text: ﻿/*
   * Real Audio 1.0 (14.4K)
   *
   * Copyright (c) 2008 Vitor Sessak
   * Copyright (c) 2003 Nick Kurshev
   *     Based on public domain decoder at http://www.honeypot.net/audio
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg 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
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "libavutil/intmath.h"
  #include "avcodec.h"
  #include "get_bits.h"
  #include "ra144.h"
  
  
  static av_cold int ra144_decode_init(AVCodecContext * avctx)
  {
      RA144Context *ractx = avctx->priv_data;
  
      ractx->avctx = avctx;
  
      ractx->lpc_coef[0] = ractx->lpc_tables[0];
      ractx->lpc_coef[1] = ractx->lpc_tables[1];
  
      avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  
      avcodec_get_frame_defaults(&ractx->frame);
      avctx->coded_frame = &ractx->frame;
  
      return 0;
  }
  
  static void do_output_subblock(RA144Context *ractx, const uint16_t  *lpc_coefs,
                                 int gval, GetBitContext *gb)
  {
      int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none
      int gain    = get_bits(gb, 8);
      int cb1_idx = get_bits(gb, 7);
      int cb2_idx = get_bits(gb, 7);
  
      ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, gval,
                            gain);
  }
  
  /** Uncompress one block (20 bytes -> 160*2 bytes). */
  static int ra144_decode_frame(AVCodecContext * avctx, void *data,
                                int *got_frame_ptr, AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      static const uint8_t sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
      unsigned int refl_rms[NBLOCKS];           // RMS of the reflection coefficients
      uint16_t block_coefs[NBLOCKS][LPC_ORDER]; // LPC coefficients of each sub-block
      unsigned int lpc_refl[LPC_ORDER];         // LPC reflection coefficients of the frame
      int i, j;
      int ret;
      int16_t *samples;
      unsigned int energy;
  
      RA144Context *ractx = avctx->priv_data;
      GetBitContext gb;
  
      /* get output buffer */
      ractx->frame.nb_samples = NBLOCKS * BLOCKSIZE;
      if ((ret = avctx->get_buffer(avctx, &ractx->frame)) < 0) {
          av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
          return ret;
      }
      samples = (int16_t *)ractx->frame.data[0];
  
      if(buf_size < FRAMESIZE) {
          av_log(avctx, AV_LOG_ERROR,
                 "Frame too small (%d bytes). Truncated file?\n", buf_size);
          *got_frame_ptr = 0;
          return buf_size;
      }
      init_get_bits(&gb, buf, FRAMESIZE * 8);
  
      for (i = 0; i < LPC_ORDER; i++)
          lpc_refl[i] = ff_lpc_refl_cb[i][get_bits(&gb, sizes[i])];
  
      ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);
      ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);
  
      energy = ff_energy_tab[get_bits(&gb, 5)];
  
      refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
      refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,
                              energy <= ractx->old_energy,
                              ff_t_sqrt(energy*ractx->old_energy) >> 12);
      refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);
      refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);
  
      ff_int_to_int16(block_coefs[3], ractx->lpc_coef[0]);
  
      for (i=0; i < NBLOCKS; i++) {
          do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);
  
          for (j=0; j < BLOCKSIZE; j++)
              *samples++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);
      }
  
      ractx->old_energy = energy;
      ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
  
      FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
  
      *got_frame_ptr   = 1;
      *(AVFrame *)data = ractx->frame;
  
      return FRAMESIZE;
  }
  
  AVCodec ff_ra_144_decoder = {
      .name           = "real_144",
      .type           = AVMEDIA_TYPE_AUDIO,
      .id             = CODEC_ID_RA_144,
      .priv_data_size = sizeof(RA144Context),
      .init           = ra144_decode_init,
      .decode         = ra144_decode_frame,
      .capabilities   = CODEC_CAP_DR1,
      .long_name      = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),
  };
  