libavcodec/g722dec.c

   1 /*
   2  * Copyright (c) CMU 1993 Computer Science, Speech Group
   3  *                        Chengxiang Lu and Alex Hauptmann
   4  * Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
   5  * Copyright (c) 2009 Kenan Gillet
   6  * Copyright (c) 2010 Martin Storsjo
   7  *
   8  * This file is part of Libav.
   9  *
  10  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23  */
  24
  25 /**
  26  * @file
  27  * G.722 ADPCM audio decoder
  28  *
  29  * This G.722 decoder is a bit-exact implementation of the ITU G.722
  30  * specification for all three specified bitrates - 64000bps, 56000bps
  31  * and 48000bps. It passes the ITU tests.
  32  *
  33  * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
  34  *       respectively of each byte are ignored.
  35  */
  36
  37 #include "libavutil/channel_layout.h"
  38 #include "libavutil/opt.h"
  39
  40 #include "avcodec.h"
  41 #include "bitstream.h"
  42 #include "g722.h"
  43 #include "internal.h"
  44
  45 #define OFFSET(x) offsetof(G722Context, x)
  46 #define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
  47 static const AVOption options[] = {
  48     { "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_INT, { .i64 = 8 }, 6, 8, AD },
  49     { NULL }
  50 };
  51
  52 static const AVClass g722_decoder_class = {
  53     .class_name = "g722 decoder",
  54     .item_name  = av_default_item_name,
  55     .option     = options,
  56     .version    = LIBAVUTIL_VERSION_INT,
  57 };
  58
  59 static av_cold int g722_decode_init(AVCodecContext * avctx)
  60 {
  61     G722Context *c = avctx->priv_data;
  62
  63     avctx->channels       = 1;
  64     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  65     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
  66
  67     c->band[0].scale_factor = 8;
  68     c->band[1].scale_factor = 2;
  69     c->prev_samples_pos = 22;
  70
  71     ff_g722dsp_init(&c->dsp);
  72
  73     return 0;
  74 }
  75
  76 static const int16_t low_inv_quant5[32] = {
  77      -35,   -35, -2919, -2195, -1765, -1458, -1219, -1023,
  78     -858,  -714,  -587,  -473,  -370,  -276,  -190,  -110,
  79     2919,  2195,  1765,  1458,  1219,  1023,   858,   714,
  80      587,   473,   370,   276,   190,   110,    35,   -35
  81 };
  82
  83 static const int16_t * const low_inv_quants[3] = { ff_g722_low_inv_quant6,
  84                                                            low_inv_quant5,
  85                                                    ff_g722_low_inv_quant4 };
  86
  87 static int g722_decode_frame(AVCodecContext *avctx, void *data,
  88                              int *got_frame_ptr, AVPacket *avpkt)
  89 {
  90     G722Context *c = avctx->priv_data;
  91     AVFrame *frame = data;
  92     int16_t *out_buf;
  93     int j, ret;
  94     const int skip = 8 - c->bits_per_codeword;
  95     const int16_t *quantizer_table = low_inv_quants[skip];
  96     BitstreamContext bc;
  97
  98     /* get output buffer */
  99     frame->nb_samples = avpkt->size * 2;
 100     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
 101         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
 102         return ret;
 103     }
 104     out_buf = (int16_t *)frame->data[0];
 105
 106     bitstream_init8(&bc, avpkt->data, avpkt->size);
 107
 108     for (j = 0; j < avpkt->size; j++) {
 109         int ilow, ihigh, rlow, rhigh, dhigh;
 110         int xout[2];
 111
 112         ihigh = bitstream_read(&bc, 2);
 113         ilow  = bitstream_read(&bc, 6 - skip);
 114         bitstream_skip(&bc, skip);
 115
 116         rlow = av_clip_intp2((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
 117                       + c->band[0].s_predictor, 14);
 118
 119         ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
 120
 121         dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;
 122         rhigh = av_clip_intp2(dhigh + c->band[1].s_predictor, 14);
 123
 124         ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
 125
 126         c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
 127         c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;
 128         c->dsp.apply_qmf(c->prev_samples + c->prev_samples_pos - 24, xout);
 129         *out_buf++ = av_clip_int16(xout[0] >> 11);
 130         *out_buf++ = av_clip_int16(xout[1] >> 11);
 131         if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
 132             memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
 133                     22 * sizeof(c->prev_samples[0]));
 134             c->prev_samples_pos = 22;
 135         }
 136     }
 137
 138     *got_frame_ptr = 1;
 139
 140     return avpkt->size;
 141 }
 142
 143 AVCodec ff_adpcm_g722_decoder = {
 144     .name           = "g722",
 145     .long_name      = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),
 146     .type           = AVMEDIA_TYPE_AUDIO,
 147     .id             = AV_CODEC_ID_ADPCM_G722,
 148     .priv_data_size = sizeof(G722Context),
 149     .init           = g722_decode_init,
 150     .decode         = g722_decode_frame,
 151     .capabilities   = AV_CODEC_CAP_DR1,
 152     .priv_class     = &g722_decoder_class,
 153 };