libavcodec/aura.c

   1 /*
   2  * Aura 2 decoder
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav 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  * Libav 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 Libav; 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         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  64         return ret;
  65     }
  66
  67     Y = frame->data[0];
  68     U = frame->data[1];
  69     V = frame->data[2];
  70
  71     /* iterate through each line in the height */
  72     for (y = 0; y < avctx->height; y++) {
  73         /* reset predictors */
  74         val  = *buf++;
  75         U[0] = val & 0xF0;
  76         Y[0] = val << 4;
  77         val  = *buf++;
  78         V[0] = val & 0xF0;
  79         Y[1] = Y[0] + delta_table[val & 0xF];
  80         Y   += 2; U++; V++;
  81
  82         /* iterate through the remaining pixel groups (4 pixels/group) */
  83         for (x = 1; x < (avctx->width >> 1); x++) {
  84             val  = *buf++;
  85             U[0] = U[-1] + delta_table[val >> 4];
  86             Y[0] = Y[-1] + delta_table[val & 0xF];
  87             val  = *buf++;
  88             V[0] = V[-1] + delta_table[val >> 4];
  89             Y[1] = Y[ 0] + delta_table[val & 0xF];
  90             Y   += 2; U++; V++;
  91         }
  92         Y += frame->linesize[0] -  avctx->width;
  93         U += frame->linesize[1] - (avctx->width >> 1);
  94         V += frame->linesize[2] - (avctx->width >> 1);
  95     }
  96
  97     *got_frame = 1;
  98
  99     return pkt->size;
 100 }
 101
 102 AVCodec ff_aura2_decoder = {
 103     .name           = "aura2",
 104     .long_name      = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
 105     .type           = AVMEDIA_TYPE_VIDEO,
 106     .id             = AV_CODEC_ID_AURA2,
 107     .init           = aura_decode_init,
 108     .decode         = aura_decode_frame,
 109     .capabilities   = AV_CODEC_CAP_DR1,
 110     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
 111 };