    if (header->original ()) cerr << "an original";
    else                     cerr << "a copy";
    cerr << " and is ";
    if (!header->copyright ()) cerr << "not ";
    cerr << "copyright protected.\n";
  }

  do {
    // is there a change in important parameters?
    // (bitrate switching is allowed)
    if (header->layer () != layer){
      // layer switching is allowed
      if (verbose_mode)
        cerr << "switching to layer " << header->layer_string () << ".\n";
      layer = header->layer ();
    }
    if ((mode == single_channel && header->mode () != single_channel) ||
	(mode != single_channel && header->mode () == single_channel)){
      // switching from single channel to stereo or vice versa is not allowed
      error("illegal switch from single channel to stereo or vice versa!");
      athr_exit(0);
    }
    if (header->sample_frequency () != sample_frequency){
      // switching the sample frequency is not allowed
      error("sorry, can't switch the sample frequency in the middle of the stream!");
      athr_exit(0);
    }

    unsigned int i=0;
    // create subband objects:
    if (header->layer()==1){
      if (header->mode()==single_channel)
        for (i=0; i<header->number_of_subbands(); ++i)
          subbands[i]=new SubbandLayer1(i);
      else if (header->mode()==joint_stereo){
        for (i=0; i<header->intensity_stereo_bound(); ++i)
          subbands[i]=new SubbandLayer1Stereo(i);
        for (; i<header->number_of_subbands(); ++i)
          subbands[i]=new SubbandLayer1IntensityStereo(i);
      }
      else
        for (i=0; i<header->number_of_subbands(); ++i)
          subbands[i]=new SubbandLayer1Stereo(i);
    }
    else if (header->layer()==2){
      if (header->mode()==single_channel)
        for (i = 0; i<header->number_of_subbands (); ++i)
          subbands[i] = new SubbandLayer2 (i);
      else if (header->mode () == joint_stereo){
        for (i = 0; i < header->intensity_stereo_bound (); ++i)
          subbands[i] = new SubbandLayer2Stereo (i);
        for (; i < header->number_of_subbands (); ++i)
          subbands[i] = new SubbandLayer2IntensityStereo (i);
      }
      else
        for (i = 0; i < header->number_of_subbands (); ++i)
          subbands[i] = new SubbandLayer2Stereo (i);
    }
    else {
      error("sorry, layer 3 not implemented!");
      athr_exit(0);
    }
    
    // start to read audio data:
    for (i = 0; i < header->number_of_subbands(); ++i)
      subbands[i]->read_allocation (stream, header, crc);
    
    if (header->layer()==2)
      for (i = 0; i < header->number_of_subbands(); ++i)
        ((SubbandLayer2 *)subbands[i])->read_scalefactor_selection (stream, crc);
    
    if (!crc || header->checksum_ok()){
        // no checksums or checksum ok, continue reading from stream:
        for (i = 0; i < header->number_of_subbands (); ++i)
          subbands[i]->read_scalefactor (stream, header);
        
        do
          {
            for (i = 0; i < header->number_of_subbands (); ++i)
              read_ready = subbands[i]->read_sampledata (stream);
            
            do
              {
              for (i = 0; i < header->number_of_subbands (); ++i)
                write_ready = subbands[i]->put_next_sample (which_channels, filter1, filter2);
              
              filter1->calculate_pcm_samples (buffer);
              if (which_channels == both && header->mode () != single_channel)
                filter2->calculate_pcm_samples (buffer);
            }
            while (!write_ready);
          }
        while (!read_ready);
        
        if (sync) sync->wait(2); // wait for PTS, id=2, if <0, end of file

        buffer->write_buffer(1);		// write to stdout
      }
    else
      // Sh*t! Wrong crc checksum in frame!
      cerr << "WARNING: frame contains wrong crc checksum! (throwing frame away)\n";
    
    for (i=0; i < header->number_of_subbands (); ++i) delete subbands[i];
  }
  while (!terminate && header->read_header(stream, &crc) && (!sync || !sync->done(2)));
 
  uint32 range_violations = filter1->violations ();
  if (mode != single_channel && which_channels == both)
   range_violations += filter2->violations ();

  if (filter_check){
    // check whether (one of) the filter(s) produced values not in [-1.0, 1.0]:
    if (range_violations){
      cerr << range_violations << " range violations have occured!\n";
      if (stdout_mode)
        cerr << "If you notice these violations,\n";
      else
        cerr << "If you have noticed these violations,\n";
      cerr << "please use the -f option with the value ";
      if (mode != single_channel && which_channels == both &&
          filter2->hardest_violation () > filter1->hardest_violation ())
        cerr << filter2->recommended_scalefactor ();
      else
        cerr << filter1->recommended_scalefactor ();
      cerr << "\nor a greater value up to 32768 and try again.\n";
    }
  }
  if (verbose_mode){
    // print playtime of stream:
    real playtime = filter1->seconds_played (Header::frequency (sample_frequency));
    uint32 minutes = (uint32)(playtime / 60.0);
    uint32 seconds = (uint32)playtime - minutes * 60;
    uint32 centiseconds = (uint32)((playtime - (real)(minutes * 60) - (real)seconds) * 100.0);
    cerr << "end of stream, playtime: " << minutes << ':'
      << setw (2) << setfill ('0')
	 << seconds << '.'
	 << setw (2) << setfill ('0')
	 << centiseconds << '\n';
  }

  return 0;
}