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  1. /*
  2.  * SMPTE 302M decoder
  3.  * Copyright (c) 2008 Laurent Aimar <fenrir@videolan.org>
  4.  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. #include "libavutil/intreadwrite.h"
  24. #include "libavutil/log.h"
  25. #include "avcodec.h"
  26. #include "internal.h"
  27. #include "mathops.h"
  28.  
  29. #define AES3_HEADER_LEN 4
  30.  
  31. static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
  32.                                     int buf_size)
  33. {
  34.     uint32_t h;
  35.     int frame_size, channels, bits;
  36.  
  37.     if (buf_size <= AES3_HEADER_LEN) {
  38.         av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
  39.         return AVERROR_INVALIDDATA;
  40.     }
  41.  
  42.     /*
  43.      * AES3 header :
  44.      * size:            16
  45.      * number channels   2
  46.      * channel_id        8
  47.      * bits per samples  2
  48.      * alignments        4
  49.      */
  50.  
  51.     h = AV_RB32(buf);
  52.     frame_size =  (h >> 16) & 0xffff;
  53.     channels   = ((h >> 14) & 0x0003) * 2 +  2;
  54.     bits       = ((h >>  4) & 0x0003) * 4 + 16;
  55.  
  56.     if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
  57.         av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
  58.         return AVERROR_INVALIDDATA;
  59.     }
  60.  
  61.     /* Set output properties */
  62.     avctx->bits_per_raw_sample = bits;
  63.     if (bits > 16)
  64.         avctx->sample_fmt = AV_SAMPLE_FMT_S32;
  65.     else
  66.         avctx->sample_fmt = AV_SAMPLE_FMT_S16;
  67.  
  68.     avctx->channels    = channels;
  69.     switch(channels) {
  70.         case 2:
  71.             avctx->channel_layout = AV_CH_LAYOUT_STEREO;
  72.             break;
  73.         case 4:
  74.             avctx->channel_layout = AV_CH_LAYOUT_QUAD;
  75.             break;
  76.         case 6:
  77.             avctx->channel_layout = AV_CH_LAYOUT_5POINT1_BACK;
  78.             break;
  79.         case 8:
  80.             avctx->channel_layout = AV_CH_LAYOUT_5POINT1_BACK | AV_CH_LAYOUT_STEREO_DOWNMIX;
  81.     }
  82.     avctx->sample_rate = 48000;
  83.     avctx->bit_rate    = 48000 * avctx->channels * (avctx->bits_per_raw_sample + 4) +
  84.                          32 * (48000 / (buf_size * 8 /
  85.                                         (avctx->channels *
  86.                                          (avctx->bits_per_raw_sample + 4))));
  87.  
  88.     return frame_size;
  89. }
  90.  
  91. static int s302m_decode_frame(AVCodecContext *avctx, void *data,
  92.                               int *got_frame_ptr, AVPacket *avpkt)
  93. {
  94.     AVFrame *frame     = data;
  95.     const uint8_t *buf = avpkt->data;
  96.     int buf_size       = avpkt->size;
  97.     int block_size, ret;
  98.  
  99.     int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
  100.     if (frame_size < 0)
  101.         return frame_size;
  102.  
  103.     buf_size -= AES3_HEADER_LEN;
  104.     buf      += AES3_HEADER_LEN;
  105.  
  106.     /* get output buffer */
  107.     block_size = (avctx->bits_per_raw_sample + 4) / 4;
  108.     frame->nb_samples = 2 * (buf_size / block_size) / avctx->channels;
  109.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  110.         return ret;
  111.  
  112.     buf_size = (frame->nb_samples * avctx->channels / 2) * block_size;
  113.  
  114.     if (avctx->bits_per_raw_sample == 24) {
  115.         uint32_t *o = (uint32_t *)frame->data[0];
  116.         for (; buf_size > 6; buf_size -= 7) {
  117.             *o++ = (ff_reverse[buf[2]]        << 24) |
  118.                    (ff_reverse[buf[1]]        << 16) |
  119.                    (ff_reverse[buf[0]]        <<  8);
  120.             *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
  121.                    (ff_reverse[buf[5]]        << 20) |
  122.                    (ff_reverse[buf[4]]        << 12) |
  123.                    (ff_reverse[buf[3] & 0x0f] <<  4);
  124.             buf += 7;
  125.         }
  126.     } else if (avctx->bits_per_raw_sample == 20) {
  127.         uint32_t *o = (uint32_t *)frame->data[0];
  128.         for (; buf_size > 5; buf_size -= 6) {
  129.             *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
  130.                    (ff_reverse[buf[1]]        << 20) |
  131.                    (ff_reverse[buf[0]]        << 12);
  132.             *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
  133.                    (ff_reverse[buf[4]]        << 20) |
  134.                    (ff_reverse[buf[3]]        << 12);
  135.             buf += 6;
  136.         }
  137.     } else {
  138.         uint16_t *o = (uint16_t *)frame->data[0];
  139.         for (; buf_size > 4; buf_size -= 5) {
  140.             *o++ = (ff_reverse[buf[1]]        <<  8) |
  141.                     ff_reverse[buf[0]];
  142.             *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
  143.                    (ff_reverse[buf[3]]        <<  4) |
  144.                    (ff_reverse[buf[2]]        >>  4);
  145.             buf += 5;
  146.         }
  147.     }
  148.  
  149.     *got_frame_ptr = 1;
  150.  
  151.     return avpkt->size;
  152. }
  153.  
  154. AVCodec ff_s302m_decoder = {
  155.     .name           = "s302m",
  156.     .long_name      = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
  157.     .type           = AVMEDIA_TYPE_AUDIO,
  158.     .id             = AV_CODEC_ID_S302M,
  159.     .decode         = s302m_decode_frame,
  160.     .capabilities   = CODEC_CAP_DR1,
  161. };
  162.