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 typedef struct AuraDecodeContext {
  31     AVCodecContext *avctx;
  32     AVFrame frame;
  33 } AuraDecodeContext;
  34
  35 static av_cold int aura_decode_init(AVCodecContext *avctx)
  36 {
  37     AuraDecodeContext *s = avctx->priv_data;
  38
  39     s->avctx = avctx;
  40     /* width needs to be divisible by 4 for this codec to work */
  41     if (avctx->width & 0x3)
  42         return AVERROR(EINVAL);
  43     avctx->pix_fmt = AV_PIX_FMT_YUV422P;
  44
  45     return 0;
  46 }
  47
  48 static int aura_decode_frame(AVCodecContext *avctx,
  49                              void *data, int *got_frame,
  50                              AVPacket *pkt)
  51 {
  52     AuraDecodeContext *s = avctx->priv_data;
  53     uint8_t *Y, *U, *V;
  54     uint8_t val;
  55     int x, y, ret;
  56     const uint8_t *buf = pkt->data;
  57
  58     /* prediction error tables (make it clear that they are signed values) */
  59     const int8_t *delta_table = (const int8_t*)buf + 16;
  60
  61     if (pkt->size != 48 + avctx->height * avctx->width) {
  62         av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
  63                pkt->size, 48 + avctx->height * avctx->width);
  64         return AVERROR_INVALIDDATA;
  65     }
  66
  67     /* pixel data starts 48 bytes in, after 3x16-byte tables */
  68     buf += 48;
  69
  70     if (s->frame.data[0])
  71         avctx->release_buffer(avctx, &s->frame);
  72
  73     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;
  74     s->frame.reference = 0;
  75     if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
  76         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
  77         return ret;
  78     }
  79
  80     Y = s->frame.data[0];
  81     U = s->frame.data[1];
  82     V = s->frame.data[2];
  83
  84     /* iterate through each line in the height */
  85     for (y = 0; y < avctx->height; y++) {
  86         /* reset predictors */
  87         val  = *buf++;
  88         U[0] = val & 0xF0;
  89         Y[0] = val << 4;
  90         val  = *buf++;
  91         V[0] = val & 0xF0;
  92         Y[1] = Y[0] + delta_table[val & 0xF];
  93         Y   += 2; U++; V++;
  94
  95         /* iterate through the remaining pixel groups (4 pixels/group) */
  96         for (x = 1; x < (avctx->width >> 1); x++) {
  97             val  = *buf++;
  98             U[0] = U[-1] + delta_table[val >> 4];
  99             Y[0] = Y[-1] + delta_table[val & 0xF];
 100             val  = *buf++;
 101             V[0] = V[-1] + delta_table[val >> 4];
 102             Y[1] = Y[ 0] + delta_table[val & 0xF];
 103             Y   += 2; U++; V++;
 104         }
 105         Y += s->frame.linesize[0] -  avctx->width;
 106         U += s->frame.linesize[1] - (avctx->width >> 1);
 107         V += s->frame.linesize[2] - (avctx->width >> 1);
 108     }
 109
 110     *got_frame = 1;
 111     *(AVFrame*)data = s->frame;
 112
 113     return pkt->size;
 114 }
 115
 116 static av_cold int aura_decode_end(AVCodecContext *avctx)
 117 {
 118     AuraDecodeContext *s = avctx->priv_data;
 119
 120     if (s->frame.data[0])
 121         avctx->release_buffer(avctx, &s->frame);
 122
 123     return 0;
 124 }
 125
 126 AVCodec ff_aura2_decoder = {
 127     .name           = "aura2",
 128     .type           = AVMEDIA_TYPE_VIDEO,
 129     .id             = AV_CODEC_ID_AURA2,
 130     .priv_data_size = sizeof(AuraDecodeContext),
 131     .init           = aura_decode_init,
 132     .close          = aura_decode_end,
 133     .decode         = aura_decode_frame,
 134     .capabilities   = CODEC_CAP_DR1,
 135     .long_name      = NULL_IF_CONFIG_SMALL("Auravision Aura 2"),
 136 };