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 Libav.
8 * Libav 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 * Libav 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 Libav; 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_init(AVCodecContext *avctx)
43 XanContext *s = avctx->priv_data;
47 avctx->pix_fmt = AV_PIX_FMT_YUV420P;
49 if (avctx->height < 8) {
50 av_log(avctx, AV_LOG_ERROR, "Invalid frame height: %d.\n", avctx->height);
51 return AVERROR(EINVAL);
54 s->buffer_size = avctx->width * avctx->height;
55 s->y_buffer = av_malloc(s->buffer_size);
57 return AVERROR(ENOMEM);
58 s->scratch_buffer = av_malloc(s->buffer_size + 130);
59 if (!s->scratch_buffer) {
60 av_freep(&s->y_buffer);
61 return AVERROR(ENOMEM);
67 static int xan_unpack_luma(XanContext *s,
68 uint8_t *dst, const int dst_size)
73 const uint8_t *dst_end = dst + dst_size;
74 GetByteContext tree = s->gb;
75 int start_off = bytestream2_tell(&tree);
77 tree_size = bytestream2_get_byte(&s->gb);
78 eof = bytestream2_get_byte(&s->gb);
79 tree_root = eof + tree_size;
80 bytestream2_skip(&s->gb, tree_size * 2);
83 bits = bytestream2_get_byte(&s->gb);
86 int bit = !!(bits & mask);
88 bytestream2_seek(&tree, start_off + node*2 + bit - eof * 2, SEEK_SET);
89 node = bytestream2_get_byte(&tree);
99 if (bytestream2_get_bytes_left(&s->gb) <= 0)
101 bits = bytestream2_get_byteu(&s->gb);
105 return dst != dst_end ? AVERROR_INVALIDDATA : 0;
108 /* almost the same as in xan_wc3 decoder */
109 static int xan_unpack(XanContext *s,
110 uint8_t *dest, const int dest_len)
114 uint8_t *orig_dest = dest;
115 const uint8_t *dest_end = dest + dest_len;
117 while (dest < dest_end) {
118 if (bytestream2_get_bytes_left(&s->gb) <= 0)
119 return AVERROR_INVALIDDATA;
121 opcode = bytestream2_get_byteu(&s->gb);
125 if ((opcode & 0x80) == 0) {
127 back = ((opcode & 0x60) << 3) + bytestream2_get_byte(&s->gb) + 1;
128 size2 = ((opcode & 0x1c) >> 2) + 3;
129 } else if ((opcode & 0x40) == 0) {
130 size = bytestream2_peek_byte(&s->gb) >> 6;
131 back = (bytestream2_get_be16(&s->gb) & 0x3fff) + 1;
132 size2 = (opcode & 0x3f) + 4;
135 back = ((opcode & 0x10) << 12) + bytestream2_get_be16(&s->gb) + 1;
136 size2 = ((opcode & 0x0c) << 6) + bytestream2_get_byte(&s->gb) + 5;
137 if (size + size2 > dest_end - dest)
140 if (dest + size + size2 > dest_end ||
141 dest - orig_dest + size < back)
142 return AVERROR_INVALIDDATA;
143 bytestream2_get_buffer(&s->gb, dest, size);
145 av_memcpy_backptr(dest, back, size2);
148 int finish = opcode >= 0xfc;
150 size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4;
151 if (dest_end - dest < size)
152 return AVERROR_INVALIDDATA;
153 bytestream2_get_buffer(&s->gb, dest, size);
159 return dest - orig_dest;
162 static int xan_decode_chroma(AVCodecContext *avctx, unsigned chroma_off)
164 XanContext *s = avctx->priv_data;
168 const uint8_t *src, *src_end;
169 const uint8_t *table;
170 int mode, offset, dec_size, table_size;
174 if (chroma_off + 4 >= bytestream2_get_bytes_left(&s->gb)) {
175 av_log(avctx, AV_LOG_ERROR, "Invalid chroma block position\n");
176 return AVERROR_INVALIDDATA;
178 bytestream2_seek(&s->gb, chroma_off + 4, SEEK_SET);
179 mode = bytestream2_get_le16(&s->gb);
180 table = s->gb.buffer;
181 table_size = bytestream2_get_le16(&s->gb);
182 offset = table_size * 2;
185 if (offset >= bytestream2_get_bytes_left(&s->gb)) {
186 av_log(avctx, AV_LOG_ERROR, "Invalid chroma block offset\n");
187 return AVERROR_INVALIDDATA;
190 bytestream2_skip(&s->gb, offset);
191 memset(s->scratch_buffer, 0, s->buffer_size);
192 dec_size = xan_unpack(s, s->scratch_buffer, s->buffer_size);
194 av_log(avctx, AV_LOG_ERROR, "Chroma unpacking failed\n");
200 src = s->scratch_buffer;
201 src_end = src + dec_size;
203 for (j = 0; j < avctx->height >> 1; j++) {
204 for (i = 0; i < avctx->width >> 1; i++) {
206 if (val && val < table_size) {
207 val = AV_RL16(table + (val << 1));
208 uval = (val >> 3) & 0xF8;
209 vval = (val >> 8) & 0xF8;
210 U[i] = uval | (uval >> 5);
211 V[i] = vval | (vval >> 5);
216 U += s->pic.linesize[1];
217 V += s->pic.linesize[2];
219 if (avctx->height & 1) {
220 memcpy(U, U - s->pic.linesize[1], avctx->width >> 1);
221 memcpy(V, V - s->pic.linesize[2], avctx->width >> 1);
