path: root/src/libxineadec/logpcm.c

/*
 * Copyright (C) 2000-2002 the xine project
 *
 * This file is part of xine, a free video player.
 *
 * xine 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.
 *
 * xine 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
 *
 * Logarithmic PCM Decoder
 * This audio decoder handles the mu-law and A-law logarithmic coding
 * standards.
 *
 * mu-law -> PCM conversion routine found at this site:
 *   http://www.speech.cs.cmu.edu/comp.speech/Section2/Q2.7.html
 * and credited to this person:
 *   Craig Reese: IDA/Supercomputing Research Center
 *
 * A-law -> PCM conversion routine lifted from SoX Sound eXchange:
 *   http://sox.sourceforge.net/
 * which listed the code as being lifted from Sun Microsystems.
 *
 * $Id: logpcm.c,v 1.12 2003/01/08 01:02:31 miguelfreitas Exp $
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>
#include <string.h>

#include "buffer.h"
#include "xine_internal.h"
#include "video_out.h"
#include "audio_out.h"
#include "xineutils.h"
#include "bswap.h"

#define AUDIOBUFSIZE 128*1024
#define LOGPCM_BITS_PER_SAMPLE 16

typedef struct {
  audio_decoder_class_t   decoder_class;
} logpcm_class_t;

typedef struct logpcm_decoder_s {
  audio_decoder_t   audio_decoder;

  xine_stream_t    *stream;

  int64_t           pts;

  int               output_open;
  int               output_channels;
  int               samplerate;

  unsigned char    *buf;
  int               bufsize;
  int               size;

  short             logtable[256];
} logpcm_decoder_t;

/*
** This routine converts from ulaw to 16 bit linear.
**
** Craig Reese: IDA/Supercomputing Research Center
** 29 September 1989
**
** References:
** 1) CCITT Recommendation G.711  (very difficult to follow)
** 2) MIL-STD-188-113,"Interoperability and Performance Standards
**     for Analog-to_Digital Conversion Techniques,"
**     17 February 1987
**
** Input: 8 bit ulaw sample
** Output: signed 16 bit linear sample
*/

static int mulaw2linear(unsigned char mulawbyte) {

  static int exp_lut[8] = {0,132,396,924,1980,4092,8316,16764};
  int sign, exponent, mantissa, sample;

  mulawbyte = ~mulawbyte;
  sign = (mulawbyte & 0x80);
  exponent = (mulawbyte >> 4) & 0x07;
  mantissa = mulawbyte & 0x0F;
  sample = exp_lut[exponent] + (mantissa << (exponent + 3));
  if (sign != 0) sample = -sample;

  return(sample);
}

/*
 * The following A-law -> PCM conversion function came from SoX which in
 * turn came from Sun Microsystems.
 */
#define SIGN_BIT        (0x80)          /* Sign bit for a A-law byte. */
#define QUANT_MASK      (0xf)           /* Quantization field mask. */
#define SEG_SHIFT       (4)             /* Left shift for segment number. */
#define SEG_MASK        (0x70)          /* Segment field mask. */

/*
 * alaw2linear() - Convert an A-law value to 16-bit signed linear PCM
 *
 */
static int alaw2linear(unsigned char a_val) {

  int t;
  int seg;

  a_val ^= 0x55;

  t = (a_val & QUANT_MASK) << 4;
  seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
  switch (seg) {
  case 0:
    t += 8;
    break;

  case 1:
    t += 0x108;
    break;

  default:
    t += 0x108;
    t <<= seg - 1;
  }
  return ((a_val & SIGN_BIT) ? t : -t);
}


static void logpcm_decode_data (audio_decoder_t *this_gen, buf_element_t *buf) {

  logpcm_decoder_t *this = (logpcm_decoder_t *) this_gen;
  audio_buffer_t *audio_buffer;
  int in;
  int i;
  int bytes_to_send;

  if (buf->decoder_flags & BUF_FLAG_HEADER) {

    this->samplerate = buf->decoder_info[1];
    this->output_channels = buf->decoder_info[3];
    this->buf = xine_xmalloc(AUDIOBUFSIZE);
    this->bufsize = AUDIOBUFSIZE;
    this->size = 0;

    /* stream/meta info */
    this->stream->meta_info[XINE_META_INFO_AUDIOCODEC] = 
      (buf->type == BUF_AUDIO_MULAW) ? strdup("mu-law log PCM") :
      strdup("A-law log PCM");

