SDR-DAB_Qt-DAB/sources/backend/audio/faad-decoder.cpp

#
/*
 *    Copyright (C) 2013 .. 2024
 *    Jan van Katwijk (J.vanKatwijk@gmail.com)
 *    Lazy Chair Computing
 *
 *    This file is part of Qt-DAB
 *
 *    Qt-DAB 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 2 of the License, or
 *    (at your option) any later version.
 *
 *    Qt-DAB 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 Qt-DAB; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include        "faad-decoder.h"
#include        "neaacdec.h"
#include        "radio.h"

	faadDecoder::faadDecoder        (RadioInterface *mr,
	                                 RingBuffer<complex16> *buffer) {
	this    -> audioBuffer  = buffer;
	aacCap          = NeAACDecGetCapabilities();
	aacHandle       = NeAACDecOpen();
	aacConf         = NeAACDecGetCurrentConfiguration (aacHandle);
	aacInitialized  = false;
	baudRate        = 48000;
	connect (this, &faadDecoder::newAudio,
	         mr, &RadioInterface::newAudio);
}

	faadDecoder::~faadDecoder	() {
	NeAACDecClose   (aacHandle);
}

int get_aac_channel_configuration (int16_t m_mpeg_surround_config,
	                           uint8_t aacChannelMode) {

	switch(m_mpeg_surround_config) {
	   case 0:     // no surround
	      return aacChannelMode ? 2 : 1;
	   case 1:     // 5.1
	      return 6;
	   case 2:     // 7.1
	      return 7;
	   default:
	      return -1;
	}
}

bool    faadDecoder::initialize (stream_parms	*sp) {
long unsigned int sample_rate;
uint8_t channels;
/* AudioSpecificConfig structure (the only way to select 960 transform here!)
 *
 *  00010 = AudioObjectType 2 (AAC LC)
 *  xxxx  = (core) sample rate index
 *  xxxx  = (core) channel config
 *  100   = GASpecificConfig with 960 transform
 *
 * SBR: implicit signaling sufficient - libfaad2
 * automatically assumes SBR on sample rates <= 24 kHz
 * => explicit signaling works, too, but is not necessary here
 *
 * PS:  implicit signaling sufficient - libfaad2
 * therefore always uses stereo output (if PS support was enabled)
 * => explicit signaling not possible, as libfaad2 does not
 * support AudioObjectType 29 (PS)
 */

	int core_sr_index =
	       sp -> dacRate ? (sp -> sbrFlag ? 6 : 3) :
	                       (sp -> sbrFlag ? 8 : 5);   // 24/48/16/32 kHz
	int core_ch_config =
	           get_aac_channel_configuration (sp -> mpegSurround,
	                                          sp ->aacChannelMode);
	if (core_ch_config == -1) {
	   printf ("Unrecognized mpeg surround config (ignored): %d\n",
	                                       sp -> mpegSurround);
	   return false;
	}

	uint8_t asc[2];
	asc [0] = 0b00010 << 3 | core_sr_index >> 1;
	asc [1] = (core_sr_index & 0x01) << 7 | core_ch_config << 3 | 0b100;
	long int init_result = NeAACDecInit2 (aacHandle,
	                                      asc,
	                                      sizeof (asc),
	                                      &sample_rate,
	                                      &channels);
	if (init_result != 0) {
/*      If some error initializing occured, skip the file */
	   printf ("Error initializing decoder library: %s\n",
	                         NeAACDecGetErrorMessage (-init_result));
	   NeAACDecClose (aacHandle);
	   return false;
	}
	return true;
}

int16_t faadDecoder::MP42PCM (stream_parms *sp,
	                      uint8_t	buffer [],
	                      int16_t   bufferLength) {
int16_t samples;
long unsigned int       sampleRate;
int16_t *outBuffer;
NeAACDecFrameInfo       hInfo;
uint8_t channels;

	if (!aacInitialized) {
	   if (!initialize (sp))
	      return 0;
	   aacInitialized = true;
	}

	outBuffer = (int16_t *)NeAACDecDecode (aacHandle,
	                                       &hInfo, buffer, bufferLength);
	sampleRate      = hInfo. samplerate;

	samples         = hInfo. samples;
	if ((sampleRate == 24000) ||
	    (sampleRate == 32000) ||
	    (sampleRate == 48000) ||
	    (sampleRate !=  (long unsigned)baudRate))
	      baudRate = sampleRate;


	channels        = hInfo. channels;
	if (hInfo. error != 0) {
	   fprintf (stderr, "Warning: %s\n",
	               faacDecGetErrorMessage (hInfo. error));
	   return -1;
	}

	if (channels == 2) {
	   for (int i = 0; i < samples / 2; i ++) {
	      complex16 s = complex16 (outBuffer [2 * i],
	                               outBuffer [2 * i + 1]);
	      audioBuffer -> putDataIntoBuffer (&s, 1);
	   }
	   if (audioBuffer -> GetRingBufferReadAvailable() > (int)sampleRate / 10)
	      newAudio (sampleRate / 10, sampleRate, hInfo. ps, hInfo. sbr);

	}
	else
	if (channels == 1) {
	   for (int i = 0; i < samples; i ++) {
	      complex16 s = complex16 (outBuffer [i], outBuffer [i]);
	      audioBuffer  -> putDataIntoBuffer (&s, 1);
	   }
	   if (audioBuffer -> GetRingBufferReadAvailable() > (int)sampleRate / 8)
	      newAudio (sampleRate / 10, sampleRate, hInfo. ps, hInfo. sbr);

	}
	else
	   fprintf (stderr, "Cannot handle these channels\n");

	return channels; 
}