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
30static 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
40static 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
100AVCodec 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