/*
  * SMPTE 302M decoder
  * Copyright (c) 2008 Laurent Aimar <fenrir@videolan.org>
  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
  *

  * 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/intreadwrite.h"

 #include "libavutil/log.h"

 #include "avcodec.h"

 #include "internal.h"

 #include "mathops.h"

 
 #define AES3_HEADER_LEN 4
 

 typedef struct S302MDecodeContext {
     AVFrame frame;
 } S302MDecodeContext;
 

 static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
                                     int buf_size)
 {
     uint32_t h;

     int frame_size, channels, bits;

 
     if (buf_size <= AES3_HEADER_LEN) {
         av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
         return AVERROR_INVALIDDATA;
     }
 
     /*
      * AES3 header :
      * size:            16
      * number channels   2
      * channel_id        8
      * bits per samples  2
      * alignments        4
      */
 
     h = AV_RB32(buf);
     frame_size =  (h >> 16) & 0xffff;
     channels   = ((h >> 14) & 0x0003) * 2 +  2;
     bits       = ((h >>  4) & 0x0003) * 4 + 16;
 
     if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
         av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
         return AVERROR_INVALIDDATA;
     }
 
     /* Set output properties */
     avctx->bits_per_coded_sample = bits;
     if (bits > 16)

         avctx->sample_fmt = AV_SAMPLE_FMT_S32;

     else

         avctx->sample_fmt = AV_SAMPLE_FMT_S16;

 
     avctx->channels    = channels;

     switch(channels) {
         case 2:
             avctx->channel_layout = AV_CH_LAYOUT_STEREO;
             break;
         case 4:
             avctx->channel_layout = AV_CH_LAYOUT_QUAD;
             break;

         case 6:
             avctx->channel_layout = AV_CH_LAYOUT_5POINT1_BACK;
             break;

         case 8:
             avctx->channel_layout = AV_CH_LAYOUT_5POINT1_BACK | AV_CH_LAYOUT_STEREO_DOWNMIX;
     }

     avctx->sample_rate = 48000;
     avctx->bit_rate    = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
                          32 * (48000 / (buf_size * 8 /
                                         (avctx->channels *
                                          (avctx->bits_per_coded_sample + 4))));
 
     return frame_size;
 }
 
 static int s302m_decode_frame(AVCodecContext *avctx, void *data,

                               int *got_frame_ptr, AVPacket *avpkt)

 {

     S302MDecodeContext *s = avctx->priv_data;

     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;

     int block_size, ret;

 
     int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
     if (frame_size < 0)
         return frame_size;
 
     buf_size -= AES3_HEADER_LEN;
     buf      += AES3_HEADER_LEN;
 

     /* get output buffer */
     block_size = (avctx->bits_per_coded_sample + 4) / 4;
     s->frame.nb_samples = 2 * (buf_size / block_size) / avctx->channels;

     if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {

         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
         return ret;
     }
 
     buf_size = (s->frame.nb_samples * avctx->channels / 2) * block_size;

 
     if (avctx->bits_per_coded_sample == 24) {

         uint32_t *o = (uint32_t *)s->frame.data[0];

         for (; buf_size > 6; buf_size -= 7) {

             *o++ = (ff_reverse[buf[2]]        << 24) |
                    (ff_reverse[buf[1]]        << 16) |
                    (ff_reverse[buf[0]]        <<  8);
             *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
                    (ff_reverse[buf[5]]        << 20) |
                    (ff_reverse[buf[4]]        << 12) |
                    (ff_reverse[buf[3] & 0x0f] <<  4);

             buf += 7;
         }
     } else if (avctx->bits_per_coded_sample == 20) {

         uint32_t *o = (uint32_t *)s->frame.data[0];

         for (; buf_size > 5; buf_size -= 6) {

             *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
                    (ff_reverse[buf[1]]        << 20) |
                    (ff_reverse[buf[0]]        << 12);
             *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
                    (ff_reverse[buf[4]]        << 20) |
                    (ff_reverse[buf[3]]        << 12);

             buf += 6;
         }
     } else {

         uint16_t *o = (uint16_t *)s->frame.data[0];

         for (; buf_size > 4; buf_size -= 5) {

             *o++ = (ff_reverse[buf[1]]        <<  8) |
                     ff_reverse[buf[0]];
             *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
                    (ff_reverse[buf[3]]        <<  4) |
                    (ff_reverse[buf[2]]        >>  4);

             buf += 5;
         }
     }
 

     *got_frame_ptr   = 1;
     *(AVFrame *)data = s->frame;
 
     return avpkt->size;
 }
 
 static int s302m_decode_init(AVCodecContext *avctx)
 {
     S302MDecodeContext *s = avctx->priv_data;
 
     avcodec_get_frame_defaults(&s->frame);
     avctx->coded_frame = &s->frame;
 
     return 0;

 }
 
 
 AVCodec ff_s302m_decoder = {
     .name           = "s302m",
     .type           = AVMEDIA_TYPE_AUDIO,

     .id             = AV_CODEC_ID_S302M,

     .priv_data_size = sizeof(S302MDecodeContext),
     .init           = s302m_decode_init,

     .decode         = s302m_decode_frame,

     .capabilities   = CODEC_CAP_DR1,

     .long_name      = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
 };