/*
  * Copyright (c) CMU 1993 Computer Science, Speech Group
  *                        Chengxiang Lu and Alex Hauptmann
  * Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
  * Copyright (c) 2009 Kenan Gillet
  * Copyright (c) 2010 Martin Storsjo
  *

  * 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
  */
 
 /**
  * @file
  * G.722 ADPCM audio decoder
  *
  * This G.722 decoder is a bit-exact implementation of the ITU G.722
  * specification for all three specified bitrates - 64000bps, 56000bps
  * and 48000bps. It passes the ITU tests.
  *
  * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
  *       respectively of each byte are ignored.
  */
 

 #include "libavutil/channel_layout.h"
 #include "libavutil/opt.h"

 #include "avcodec.h"
 #include "get_bits.h"
 #include "g722.h"

 #include "internal.h"

 
 #define OFFSET(x) offsetof(G722Context, x)
 #define AD AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {

     { "bits_per_codeword", "Bits per G722 codeword", OFFSET(bits_per_codeword), AV_OPT_TYPE_INT, { .i64 = 8 }, 6, 8, AD },

     { NULL }
 };
 
 static const AVClass g722_decoder_class = {
     .class_name = "g722 decoder",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };

 
 static av_cold int g722_decode_init(AVCodecContext * avctx)
 {
     G722Context *c = avctx->priv_data;
 

     avctx->channels       = 1;
     avctx->channel_layout = AV_CH_LAYOUT_MONO;
     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;

 
     c->band[0].scale_factor = 8;
     c->band[1].scale_factor = 2;
     c->prev_samples_pos = 22;
 

     ff_g722dsp_init(&c->dsp);
 

     return 0;
 }
 
 static const int16_t low_inv_quant5[32] = {
      -35,   -35, -2919, -2195, -1765, -1458, -1219, -1023,
     -858,  -714,  -587,  -473,  -370,  -276,  -190,  -110,
     2919,  2195,  1765,  1458,  1219,  1023,   858,   714,
      587,   473,   370,   276,   190,   110,    35,   -35
 };
 

 static const int16_t * const low_inv_quants[3] = { ff_g722_low_inv_quant6,

                                                            low_inv_quant5,
                                                    ff_g722_low_inv_quant4 };

 
 static int g722_decode_frame(AVCodecContext *avctx, void *data,

                              int *got_frame_ptr, AVPacket *avpkt)

 {
     G722Context *c = avctx->priv_data;

     AVFrame *frame = data;

     int16_t *out_buf;
     int j, ret;

     const int skip = 8 - c->bits_per_codeword;

     const int16_t *quantizer_table = low_inv_quants[skip];
     GetBitContext gb;
 

     /* get output buffer */

     frame->nb_samples = avpkt->size * 2;

     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

         return ret;

     out_buf = (int16_t *)frame->data[0];

     init_get_bits(&gb, avpkt->data, avpkt->size * 8);
 
     for (j = 0; j < avpkt->size; j++) {

         int ilow, ihigh, rlow, rhigh, dhigh;

         int xout[2];

 
         ihigh = get_bits(&gb, 2);
         ilow = get_bits(&gb, 6 - skip);
         skip_bits(&gb, skip);
 

         rlow = av_clip_intp2((c->band[0].scale_factor * quantizer_table[ilow] >> 10)
                       + c->band[0].s_predictor, 14);

 
         ff_g722_update_low_predictor(&c->band[0], ilow >> (2 - skip));
 

         dhigh = c->band[1].scale_factor * ff_g722_high_inv_quant[ihigh] >> 10;

         rhigh = av_clip_intp2(dhigh + c->band[1].s_predictor, 14);

 
         ff_g722_update_high_predictor(&c->band[1], dhigh, ihigh);
 
         c->prev_samples[c->prev_samples_pos++] = rlow + rhigh;
         c->prev_samples[c->prev_samples_pos++] = rlow - rhigh;

         c->dsp.apply_qmf(c->prev_samples + c->prev_samples_pos - 24, xout);
         *out_buf++ = av_clip_int16(xout[0] >> 11);
         *out_buf++ = av_clip_int16(xout[1] >> 11);

         if (c->prev_samples_pos >= PREV_SAMPLES_BUF_SIZE) {
             memmove(c->prev_samples, c->prev_samples + c->prev_samples_pos - 22,
                     22 * sizeof(c->prev_samples[0]));
             c->prev_samples_pos = 22;
         }

     }

     *got_frame_ptr = 1;

     return avpkt->size;
 }
 
 AVCodec ff_adpcm_g722_decoder = {
     .name           = "g722",

     .long_name      = NULL_IF_CONFIG_SMALL("G.722 ADPCM"),

     .type           = AVMEDIA_TYPE_AUDIO,

     .id             = AV_CODEC_ID_ADPCM_G722,

     .priv_data_size = sizeof(G722Context),
     .init           = g722_decode_init,
     .decode         = g722_decode_frame,

     .capabilities   = AV_CODEC_CAP_DR1,

     .priv_class     = &g722_decoder_class,

 };