1/**
2 * @file
3 * Psygnosis YOP decoder
4 *
5 * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
6 * derived from the code by
7 * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
8 *
9 * This file is part of FFmpeg.
10 *
11 * FFmpeg is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * FFmpeg is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with FFmpeg; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26#include "libavutil/intreadwrite.h"
27
28#include "avcodec.h"
29#include "get_bits.h"
30
31typedef struct YopDecContext {
32    AVFrame frame;
33    AVCodecContext *avctx;
34
35    int num_pal_colors;
36    int first_color[2];
37    int frame_data_length;
38    int row_pos;
39
40    uint8_t *low_nibble;
41    uint8_t *srcptr;
42    uint8_t *dstptr;
43    uint8_t *dstbuf;
44} YopDecContext;
45
46// These tables are taken directly from:
47// http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP
48
49/**
50 * Lookup table for painting macroblocks. Bytes 0-2 of each entry contain
51 * the macroblock positions to be painted (taken as (0, B0, B1, B2)).
52 * Byte 3 contains the number of bytes consumed on the input,
53 * equal to max(bytes 0-2) + 1.
54 */
55static const uint8_t paint_lut[15][4] =
56    {{1, 2, 3, 4}, {1, 2, 0, 3},
57     {1, 2, 1, 3}, {1, 2, 2, 3},
58     {1, 0, 2, 3}, {1, 0, 0, 2},
59     {1, 0, 1, 2}, {1, 1, 2, 3},
60     {0, 1, 2, 3}, {0, 1, 0, 2},
61     {1, 1, 0, 2}, {0, 1, 1, 2},
62     {0, 0, 1, 2}, {0, 0, 0, 1},
63     {1, 1, 1, 2},
64    };
65
66/**
67 * Lookup table for copying macroblocks. Each entry contains the respective
68 * x and y pixel offset for the copy source.
69 */
70static const int8_t motion_vector[16][2] =
71    {{-4, -4}, {-2, -4},
72     { 0, -4}, { 2, -4},
73     {-4, -2}, {-4,  0},
74     {-3, -3}, {-1, -3},
75     { 1, -3}, { 3, -3},
76     {-3, -1}, {-2, -2},
77     { 0, -2}, { 2, -2},
78     { 4, -2}, {-2,  0},
79    };
80
81static av_cold int yop_decode_init(AVCodecContext *avctx)
82{
83    YopDecContext *s = avctx->priv_data;
84    s->avctx = avctx;
85
86    if (avctx->width & 1 || avctx->height & 1 ||
87        avcodec_check_dimensions(avctx, avctx->width, avctx->height) < 0) {
88        av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n");
89        return -1;
90    }
91
92    avctx->pix_fmt = PIX_FMT_PAL8;
93
94    s->num_pal_colors = avctx->extradata[0];
95    s->first_color[0] = avctx->extradata[1];
96    s->first_color[1] = avctx->extradata[2];
97
98    if (s->num_pal_colors + s->first_color[0] > 256 ||
99        s->num_pal_colors + s->first_color[1] > 256) {
100        av_log(avctx, AV_LOG_ERROR,
101               "YOP: palette parameters invalid, header probably corrupt\n");
102        return AVERROR_INVALIDDATA;
103    }
104
105    return 0;
106}
107
108static av_cold int yop_decode_close(AVCodecContext *avctx)
109{
110    YopDecContext *s = avctx->priv_data;
111    if (s->frame.data[0])
112        avctx->release_buffer(avctx, &s->frame);
113    return 0;
114}
115
116/**
117 * Paints a macroblock using the pattern in paint_lut.
118 * @param s codec context
119 * @param tag the tag that was in the nibble
120 */
121static void yop_paint_block(YopDecContext *s, int tag)
122{
123    s->dstptr[0]                        = s->srcptr[0];
124    s->dstptr[1]                        = s->srcptr[paint_lut[tag][0]];
125    s->dstptr[s->frame.linesize[0]]     = s->srcptr[paint_lut[tag][1]];
126    s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]];
127
128    // The number of src bytes consumed is in the last part of the lut entry.
