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  1. /*
  2.  * Aura 2 decoder
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. /**
  22.  * @file
  23.  * Aura 2 decoder
  24.  */
  25.  
  26. #include "avcodec.h"
  27. #include "internal.h"
  28. #include "libavutil/internal.h"
  29.  
  30. static av_cold int aura_decode_init(AVCodecContext *avctx)
  31. {
  32.     /* width needs to be divisible by 4 for this codec to work */
  33.     if (avctx->width & 0x3)
  34.         return AVERROR(EINVAL);
  35.     avctx->pix_fmt = AV_PIX_FMT_YUV422P;
  36.  
  37.     return 0;
  38. }
  39.  
  40. static int aura_decode_frame(AVCodecContext *avctx,
  41.                              void *data, int *got_frame,
  42.                              AVPacket *pkt)
  43. {
  44.     AVFrame *frame = data;
  45.     uint8_t *Y, *U, *V;
  46.     uint8_t val;
  47.     int x, y, ret;
  48.     const uint8_t *buf = pkt->data;
  49.  
  50.     /* prediction error tables (make it clear that they are signed values) */
  51.     const int8_t *delta_table = (const int8_t*)buf + 16;
  52.  
  53.     if (pkt->size != 48 + avctx->height * avctx->width) {
  54.         av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
  55.                pkt->size, 48 + avctx->height * avctx->width);
  56.         return AVERROR_INVALIDDATA;
  57.     }
  58.  
  59.     /* pixel data starts 48 bytes in, after 3x16-byte tables */
  60.     buf += 48;
  61.  
  62.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  63.         return ret;
  64.  
  65.     Y = frame->data[0];
  66.     U = frame->data[1];
  67.     V = frame->data[2];
  68.  
  69.     /* iterate through each line in the height */
  70.     for (y = 0; y < avctx->height; y++) {
  71.         /* reset predictors */
  72.         val  = *buf++;
  73.         U[0] = val & 0xF0;
  74.         Y[0] = val << 4;
  75.         val  = *buf++;
  76.         V[0] = val & 0xF0;
  77.         Y[1] = Y[0] + delta_table[val & 0xF];
  78.         Y   += 2; U++; V++;
  79.  
  80.         /* iterate through the remaining pixel groups (4 pixels/group) */
  81.         for (x = 1; x < (avctx->width >> 1); x++) {
  82.             val  = *buf++;
  83.             U[0] = U[-1] + delta_table[val >> 4];
  84.             Y[0] = Y[-1] + delta_table[val & 0xF];
  85.             val  = *buf++;
  86.             V[0] = V[-1] + delta_table[val >> 4];
  87.             Y[1] = Y[ 0] + delta_table[val & 0xF];
  88.             Y   += 2; U++; V++;
  89.         }
  90.         Y += frame->linesize[0] -  avctx->width;
  91.         U += frame->linesize[1] - (avctx->width >> 1);
  92.         V += frame->linesize[2] - (avctx->width >> 1);
  93.     }
  94.  
  95.     *got_frame = 1;
  96.  
  97.     return pkt->size;
  98. }
  99.  
  100. AVCodec ff_aura2_decoder = {
  101.     .name           = "aura2",
  102.     .long_name      = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
  103.     .type           = AVMEDIA_TYPE_VIDEO,
  104.     .id             = AV_CODEC_ID_AURA2,
  105.     .init           = aura_decode_init,
  106.     .decode         = aura_decode_frame,
  107.     .capabilities   = CODEC_CAP_DR1,
  108. };
  109.