2 * Wing Commander/Xan Video Decoder
3 * Copyright (C) 2011 Konstantin Shishkov
4 * based on work by Mike Melanson
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "libavutil/intreadwrite.h"
25 #include "libavutil/mem.h"
26 #include "bytestream.h"
27 #define BITSTREAM_READER_LE
31 typedef struct XanContext {
32 AVCodecContext *avctx;
36 uint8_t *scratch_buffer;
41 static av_cold int xan_decode_end(AVCodecContext *avctx);
43 static av_cold int xan_decode_init(AVCodecContext *avctx)
45 XanContext *s = avctx->priv_data;
49 avctx->pix_fmt = AV_PIX_FMT_YUV420P;
51 if (avctx->height < 8) {
52 av_log(avctx, AV_LOG_ERROR, "Invalid frame height: %d.\n", avctx->height);
53 return AVERROR(EINVAL);
56 s->buffer_size = avctx->width * avctx->height;
57 s->y_buffer = av_malloc(s->buffer_size);
59 return AVERROR(ENOMEM);
60 s->scratch_buffer = av_malloc(s->buffer_size + 130);
61 if (!s->scratch_buffer) {
62 xan_decode_end(avctx);
63 return AVERROR(ENOMEM);
66 s->pic = av_frame_alloc();
68 xan_decode_end(avctx);
69 return AVERROR(ENOMEM);
75 static int xan_unpack_luma(XanContext *s,
76 uint8_t *dst, const int dst_size)
81 const uint8_t *dst_end = dst + dst_size;
82 GetByteContext tree = s->gb;
83 int start_off = bytestream2_tell(&tree);
85 tree_size = bytestream2_get_byte(&s->gb);
86 eof = bytestream2_get_byte(&s->gb);
87 tree_root = eof + tree_size;
88 bytestream2_skip(&s->gb, tree_size * 2);
91 bits = bytestream2_get_byte(&s->gb);
94 int bit = !!(bits & mask);
96 bytestream2_seek(&tree, start_off + node*2 + bit - eof * 2, SEEK_SET);
97 node = bytestream2_get_byte(&tree);
107 if (bytestream2_get_bytes_left(&s->gb) <= 0)
109 bits = bytestream2_get_byteu(&s->gb);
113 return dst != dst_end ? AVERROR_INVALIDDATA : 0;
116 /* almost the same as in xan_wc3 decoder */
117 static int xan_unpack(XanContext *s,
118 uint8_t *dest, const int dest_len)
122 uint8_t *orig_dest = dest;
123 const uint8_t *dest_end = dest + dest_len;
125 while (dest < dest_end) {
126 if (bytestream2_get_bytes_left(&s->gb) <= 0)
127 return AVERROR_INVALIDDATA;
129 opcode = bytestream2_get_byteu(&s->gb);
133 if ((opcode & 0x80) == 0) {
135 back = ((opcode & 0x60) << 3) + bytestream2_get_byte(&s->gb) + 1;
136 size2 = ((opcode & 0x1c) >> 2) + 3;
137 } else if ((opcode & 0x40) == 0) {
138 size = bytestream2_peek_byte(&s->gb) >> 6;
139 back = (bytestream2_get_be16(&s->gb) & 0x3fff) + 1;
140 size2 = (opcode & 0x3f) + 4;
143 back = ((opcode & 0x10) << 12) + bytestream2_get_be16(&s->gb) + 1;
144 size2 = ((opcode & 0x0c) << 6) + bytestream2_get_byte(&s->gb) + 5;
145 if (size + size2 > dest_end - dest)
148 if (dest + size + size2 > dest_end ||
149 dest - orig_dest + size < back)
150 return AVERROR_INVALIDDATA;
151 bytestream2_get_buffer(&s->gb, dest, size);
153 av_memcpy_backptr(dest, back, size2);
156 int finish = opcode >= 0xfc;
158 size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
159 if (dest_end - dest < size)
160 return AVERROR_INVALIDDATA;