    /* pre-calculate the possible log values */
    if (buf->type == BUF_AUDIO_MULAW)
      for (i = 0; i < 256; i++)
        this->logtable[i] = (short)mulaw2linear(i);
    else if (buf->type == BUF_AUDIO_ALAW)
      for (i = 0; i < 256; i++)
        this->logtable[i] = (short)alaw2linear(i);

    return;
  }

  if (!this->output_open) {
    this->output_open = this->stream->audio_out->open(this->stream->audio_out,
      this->stream, LOGPCM_BITS_PER_SAMPLE, this->samplerate,
      (this->output_channels == 2) ? AO_CAP_MODE_STEREO : AO_CAP_MODE_MONO);
  }

  /* if the audio still isn't open, bail */
  if (!this->output_open)
    return;

  if( this->size + buf->size > this->bufsize ) {
    this->bufsize = this->size + 2 * buf->size;
    printf("logpcm: increasing source buffer to %d to avoid overflow.\n",
      this->bufsize);
    this->buf = realloc( this->buf, this->bufsize );
  }

  xine_fast_memcpy (&this->buf[this->size], buf->content, buf->size);
  this->size += buf->size;

  if (buf->decoder_flags & BUF_FLAG_FRAME_END)  { /* time to decode a frame */

    /* iterate through each 8-bit sample in the input buffer */
    in = 0;
    while (in < this->size) {

      audio_buffer = this->stream->audio_out->get_buffer (this->stream->audio_out);
      if (audio_buffer->mem_size == 0) {
        printf ("logpcm: Help! Allocated audio buffer with nothing in it!\n");
        return;
      }

      /* this->size and in are sample counts, mem_size is a byte count */
      if ((this->size - in) > (audio_buffer->mem_size / 2))
        bytes_to_send = audio_buffer->mem_size / 2;
      else
        bytes_to_send = this->size - in;

      /* fill up this buffer */
      for (i = 0; i < bytes_to_send; i++)
        audio_buffer->mem[i] = this->logtable[this->buf[in++]];

      audio_buffer->num_frames = bytes_to_send / this->output_channels;
      audio_buffer->vpts = buf->pts;
      buf->pts = 0;  /* only first buffer gets the real pts */
      this->stream->audio_out->put_buffer (this->stream->audio_out, audio_buffer, this->stream);
    }

    /* reset internal accumulation buffer */
    this->size = 0;
  }
}

static void logpcm_reset (audio_decoder_t *this_gen) {
}

static void logpcm_discontinuity (audio_decoder_t *this_gen) {
  logpcm_decoder_t *this = (logpcm_decoder_t *) this_gen;

  this->pts = 0;
}

static void logpcm_dispose (audio_decoder_t *this_gen) {

  logpcm_decoder_t *this = (logpcm_decoder_t *) this_gen;

  if (this->output_open)
    this->stream->audio_out->close (this->stream->audio_out, this->stream);
  this->output_open = 0;

  if (this->buf)
    free(this->buf);

  free (this_gen);
}

static audio_decoder_t *open_plugin (audio_decoder_class_t *class_gen, xine_stream_t *stream) {

  logpcm_decoder_t *this ;

  this = (logpcm_decoder_t *) malloc (sizeof (logpcm_decoder_t));

  this->audio_decoder.decode_data         = logpcm_decode_data;
  this->audio_decoder.reset               = logpcm_reset;
  this->audio_decoder.discontinuity       = logpcm_discontinuity;
  this->audio_decoder.dispose             = logpcm_dispose;

  this->output_open = 0;
  this->output_channels = 0;
  this->stream = stream;
  this->buf = NULL;
  this->size = 0;

  return &this->audio_decoder;
}

static char *get_identifier (audio_decoder_class_t *this) {
  return "Log PCM";
}

static char *get_description (audio_decoder_class_t *this) {
  return "Logarithmic PCM audio format decoder plugin";
}

static void dispose_class (audio_decoder_class_t *this) {
  free (this);
}

static void *init_plugin (xine_t *xine, void *data) {

  logpcm_class_t *this ;

  this = (logpcm_class_t *) malloc (sizeof (logpcm_class_t));

  this->decoder_class.open_plugin     = open_plugin;
  this->decoder_class.get_identifier  = get_identifier;
  this->decoder_class.get_description = get_description;
  this->decoder_class.dispose         = dispose_class;

  return this;
}

static uint32_t audio_types[] = { BUF_AUDIO_MULAW, BUF_AUDIO_ALAW, 0 };

static decoder_info_t dec_info_audio = {
  audio_types,         /* supported types */
  9                    /* priority        */
};

plugin_info_t xine_plugin_info[] = {
  /* type, API, "name", version, special_info, init_function */  
  { PLUGIN_AUDIO_DECODER, 13, "logpcm", XINE_VERSION_CODE, &dec_info_audio, &init_plugin },
  { PLUGIN_NONE, 0, "", 0, NULL, NULL }
};