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  1. /*
  2.  * Real Audio 1.0 (14.4K)
  3.  *
  4.  * Copyright (c) 2008 Vitor Sessak
  5.  * Copyright (c) 2003 Nick Kurshev
  6.  *     Based on public domain decoder at http://www.honeypot.net/audio
  7.  *
  8.  * This file is part of FFmpeg.
  9.  *
  10.  * FFmpeg is free software; you can redistribute it and/or
  11.  * modify it under the terms of the GNU Lesser General Public
  12.  * License as published by the Free Software Foundation; either
  13.  * version 2.1 of the License, or (at your option) any later version.
  14.  *
  15.  * FFmpeg is distributed in the hope that it will be useful,
  16.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18.  * Lesser General Public License for more details.
  19.  *
  20.  * You should have received a copy of the GNU Lesser General Public
  21.  * License along with FFmpeg; if not, write to the Free Software
  22.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23.  */
  24.  
  25. #include "libavutil/channel_layout.h"
  26. #include "avcodec.h"
  27. #include "get_bits.h"
  28. #include "internal.h"
  29. #include "ra144.h"
  30.  
  31.  
  32. static av_cold int ra144_decode_init(AVCodecContext * avctx)
  33. {
  34.     RA144Context *ractx = avctx->priv_data;
  35.  
  36.     ractx->avctx = avctx;
  37.  
  38.     ractx->lpc_coef[0] = ractx->lpc_tables[0];
  39.     ractx->lpc_coef[1] = ractx->lpc_tables[1];
  40.  
  41.     avctx->channels       = 1;
  42.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  43.     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
  44.  
  45.     return 0;
  46. }
  47.  
  48. static void do_output_subblock(RA144Context *ractx, const int16_t  *lpc_coefs,
  49.                                int gval, GetBitContext *gb)
  50. {
  51.     int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
  52.     int gain    = get_bits(gb, 8);
  53.     int cb1_idx = get_bits(gb, 7);
  54.     int cb2_idx = get_bits(gb, 7);
  55.  
  56.     ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, gval,
  57.                           gain);
  58. }
  59.  
  60. /** Uncompress one block (20 bytes -> 160*2 bytes). */
  61. static int ra144_decode_frame(AVCodecContext * avctx, void *data,
  62.                               int *got_frame_ptr, AVPacket *avpkt)
  63. {
  64.     AVFrame *frame     = data;
  65.     const uint8_t *buf = avpkt->data;
  66.     int buf_size = avpkt->size;
  67.     static const uint8_t sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
  68.     unsigned int refl_rms[NBLOCKS];           // RMS of the reflection coefficients
  69.     int16_t block_coefs[NBLOCKS][LPC_ORDER];  // LPC coefficients of each sub-block
  70.     unsigned int lpc_refl[LPC_ORDER];         // LPC reflection coefficients of the frame
  71.     int i, j;
  72.     int ret;
  73.     int16_t *samples;
  74.     unsigned int energy;
  75.  
  76.     RA144Context *ractx = avctx->priv_data;
  77.     GetBitContext gb;
  78.  
  79.     if (buf_size < FRAME_SIZE) {
  80.         av_log(avctx, AV_LOG_ERROR,
  81.                "Frame too small (%d bytes). Truncated file?\n", buf_size);
  82.         *got_frame_ptr = 0;
  83.         return AVERROR_INVALIDDATA;
  84.     }
  85.  
  86.     /* get output buffer */
  87.     frame->nb_samples = NBLOCKS * BLOCKSIZE;
  88.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  89.         return ret;
  90.     samples = (int16_t *)frame->data[0];
  91.  
  92.     init_get_bits8(&gb, buf, FRAME_SIZE);
  93.  
  94.     for (i = 0; i < LPC_ORDER; i++)
  95.         lpc_refl[i] = ff_lpc_refl_cb[i][get_bits(&gb, sizes[i])];
  96.  
  97.     ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);
  98.     ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);
  99.  
  100.     energy = ff_energy_tab[get_bits(&gb, 5)];
  101.  
  102.     refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
  103.     refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,
  104.                             energy <= ractx->old_energy,
  105.                             ff_t_sqrt(energy*ractx->old_energy) >> 12);
  106.     refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);
  107.     refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);
  108.  
  109.     ff_int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
  110.  
  111.     for (i=0; i < NBLOCKS; i++) {
  112.         do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
  113.  
  114.         for (j=0; j < BLOCKSIZE; j++)
  115.             *samples++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
  116.     }
  117.  
  118.     ractx->old_energy = energy;
  119.     ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
  120.  
  121.     FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
  122.  
  123.     *got_frame_ptr = 1;
  124.  
  125.     return FRAME_SIZE;
  126. }
  127.  
  128. AVCodec ff_ra_144_decoder = {
  129.     .name           = "real_144",
  130.     .long_name      = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
  131.     .type           = AVMEDIA_TYPE_AUDIO,
  132.     .id             = AV_CODEC_ID_RA_144,
  133.     .priv_data_size = sizeof(RA144Context),
  134.     .init           = ra144_decode_init,
  135.     .decode         = ra144_decode_frame,
  136.     .capabilities   = CODEC_CAP_DR1,
  137. };
  138.