mpv/libmpcodecs/ad_imaadpcm.c

/*
 * IMA ADPCM decoder
 *
 * This file is in charge of decoding all of the various IMA ADPCM data
 * formats that various entities have created. Details about the data
 * formats can be found here:
 *   http://www.pcisys.net/~melanson/codecs/
 *
 * So far, this file handles these formats:
 *   'ima4': IMA ADPCM found in QT files
 *     0x11: IMA ADPCM found in MS AVI/ASF/WAV files
 *     0x61: DK4 ADPCM found in certain AVI files on Sega Saturn CD-ROMs;
 *           note that this is a 'rogue' format number in that it was
 *           never officially registered with Microsoft
 * 0x1100736d: IMA ADPCM coded like in MS AVI/ASF/WAV found in QT files
 *
 * Copyright (c) 2002 Mike Melanson
 *
 * This file is part of MPlayer.
 *
 * MPlayer 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.
 *
 * MPlayer 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 MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <inttypes.h>

#include <libavutil/intreadwrite.h>

#include "config.h"
#include "mpbswap.h"
#include "ad_internal.h"

#define MS_IMA_ADPCM_PREAMBLE_SIZE 4

#define QT_IMA_ADPCM_PREAMBLE_SIZE 2
#define QT_IMA_ADPCM_BLOCK_SIZE 0x22
#define QT_IMA_ADPCM_SAMPLES_PER_BLOCK 64

// pertinent tables for IMA ADPCM
static const int16_t adpcm_step[89] =
{
  7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
  19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
  50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
  130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
  337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
  876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
  2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
  5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
  15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
};

static const int8_t adpcm_index[8] =
{
  -1, -1, -1, -1, 2, 4, 6, 8,
};

// useful macros
// clamp a number between 0 and 88
#define CLAMP_0_TO_88(x) x = av_clip(x, 0, 88);
// clamp a number within a signed 16-bit range
#define CLAMP_S16(x) x = av_clip_int16(x);
// clamp a number above 16
#define CLAMP_ABOVE_16(x)  if (x < 16) x = 16;

static const ad_info_t info =
{
	"IMA ADPCM audio decoder",
	"imaadpcm",
	"Nick Kurshev",
	"Mike Melanson",
	""
};

LIBAD_EXTERN(imaadpcm)

static int preinit(sh_audio_t *sh_audio)
{
  // not exactly sure what this field is for
  sh_audio->audio_out_minsize = 8192;

  // if format is "ima4", assume the audio is coming from a QT file which
  // indicates constant block size, whereas an AVI/ASF/WAV file will fill
  // in this field with 0x11
  if ((sh_audio->format == 0x11) || (sh_audio->format == 0x61) ||
      (sh_audio->format == 0x1100736d))
  {
    sh_audio->ds->ss_div = (sh_audio->wf->nBlockAlign -
      (MS_IMA_ADPCM_PREAMBLE_SIZE * sh_audio->wf->nChannels)) * 2;
    sh_audio->ds->ss_mul = sh_audio->wf->nBlockAlign;
  }
  else
  {
    sh_audio->ds->ss_div = QT_IMA_ADPCM_SAMPLES_PER_BLOCK;
    sh_audio->ds->ss_mul = QT_IMA_ADPCM_BLOCK_SIZE * sh_audio->wf->nChannels;
  }
  sh_audio->audio_in_minsize=sh_audio->ds->ss_mul;
  return 1;
}

static int init(sh_audio_t *sh_audio)
{
  /* IMA-ADPCM 4:1 audio codec:*/
  sh_audio->channels=sh_audio->wf->nChannels;
  sh_audio->samplerate=sh_audio->wf->nSamplesPerSec;
  /* decodes 34 byte -> 64 short*/
  sh_audio->i_bps =
    (sh_audio->ds->ss_mul * sh_audio->samplerate) / sh_audio->ds->ss_div;
  sh_audio->samplesize=2;

  return 1;
}

static void uninit(sh_audio_t *sh_audio)
{
}

static int control(sh_audio_t *sh_audio,int cmd,void* arg, ...)
{
  if(cmd==ADCTRL_SKIP_FRAME){
    demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,sh_audio->ds->ss_mul);
    return CONTROL_TRUE;
  }
  return CONTROL_UNKNOWN;
}

static void decode_nibbles(unsigned short *output,
  int output_size, int channels,
  int predictor[2], int index[2])
{
  int step[2];
  int i;
  int sign;
  int delta;
  int channel_number = 0;

  step[0] = adpcm_step[index[0]];
  step[1] = adpcm_step[index[1]];

  for (i = 0; i < output_size; i++)
  {
    delta = output[i];
    sign = delta & 8;
    delta = delta & 7;

    index[channel_number] += adpcm_index[delta];
    CLAMP_0_TO_88(index[channel_number]);

    delta = 2 * delta + 1;
    if (sign) delta = -delta;

    predictor[channel_number] += (delta * step[channel_number]) >> 3;

    CLAMP_S16(predictor[channel_number]);
    output[i] = predictor[channel_number];
    step[channel_number] = adpcm_step[index[channel_number]];

    // toggle channel
    channel_number ^= channels - 1;

  }
}

static int qt_ima_adpcm_decode_block(unsigned short *output,
  unsigned char *input, int channels, int block_size)
{
  int initial_predictor[2] = {0};
  int initial_index[2] = {0};
  int i;

  if (channels != 1) channels = 2;
  if (block_size < channels * QT_IMA_ADPCM_BLOCK_SIZE)
    return -1;

  for (i = 0; i < channels; i++) {
    initial_index[i] = initial_predictor[i] = (int16_t)AV_RB16(&input[i * QT_IMA_ADPCM_BLOCK_SIZE]);