161 bytestream2_get_buffer(&s->gb, dest, size);
167 return dest - orig_dest;
170 static int xan_decode_chroma(AVCodecContext *avctx, unsigned chroma_off)
172 XanContext *s = avctx->priv_data;
176 const uint8_t *src, *src_end;
177 const uint8_t *table;
178 int mode, offset, dec_size, table_size;
182 if (chroma_off + 4 >= bytestream2_get_bytes_left(&s->gb)) {
183 av_log(avctx, AV_LOG_ERROR, "Invalid chroma block position\n");
184 return AVERROR_INVALIDDATA;
186 bytestream2_seek(&s->gb, chroma_off + 4, SEEK_SET);
187 mode = bytestream2_get_le16(&s->gb);
188 table = s->gb.buffer;
189 table_size = bytestream2_get_le16(&s->gb);
190 offset = table_size * 2;
193 if (offset >= bytestream2_get_bytes_left(&s->gb)) {
194 av_log(avctx, AV_LOG_ERROR, "Invalid chroma block offset\n");
195 return AVERROR_INVALIDDATA;
198 bytestream2_skip(&s->gb, offset);
199 memset(s->scratch_buffer, 0, s->buffer_size);
200 dec_size = xan_unpack(s, s->scratch_buffer, s->buffer_size);
202 av_log(avctx, AV_LOG_ERROR, "Chroma unpacking failed\n");
208 src = s->scratch_buffer;
209 src_end = src + dec_size;
211 for (j = 0; j < avctx->height >> 1; j++) {
212 for (i = 0; i < avctx->width >> 1; i++) {
213 if (src_end - src < 1)
217 if (val >= table_size)
218 return AVERROR_INVALIDDATA;
219 val = AV_RL16(table + (val << 1));
220 uval = (val >> 3) & 0xF8;
221 vval = (val >> 8) & 0xF8;
222 U[i] = uval | (uval >> 5);
223 V[i] = vval | (vval >> 5);
226 U += s->pic->linesize[1];
227 V += s->pic->linesize[2];
229 if (avctx->height & 1) {
230 memcpy(U, U - s->pic->linesize[1], avctx->width >> 1);
231 memcpy(V, V - s->pic->linesize[2], avctx->width >> 1);
234 uint8_t *U2 = U + s->pic->linesize[1];
235 uint8_t *V2 = V + s->pic->linesize[2];
237 for (j = 0; j < avctx->height >> 2; j++) {
238 for (i = 0; i < avctx->width >> 1; i += 2) {
239 if (src_end - src < 1)
243 if (val >= table_size)
244 return AVERROR_INVALIDDATA;
245 val = AV_RL16(table + (val << 1));
246 uval = (val >> 3) & 0xF8;
247 vval = (val >> 8) & 0xF8;
248 U[i] = U[i+1] = U2[i] = U2[i+1] = uval | (uval >> 5);
249 V[i] = V[i+1] = V2[i] = V2[i+1] = vval | (vval >> 5);
252 U += s->pic->linesize[1] * 2;
253 V += s->pic->linesize[2] * 2;
254 U2 += s->pic->linesize[1] * 2;
255 V2 += s->pic->linesize[2] * 2;
257 if (avctx->height & 3) {
258 int lines = ((avctx->height + 1) >> 1) - (avctx->height >> 2) * 2;
260 memcpy(U, U - lines * s->pic->linesize[1], lines * s->pic->linesize[1]);
261 memcpy(V, V - lines * s->pic->linesize[2], lines * s->pic->linesize[2]);
268 static int xan_decode_frame_type0(AVCodecContext *avctx)
270 XanContext *s = avctx->priv_data;
271 uint8_t *ybuf, *prev_buf, *src = s->scratch_buffer;
272 unsigned chroma_off, corr_off;
277 chroma_off = bytestream2_get_le32(&s->gb);
278 corr_off = bytestream2_get_le32(&s->gb);
280 if ((ret = xan_decode_chroma(avctx, chroma_off)) != 0)
283 if (corr_off >= bytestream2_size(&s->gb)) {
284 av_log(avctx, AV_LOG_WARNING, "Ignoring invalid correction block position\n");
