libavcodec/aura.c

   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 "codec_internal.h"
  28 #include "decode.h"
  29 #include "libavutil/internal.h"
  30
  31 static av_cold int aura_decode_init(AVCodecContext *avctx)
  32 {
  33     /* width needs to be divisible by 4 for this codec to work */
  34     if (avctx->width & 0x3)
  35         return AVERROR(EINVAL);
  36     avctx->pix_fmt = AV_PIX_FMT_YUV422P;
  37
  38     return 0;
  39 }
  40
  41 static int aura_decode_frame(AVCodecContext *avctx, AVFrame *frame,
  42                              int *got_frame, AVPacket *pkt)
  43 {
  44     uint8_t *Y, *U, *V;
  45     uint8_t val;
  46     int x, y, ret;
  47     const uint8_t *buf = pkt->data;
  48
  49     /* prediction error tables (make it clear that they are signed values) */
  50     const int8_t *delta_table = (const int8_t*)buf + 16;
  51
  52     if (pkt->size != 48 + avctx->height * avctx->width) {
  53         av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
  54                pkt->size, 48 + avctx->height * avctx->width);
  55         return AVERROR_INVALIDDATA;
  56     }
  57
  58     /* pixel data starts 48 bytes in, after 3x16-byte tables */
  59     buf += 48;
  60
  61     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  62         return ret;
  63
  64     Y = frame->data[0];
  65     U = frame->data[1];
  66     V = frame->data[2];
  67
  68     /* iterate through each line in the height */
  69     for (y = 0; y < avctx->height; y++) {
  70         /* reset predictors */
  71         val  = *buf++;
  72         U[0] = val & 0xF0;
  73         Y[0] = val << 4;
  74         val  = *buf++;
  75         V[0] = val & 0xF0;
  76         Y[1] = Y[0] + delta_table[val & 0xF];
  77         Y   += 2; U++; V++;
  78
  79         /* iterate through the remaining pixel groups (4 pixels/group) */
  80         for (x = 1; x < (avctx->width >> 1); x++) {
  81             val  = *buf++;
  82             U[0] = U[-1] + delta_table[val >> 4];
  83             Y[0] = Y[-1] + delta_table[val & 0xF];
  84             val  = *buf++;
  85             V[0] = V[-1] + delta_table[val >> 4];
  86             Y[1] = Y[ 0] + delta_table[val & 0xF];
  87             Y   += 2; U++; V++;
  88         }
  89         Y += frame->linesize[0] -  avctx->width;
  90         U += frame->linesize[1] - (avctx->width >> 1);
  91         V += frame->linesize[2] - (avctx->width >> 1);
  92     }
  93
  94     *got_frame = 1;
  95
  96     return pkt->size;
  97 }
  98
  99 const FFCodec ff_aura2_decoder = {
 100     .p.name         = "aura2",
 101     CODEC_LONG_NAME("Auravision Aura 2"),
 102     .p.type         = AVMEDIA_TYPE_VIDEO,
 103     .p.id           = AV_CODEC_ID_AURA2,
 104     .init           = aura_decode_init,
 105     FF_CODEC_DECODE_CB(aura_decode_frame),
 106     .p.capabilities = AV_CODEC_CAP_DR1,
 107 };