    // mask, sign-extend, and clamp the predictor portion
    initial_predictor[i] &= ~0x7F;
    CLAMP_S16(initial_predictor[i]);

    // mask and clamp the index portion
    initial_index[i] &= 0x7F;
    CLAMP_0_TO_88(initial_index[i]);
  }

  // break apart all of the nibbles in the block
  if (channels == 1)
    for (i = 0; i < QT_IMA_ADPCM_SAMPLES_PER_BLOCK / 2; i++)
    {
      output[i * 2 + 0] = input[2 + i] & 0x0F;
      output[i * 2 + 1] = input[2 + i] >> 4;
    }
  else
    for (i = 0; i < QT_IMA_ADPCM_SAMPLES_PER_BLOCK / 2; i++)
    {
      output[i * 4 + 0] = input[2 + i] & 0x0F;
      output[i * 4 + 1] = input[2 + QT_IMA_ADPCM_BLOCK_SIZE + i] & 0x0F;
      output[i * 4 + 2] = input[2 + i] >> 4;
      output[i * 4 + 3] = input[2 + QT_IMA_ADPCM_BLOCK_SIZE + i] >> 4;
    }

  decode_nibbles(output,
    QT_IMA_ADPCM_SAMPLES_PER_BLOCK * channels, channels,
    initial_predictor, initial_index);

  return QT_IMA_ADPCM_SAMPLES_PER_BLOCK * channels;
}

static int ms_ima_adpcm_decode_block(unsigned short *output,
  unsigned char *input, int channels, int block_size)
{
  int predictor[2];
  int index[2];
  int i;
  int channel_counter;
  int channel_index;
  int channel_index_l;
  int channel_index_r;

  if (channels != 1) channels = 2;
  if (block_size < MS_IMA_ADPCM_PREAMBLE_SIZE * channels)
    return -1;

  for (i = 0; i < channels; i++) {
    predictor[i] = (int16_t)AV_RL16(&input[i * 4]);
    index[i] = input[i * 4 + 2];
  }

  if (channels == 1)
    for (i = 0;
      i < (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels); i++)
    {
      output[i * 2 + 0] = input[MS_IMA_ADPCM_PREAMBLE_SIZE + i] & 0x0F;
      output[i * 2 + 1] = input[MS_IMA_ADPCM_PREAMBLE_SIZE + i] >> 4;
    }
  else
  {
    // encoded as 8 nibbles (4 bytes) per channel; switch channel every
    // 4th byte
    channel_counter = 0;
    channel_index_l = 0;
    channel_index_r = 1;
    channel_index = channel_index_l;
    for (i = 0;
      i < (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels); i++)
    {
      output[channel_index + 0] =
        input[MS_IMA_ADPCM_PREAMBLE_SIZE * 2 + i] & 0x0F;
      output[channel_index + 2] =
        input[MS_IMA_ADPCM_PREAMBLE_SIZE * 2 + i] >> 4;
      channel_index += 4;
      channel_counter++;
      if (channel_counter == 4)
      {
        channel_index_l = channel_index;
        channel_index = channel_index_r;
      }
      else if (channel_counter == 8)
      {
        channel_index_r = channel_index;
        channel_index = channel_index_l;
        channel_counter = 0;
      }
    }
  }

  decode_nibbles(output,
    (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels) * 2,
    channels,
    predictor, index);

  return (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels) * 2;
}

static int dk4_ima_adpcm_decode_block(unsigned short *output,
  unsigned char *input, int channels, int block_size)
{
  int i;
  int output_ptr;
  int predictor[2];
  int index[2];

  if (channels != 1) channels = 2;
  if (block_size < MS_IMA_ADPCM_PREAMBLE_SIZE * channels)
    return -1;

  for (i = 0; i < channels; i++) {
    // the first predictor value goes straight to the output
    predictor[i] = output[i] = (int16_t)AV_RL16(&input[i * 4]);
    index[i] = input[i * 4 + 2];
  }

  output_ptr = channels;
  for (i = MS_IMA_ADPCM_PREAMBLE_SIZE * channels; i < block_size; i++)
  {
    output[output_ptr++] = input[i] >> 4;
    output[output_ptr++] = input[i] & 0x0F;
  }

  decode_nibbles(&output[channels],
    (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels) * 2 - channels,
    channels,
    predictor, index);

  return (block_size - MS_IMA_ADPCM_PREAMBLE_SIZE * channels) * 2 - channels;
}

static int decode_audio(sh_audio_t *sh_audio,unsigned char *buf,int minlen,int maxlen)
{
  int res = -1;
  int (*decode_func)(unsigned short *output, unsigned char *input, int channels, int block_size) = qt_ima_adpcm_decode_block;
  if (demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,
    sh_audio->ds->ss_mul) !=
    sh_audio->ds->ss_mul)
    return -1;

  if ((sh_audio->format == 0x11) || (sh_audio->format == 0x1100736d))
    decode_func = ms_ima_adpcm_decode_block;
  else if (sh_audio->format == 0x61)
    decode_func = dk4_ima_adpcm_decode_block;

  res = decode_func((unsigned short*)buf, sh_audio->a_in_buffer,
                    sh_audio->wf->nChannels, sh_audio->ds->ss_mul);
  return res < 0 ? res : 2 * res;
}