129    s->srcptr += paint_lut[tag][3];
130}
131
132/**
133 * Copies a previously painted macroblock to the current_block.
134 * @param copy_tag the tag that was in the nibble
135 */
136static int yop_copy_previous_block(YopDecContext *s, int copy_tag)
137{
138    uint8_t *bufptr;
139
140    // Calculate position for the copy source
141    bufptr = s->dstptr + motion_vector[copy_tag][0] +
142             s->frame.linesize[0] * motion_vector[copy_tag][1];
143    if (bufptr < s->dstbuf) {
144        av_log(s->avctx, AV_LOG_ERROR,
145               "YOP: cannot decode, file probably corrupt\n");
146        return AVERROR_INVALIDDATA;
147    }
148
149    s->dstptr[0]                        = bufptr[0];
150    s->dstptr[1]                        = bufptr[1];
151    s->dstptr[s->frame.linesize[0]]     = bufptr[s->frame.linesize[0]];
152    s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1];
153
154    return 0;
155}
156
157/**
158 * Returns the next nibble in sequence, consuming a new byte on the input
159 * only if necessary.
160 */
161static uint8_t yop_get_next_nibble(YopDecContext *s)
162{
163    int ret;
164
165    if (s->low_nibble) {
166        ret           = *s->low_nibble & 0xf;
167        s->low_nibble = NULL;
168    }else {
169        s->low_nibble = s->srcptr++;
170        ret           = *s->low_nibble >> 4;
171    }
172    return ret;
173}
174
175/**
176 * Takes s->dstptr to the next macroblock in sequence.
177 */
178static void yop_next_macroblock(YopDecContext *s)
179{
180    // If we are advancing to the next row of macroblocks
181    if (s->row_pos == s->frame.linesize[0] - 2) {
182        s->dstptr  += s->frame.linesize[0];
183        s->row_pos =  0;
184    }else {
185        s->row_pos += 2;
186    }
187    s->dstptr += 2;
188}
189
190static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
191                            AVPacket *avpkt)
192{
193    YopDecContext *s = avctx->priv_data;
194    int tag, firstcolor, is_odd_frame;
195    int ret, i;
196    uint32_t *palette;
197
198    if (s->frame.data[0])
199        avctx->release_buffer(avctx, &s->frame);
200
201    ret = avctx->get_buffer(avctx, &s->frame);
202    if (ret < 0) {
203        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
204        return ret;
205    }
206
207    s->frame.linesize[0] = avctx->width;
208
209    s->dstbuf     = s->frame.data[0];
210    s->dstptr     = s->frame.data[0];
211    s->srcptr     = avpkt->data + 4;
212    s->row_pos    = 0;
213    s->low_nibble = NULL;
214
215    is_odd_frame = avpkt->data[0];
216    firstcolor   = s->first_color[is_odd_frame];
217    palette      = (uint32_t *)s->frame.data[1];
218
219    for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
220        palette[i + firstcolor] = (s->srcptr[0] << 18) |
221                                  (s->srcptr[1] << 10) |
222                                  (s->srcptr[2] << 2);
223
224    s->frame.palette_has_changed = 1;
225
226    while (s->dstptr - s->dstbuf <
227           avctx->width * avctx->height &&
228           s->srcptr - avpkt->data < avpkt->size) {
229
230        tag = yop_get_next_nibble(s);
231
232        if (tag != 0xf) {
233            yop_paint_block(s, tag);
234        }else {
235            tag = yop_get_next_nibble(s);
236            ret = yop_copy_previous_block(s, tag);
237            if (ret < 0) {
238                avctx->release_buffer(avctx, &s->frame);
239                return ret;
240            }
241        }
242        yop_next_macroblock(s);
243    }
244
245    *data_size        = sizeof(AVFrame);
246    *(AVFrame *) data = s->frame;
247    return avpkt->size;
248}
249
250AVCodec yop_decoder = {
251    "yop",
252    AVMEDIA_TYPE_VIDEO,
253    CODEC_ID_YOP,
254    sizeof(YopDecContext),
255    yop_decode_init,
256    NULL,
257    yop_decode_close,
258    yop_decode_frame,
259    .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
260};
261