2 * Escape 130 Video Decoder
3 * Copyright (C) 2008 Eli Friedman (eli.friedman <at> gmail.com)
5 * This file is part of FFmpeg.
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #define BITSTREAM_READER_LE
29 typedef struct Escape130Context {
35 * Initialize the decoder
36 * @param avctx decoder context
37 * @return 0 success, negative on error
39 static av_cold int escape130_decode_init(AVCodecContext *avctx)
41 Escape130Context *s = avctx->priv_data;
42 avctx->pix_fmt = AV_PIX_FMT_YUV420P;
44 if((avctx->width&1) || (avctx->height&1)){
45 av_log(avctx, AV_LOG_ERROR, "Dimensions are not a multiple of the block size\n");
46 return AVERROR(EINVAL);
49 s->bases= av_malloc(avctx->width * avctx->height /4);
54 static av_cold int escape130_decode_close(AVCodecContext *avctx)
56 Escape130Context *s = avctx->priv_data;
59 avctx->release_buffer(avctx, &s->frame);
66 static unsigned decode_skip_count(GetBitContext* gb) {
68 // This function reads a maximum of 27 bits,
69 // which is within the padding space
70 if (get_bits_left(gb) < 1+3)
73 value = get_bits1(gb);
77 value = get_bits(gb, 3);
81 value = get_bits(gb, 8);
85 value = get_bits(gb, 15);
93 * Decode a single frame
94 * @param avctx decoder context
95 * @param data decoded frame
96 * @param got_frame have decoded frame
97 * @param buf input buffer
98 * @param buf_size input buffer size
99 * @return 0 success, -1 on error
101 static int escape130_decode_frame(AVCodecContext *avctx,
102 void *data, int *got_frame,
105 const uint8_t *buf = avpkt->data;
106 int buf_size = avpkt->size;
107 Escape130Context *s = avctx->priv_data;
112 uint8_t *old_y, *old_cb, *old_cr,
113 *new_y, *new_cb, *new_cr;
114 unsigned old_y_stride, old_cb_stride, old_cr_stride,
115 new_y_stride, new_cb_stride, new_cr_stride;
116 unsigned total_blocks = avctx->width * avctx->height / 4,
117 block_index, row_index = 0;
118 unsigned y[4] = {0}, cb = 16, cr = 16;
121 uint8_t *yb= s->bases;
123 AVFrame new_frame = { { 0 } };
125 init_get_bits(&gb, buf, buf_size * 8);
127 if (get_bits_left(&gb) < 128)
130 // Header; no useful information in here
131 skip_bits_long(&gb, 128);
133 new_frame.reference = 3;
134 if (ff_get_buffer(avctx, &new_frame)) {
135 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
139 new_y = new_frame.data[0];
140 new_cb = new_frame.data[1];
141 new_cr = new_frame.data[2];
142 new_y_stride = new_frame.linesize[0];
143 new_cb_stride = new_frame.linesize[1];
144 new_cr_stride = new_frame.linesize[2];
145 old_y = s->frame.data[0];
146 old_cb = s->frame.data[1];
147 old_cr = s->frame.data[2];
148 old_y_stride = s->frame.linesize[0];
149 old_cb_stride = s->frame.linesize[1];
150 old_cr_stride = s->frame.linesize[2];
152 av_log(avctx, AV_LOG_DEBUG,
154 new_y_stride, new_cb_stride);
156 for (block_index = 0; block_index < total_blocks; block_index++) {
157 // Note that this call will make us skip the rest of the blocks
158 // if the frame prematurely ends
160 skip = decode_skip_count(&gb);
166 y[2] = old_y[old_y_stride] / 4;
167 y[3] = old_y[old_y_stride+1] / 4;
172 y_base=y[0] = y[1] = y[2] = y[3] = 0;
176 if (get_bits1(&gb)) {
177 static const uint8_t offset_table[] = {2, 4, 10, 20};
178 static const int8_t sign_table[64][4] =
236 unsigned sign_selector = get_bits(&gb, 6);
237 unsigned difference_selector = get_bits(&gb, 2);
238 y_base = 2 * get_bits(&gb, 5);
239 for (i = 0; i < 4; i++) {
240 y[i] = av_clip((int)y_base + offset_table[difference_selector] *
241 sign_table[sign_selector][i], 0, 63);
243 } else if (get_bits1(&gb)) {
244 if (get_bits1(&gb)) {
245 y_base = get_bits(&gb, 6);
247 unsigned adjust_index = get_bits(&gb, 3);
248 static const int8_t adjust[] = {-4, -3, -2, -1, 1, 2, 3, 4};
249 y_base = (y_base + adjust[adjust_index]) & 63;
251 for (i = 0; i < 4; i++)
255 if (get_bits1(&gb)) {
256 if (get_bits1(&gb)) {
257 cb = get_bits(&gb, 5);
258 cr = get_bits(&gb, 5);
260 unsigned adjust_index = get_bits(&gb, 3);
261 static const int8_t adjust[2][8] =
262 { { 1, 1, 0, -1, -1, -1, 0, 1 },
263 { 0, 1, 1, 1, 0, -1, -1, -1 } };
264 cb = (cb + adjust[0][adjust_index]) & 31;
265 cr = (cr + adjust[1][adjust_index]) & 31;
273 new_y[new_y_stride] = y[2] * 4;
274 new_y[new_y_stride + 1] = y[3] * 4;
279 old_y += 2, old_cb++, old_cr++;
280 new_y += 2, new_cb++, new_cr++;
282 if (avctx->width / 2 == row_index) {
285 old_y += old_y_stride * 2 - avctx->width;
286 old_cb += old_cb_stride - avctx->width / 2;
287 old_cr += old_cr_stride - avctx->width / 2;
289 new_y += new_y_stride * 2 - avctx->width;
290 new_cb += new_cb_stride - avctx->width / 2;
291 new_cr += new_cr_stride - avctx->width / 2;
297 av_log(avctx, AV_LOG_DEBUG,
298 "Escape sizes: %i, %i\n",
299 buf_size, get_bits_count(&gb) / 8);
301 if (s->frame.data[0])
302 avctx->release_buffer(avctx, &s->frame);
304 *(AVFrame*)data = s->frame = new_frame;
311 AVCodec ff_escape130_decoder = {
313 .type = AVMEDIA_TYPE_VIDEO,
314 .id = AV_CODEC_ID_ESCAPE130,
315 .priv_data_size = sizeof(Escape130Context),
316 .init = escape130_decode_init,
317 .close = escape130_decode_close,
318 .decode = escape130_decode_frame,
319 .capabilities = CODEC_CAP_DR1,
320 .long_name = NULL_IF_CONFIG_SMALL("Escape 130"),