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  1. /*
  2.  * ADX ADPCM codecs
  3.  * Copyright (c) 2001,2003 BERO
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "libavutil/intreadwrite.h"
  23. #include "avcodec.h"
  24. #include "adx.h"
  25. #include "get_bits.h"
  26. #include "internal.h"
  27.  
  28. /**
  29.  * @file
  30.  * SEGA CRI adx codecs.
  31.  *
  32.  * Reference documents:
  33.  * http://ku-www.ss.titech.ac.jp/~yatsushi/adx.html
  34.  * adx2wav & wav2adx http://www.geocities.co.jp/Playtown/2004/
  35.  */
  36.  
  37. static av_cold int adx_decode_init(AVCodecContext *avctx)
  38. {
  39.     ADXContext *c = avctx->priv_data;
  40.     int ret, header_size;
  41.  
  42.     if (avctx->extradata_size >= 24) {
  43.         if ((ret = avpriv_adx_decode_header(avctx, avctx->extradata,
  44.                                             avctx->extradata_size, &header_size,
  45.                                             c->coeff)) < 0) {
  46.             av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
  47.             return AVERROR_INVALIDDATA;
  48.         }
  49.         c->channels      = avctx->channels;
  50.         c->header_parsed = 1;
  51.     }
  52.  
  53.     avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
  54.  
  55.     return 0;
  56. }
  57.  
  58. /**
  59.  * Decode 32 samples from 18 bytes.
  60.  *
  61.  * A 16-bit scalar value is applied to 32 residuals, which then have a
  62.  * 2nd-order LPC filter applied to it to form the output signal for a single
  63.  * channel.
  64.  */
  65. static int adx_decode(ADXContext *c, int16_t *out, int offset,
  66.                       const uint8_t *in, int ch)
  67. {
  68.     ADXChannelState *prev = &c->prev[ch];
  69.     GetBitContext gb;
  70.     int scale = AV_RB16(in);
  71.     int i;
  72.     int s0, s1, s2, d;
  73.  
  74.     /* check if this is an EOF packet */
  75.     if (scale & 0x8000)
  76.         return -1;
  77.  
  78.     init_get_bits(&gb, in + 2, (BLOCK_SIZE - 2) * 8);
  79.     out += offset;
  80.     s1 = prev->s1;
  81.     s2 = prev->s2;
  82.     for (i = 0; i < BLOCK_SAMPLES; i++) {
  83.         d  = get_sbits(&gb, 4);
  84.         s0 = ((d << COEFF_BITS) * scale + c->coeff[0] * s1 + c->coeff[1] * s2) >> COEFF_BITS;
  85.         s2 = s1;
  86.         s1 = av_clip_int16(s0);
  87.         *out++ = s1;
  88.     }
  89.     prev->s1 = s1;
  90.     prev->s2 = s2;
  91.  
  92.     return 0;
  93. }
  94.  
  95. static int adx_decode_frame(AVCodecContext *avctx, void *data,
  96.                             int *got_frame_ptr, AVPacket *avpkt)
  97. {
  98.     AVFrame *frame      = data;
  99.     int buf_size        = avpkt->size;
  100.     ADXContext *c       = avctx->priv_data;
  101.     int16_t **samples;
  102.     int samples_offset;
  103.     const uint8_t *buf  = avpkt->data;
  104.     const uint8_t *buf_end = buf + avpkt->size;
  105.     int num_blocks, ch, ret;
  106.  
  107.     if (c->eof) {
  108.         *got_frame_ptr = 0;
  109.         return buf_size;
  110.     }
  111.  
  112.     if (!c->header_parsed && buf_size >= 2 && AV_RB16(buf) == 0x8000) {
  113.         int header_size;
  114.         if ((ret = avpriv_adx_decode_header(avctx, buf, buf_size, &header_size,
  115.                                             c->coeff)) < 0) {
  116.             av_log(avctx, AV_LOG_ERROR, "error parsing ADX header\n");
  117.             return AVERROR_INVALIDDATA;
  118.         }
  119.         c->channels      = avctx->channels;
  120.         c->header_parsed = 1;
  121.         if (buf_size < header_size)
  122.             return AVERROR_INVALIDDATA;
  123.         buf      += header_size;
  124.         buf_size -= header_size;
  125.     }
  126.     if (!c->header_parsed)
  127.         return AVERROR_INVALIDDATA;
  128.  
  129.     /* calculate number of blocks in the packet */
  130.     num_blocks = buf_size / (BLOCK_SIZE * c->channels);
  131.  
  132.     /* if the packet is not an even multiple of BLOCK_SIZE, check for an EOF
  133.        packet */
  134.     if (!num_blocks || buf_size % (BLOCK_SIZE * avctx->channels)) {
  135.         if (buf_size >= 4 && (AV_RB16(buf) & 0x8000)) {
  136.             c->eof = 1;
  137.             *got_frame_ptr = 0;
  138.             return avpkt->size;
  139.         }
  140.         return AVERROR_INVALIDDATA;
  141.     }
  142.  
  143.     /* get output buffer */
  144.     frame->nb_samples = num_blocks * BLOCK_SAMPLES;
  145.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  146.         return ret;
  147.     samples = (int16_t **)frame->extended_data;
  148.     samples_offset = 0;
  149.  
  150.     while (num_blocks--) {
  151.         for (ch = 0; ch < c->channels; ch++) {
  152.             if (buf_end - buf < BLOCK_SIZE || adx_decode(c, samples[ch], samples_offset, buf, ch)) {
  153.                 c->eof = 1;
  154.                 buf = avpkt->data + avpkt->size;
  155.                 break;
  156.             }
  157.             buf_size -= BLOCK_SIZE;
  158.             buf      += BLOCK_SIZE;
  159.         }
  160.         samples_offset += BLOCK_SAMPLES;
  161.     }
  162.  
  163.     *got_frame_ptr = 1;
  164.  
  165.     return buf - avpkt->data;
  166. }
  167.  
  168. static void adx_decode_flush(AVCodecContext *avctx)
  169. {
  170.     ADXContext *c = avctx->priv_data;
  171.     memset(c->prev, 0, sizeof(c->prev));
  172.     c->eof = 0;
  173. }
  174.  
  175. AVCodec ff_adpcm_adx_decoder = {
  176.     .name           = "adpcm_adx",
  177.     .long_name      = NULL_IF_CONFIG_SMALL("SEGA CRI ADX ADPCM"),
  178.     .type           = AVMEDIA_TYPE_AUDIO,
  179.     .id             = AV_CODEC_ID_ADPCM_ADX,
  180.     .priv_data_size = sizeof(ADXContext),
  181.     .init           = adx_decode_init,
  182.     .decode         = adx_decode_frame,
  183.     .flush          = adx_decode_flush,
  184.     .capabilities   = CODEC_CAP_DR1,
  185.     .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
  186.                                                       AV_SAMPLE_FMT_NONE },
  187. };
  188.