287 bytestream2_seek(&s->gb, 12, SEEK_SET);
288 ret = xan_unpack_luma(s, src, s->buffer_size >> 1);
290 av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");
297 for (j = 1; j < avctx->width - 1; j += 2) {
298 cur = (last + *src++) & 0x1F;
299 ybuf[j] = last + cur;
300 ybuf[j+1] = cur << 1;
306 ybuf += avctx->width;
308 for (i = 1; i < avctx->height; i++) {
309 last = ((prev_buf[0] >> 1) + *src++) & 0x1F;
311 for (j = 1; j < avctx->width - 1; j += 2) {
312 cur = ((prev_buf[j + 1] >> 1) + *src++) & 0x1F;
313 ybuf[j] = last + cur;
314 ybuf[j+1] = cur << 1;
320 ybuf += avctx->width;
326 bytestream2_seek(&s->gb, 8 + corr_off, SEEK_SET);
327 dec_size = xan_unpack(s, s->scratch_buffer, s->buffer_size / 2);
331 dec_size = FFMIN(dec_size, s->buffer_size/2 - 1);
333 for (i = 0; i < dec_size; i++)
334 s->y_buffer[i*2+1] = (s->y_buffer[i*2+1] + (s->scratch_buffer[i] << 1)) & 0x3F;
338 ybuf = s->pic->data[0];
339 for (j = 0; j < avctx->height; j++) {
340 for (i = 0; i < avctx->width; i++)
341 ybuf[i] = (src[i] << 2) | (src[i] >> 3);
343 ybuf += s->pic->linesize[0];
349 static int xan_decode_frame_type1(AVCodecContext *avctx)
351 XanContext *s = avctx->priv_data;
352 uint8_t *ybuf, *src = s->scratch_buffer;
357 if ((ret = xan_decode_chroma(avctx, bytestream2_get_le32(&s->gb))) != 0)
360 bytestream2_seek(&s->gb, 16, SEEK_SET);
361 ret = xan_unpack_luma(s, src,
362 s->buffer_size >> 1);
364 av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");
369 for (i = 0; i < avctx->height; i++) {
370 last = (ybuf[0] + (*src++ << 1)) & 0x3F;
372 for (j = 1; j < avctx->width - 1; j += 2) {
373 cur = (ybuf[j + 1] + (*src++ << 1)) & 0x3F;
374 ybuf[j] = (last + cur) >> 1;
380 ybuf += avctx->width;
384 ybuf = s->pic->data[0];
385 for (j = 0; j < avctx->height; j++) {
386 for (i = 0; i < avctx->width; i++)
387 ybuf[i] = (src[i] << 2) | (src[i] >> 3);
389 ybuf += s->pic->linesize[0];
395 static int xan_decode_frame(AVCodecContext *avctx,
396 void *data, int *got_frame,
399 XanContext *s = avctx->priv_data;
403 if ((ret = ff_reget_buffer(avctx, s->pic)) < 0)
406 bytestream2_init(&s->gb, avpkt->data, avpkt->size);
407 ftype = bytestream2_get_le32(&s->gb);
410 ret = xan_decode_frame_type0(avctx);
413 ret = xan_decode_frame_type1(avctx);
416 av_log(avctx, AV_LOG_ERROR, "Unknown frame type %d\n", ftype);
417 return AVERROR_INVALIDDATA;
422 if ((ret = av_frame_ref(data, s->pic)) < 0)
430 static av_cold int xan_decode_end(AVCodecContext *avctx)
432 XanContext *s = avctx->priv_data;
434 av_frame_free(&s->pic);
436 av_freep(&s->y_buffer);
437 av_freep(&s->scratch_buffer);
442 AVCodec ff_xan_wc4_decoder = {
444 .type = AVMEDIA_TYPE_VIDEO,
445 .id = AV_CODEC_ID_XAN_WC4,
446 .priv_data_size = sizeof(XanContext),
447 .init = xan_decode_init,
448 .close = xan_decode_end,
449 .decode = xan_decode_frame,
450 .capabilities = CODEC_CAP_DR1,
451 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander IV / Xxan"),