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
  28 typedef struct AuraDecodeContext {
  29     AVCodecContext *avctx;
  30     AVFrame frame;
  31 } AuraDecodeContext;
  32
  33 static av_cold int aura_decode_init(AVCodecContext *avctx)
  34 {
  35     AuraDecodeContext *s = avctx->priv_data;
  36
  37     s->avctx = avctx;
  38     /* width needs to be divisible by 4 for this codec to work */
  39     if (avctx->width & 0x3)
  40         return -1;
  41     avctx->pix_fmt = PIX_FMT_YUV422P;
  42
  43     return 0;
  44 }
  45
  46 static int aura_decode_frame(AVCodecContext *avctx,
  47                              void *data, int *data_size,
  48                              AVPacket *pkt)
  49 {
  50     AuraDecodeContext *s=avctx->priv_data;
  51
  52     uint8_t *Y, *U, *V;
  53     uint8_t val;
  54     int x, y;
  55     const uint8_t *buf = pkt->data;
  56
  57     /* prediction error tables (make it clear that they are signed values) */
  58     const int8_t *delta_table = (const int8_t*)buf + 16;
  59
  60     if (pkt->size != 48 + avctx->height * avctx->width) {
  61         av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
  62                pkt->size, 48 + avctx->height * avctx->width);
  63         return -1;
  64     }
  65
  66     /* pixel data starts 48 bytes in, after 3x16-byte tables */
  67     buf += 48;
  68
  69     if(s->frame.data[0])
  70         avctx->release_buffer(avctx, &s->frame);
  71
  72     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
  73     s->frame.reference = 0;
  74     if(avctx->get_buffer(avctx, &s->frame) < 0) {
  75         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  76         return -1;
  77     }
  78
  79     Y = s->frame.data[0];
  80     U = s->frame.data[1];
  81     V = s->frame.data[2];
  82
  83     /* iterate through each line in the height */
  84     for (y = 0; y < avctx->height; y++) {
  85         /* reset predictors */
  86         val = *buf++;
  87         U[0] = val & 0xF0;
  88         Y[0] = val << 4;
  89         val = *buf++;
  90         V[0] = val & 0xF0;
  91         Y[1] = Y[0] + delta_table[val & 0xF];
  92         Y += 2; U++; V++;
  93
  94         /* iterate through the remaining pixel groups (4 pixels/group) */
  95         for (x = 1; x < (avctx->width >> 1); x++) {
  96             val = *buf++;
  97             U[0] = U[-1] + delta_table[val >> 4];
  98             Y[0] = Y[-1] + delta_table[val & 0xF];
  99             val = *buf++;
 100             V[0] = V[-1] + delta_table[val >> 4];
 101             Y[1] = Y[ 0] + delta_table[val & 0xF];
 102             Y += 2; U++; V++;
 103         }
 104         Y += s->frame.linesize[0] -  avctx->width;
 105         U += s->frame.linesize[1] - (avctx->width >> 1);
 106         V += s->frame.linesize[2] - (avctx->width >> 1);
 107     }
 108
 109     *data_size=sizeof(AVFrame);
 110     *(AVFrame*)data= s->frame;
 111
 112     return pkt->size;
 113 }
 114
 115 static av_cold int aura_decode_end(AVCodecContext *avctx)
 116 {
 117     AuraDecodeContext *s = avctx->priv_data;
 118
 119     if (s->frame.data[0])
 120         avctx->release_buffer(avctx, &s->frame);
 121
 122     return 0;
 123 }
 124
 125 AVCodec ff_aura2_decoder = {
 126     .name           = "aura2",
 127     .type           = AVMEDIA_TYPE_VIDEO,
 128     .id             = CODEC_ID_AURA2,
 129     .priv_data_size = sizeof(AuraDecodeContext),
 130     .init           = aura_decode_init,
 131     .close          = aura_decode_end,
 132     .decode         = aura_decode_frame,
 133     .capabilities   = CODEC_CAP_DR1,
 134     .long_name      = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
 135 };