224 uint8_t *U2 = U + s->pic.linesize[1];
225 uint8_t *V2 = V + s->pic.linesize[2];
227 for (j = 0; j < avctx->height >> 2; j++) {
228 for (i = 0; i < avctx->width >> 1; i += 2) {
230 if (val && val < table_size) {
231 val = AV_RL16(table + (val << 1));
232 uval = (val >> 3) & 0xF8;
233 vval = (val >> 8) & 0xF8;
234 U[i] = U[i+1] = U2[i] = U2[i+1] = uval | (uval >> 5);
235 V[i] = V[i+1] = V2[i] = V2[i+1] = vval | (vval >> 5);
238 U += s->pic.linesize[1] * 2;
239 V += s->pic.linesize[2] * 2;
240 U2 += s->pic.linesize[1] * 2;
241 V2 += s->pic.linesize[2] * 2;
243 if (avctx->height & 3) {
244 int lines = ((avctx->height + 1) >> 1) - (avctx->height >> 2) * 2;
246 memcpy(U, U - lines * s->pic.linesize[1], lines * s->pic.linesize[1]);
247 memcpy(V, V - lines * s->pic.linesize[2], lines * s->pic.linesize[2]);
254 static int xan_decode_frame_type0(AVCodecContext *avctx)
256 XanContext *s = avctx->priv_data;
257 uint8_t *ybuf, *prev_buf, *src = s->scratch_buffer;
258 unsigned chroma_off, corr_off;
263 chroma_off = bytestream2_get_le32(&s->gb);
264 corr_off = bytestream2_get_le32(&s->gb);
266 if ((ret = xan_decode_chroma(avctx, chroma_off)) != 0)
269 if (corr_off >= (s->gb.buffer_end - s->gb.buffer_start)) {
270 av_log(avctx, AV_LOG_WARNING, "Ignoring invalid correction block position\n");
273 bytestream2_seek(&s->gb, 12, SEEK_SET);
274 ret = xan_unpack_luma(s, src, s->buffer_size >> 1);
276 av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");
283 for (j = 1; j < avctx->width - 1; j += 2) {
284 cur = (last + *src++) & 0x1F;
285 ybuf[j] = last + cur;
286 ybuf[j+1] = cur << 1;
291 ybuf += avctx->width;
293 for (i = 1; i < avctx->height; i++) {
294 last = ((prev_buf[0] >> 1) + *src++) & 0x1F;
296 for (j = 1; j < avctx->width - 1; j += 2) {
297 cur = ((prev_buf[j + 1] >> 1) + *src++) & 0x1F;
298 ybuf[j] = last + cur;
299 ybuf[j+1] = cur << 1;
304 ybuf += avctx->width;
310 bytestream2_seek(&s->gb, 8 + corr_off, SEEK_SET);
311 dec_size = xan_unpack(s, s->scratch_buffer, s->buffer_size / 2);
314 for (i = 0; i < dec_size; i++)
315 s->y_buffer[i*2+1] = (s->y_buffer[i*2+1] + (s->scratch_buffer[i] << 1)) & 0x3F;
319 ybuf = s->pic.data[0];
320 for (j = 0; j < avctx->height; j++) {
321 for (i = 0; i < avctx->width; i++)
322 ybuf[i] = (src[i] << 2) | (src[i] >> 3);
324 ybuf += s->pic.linesize[0];
330 static int xan_decode_frame_type1(AVCodecContext *avctx)
332 XanContext *s = avctx->priv_data;
333 uint8_t *ybuf, *src = s->scratch_buffer;
338 if ((ret = xan_decode_chroma(avctx, bytestream2_get_le32(&s->gb))) != 0)
341 bytestream2_seek(&s->gb, 16, SEEK_SET);
342 ret = xan_unpack_luma(s, src,
343 s->buffer_size >> 1);
345 av_log(avctx, AV_LOG_ERROR, "Luma decoding failed\n");
350 for (i = 0; i < avctx->height; i++) {
351 last = (ybuf[0] + (*src++ << 1)) & 0x3F;
353 for (j = 1; j < avctx->width - 1; j += 2) {
354 cur = (ybuf[j + 1] + (*src++ << 1)) & 0x3F;
355 ybuf[j] = (last + cur) >> 1;
360 ybuf += avctx->width;
364 ybuf = s->pic.data[0];
365 for (j = 0; j < avctx->height; j++) {
366 for (i = 0; i < avctx->width; i++)
367 ybuf[i] = (src[i] << 2) | (src[i] >> 3);
369 ybuf += s->pic.linesize[0];
375 static int xan_decode_frame(AVCodecContext *avctx,
376 void *data, int *got_frame,
379 XanContext *s = avctx->priv_data;
383 if ((ret = ff_reget_buffer(avctx, &s->pic))) {
384 av_log(s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
388 bytestream2_init(&s->gb, avpkt->data, avpkt->size);
389 ftype = bytestream2_get_le32(&s->gb);
392 ret = xan_decode_frame_type0(avctx);
395 ret = xan_decode_frame_type1(avctx);
398 av_log(avctx, AV_LOG_ERROR, "Unknown frame type %d\n", ftype);
399 return AVERROR_INVALIDDATA;
404 if ((ret = av_frame_ref(data, &s->pic)) < 0)
412 static av_cold int xan_decode_end(AVCodecContext *avctx)
414 XanContext *s = avctx->priv_data;
416 av_frame_unref(&s->pic);
418 av_freep(&s->y_buffer);
419 av_freep(&s->scratch_buffer);
424 AVCodec ff_xan_wc4_decoder = {
426 .type = AVMEDIA_TYPE_VIDEO,
427 .id = AV_CODEC_ID_XAN_WC4,
428 .priv_data_size = sizeof(XanContext),
429 .init = xan_decode_init,
430 .close = xan_decode_end,
431 .decode = xan_decode_frame,
432 .capabilities = CODEC_CAP_DR1,
433 .long_name = NULL_IF_CONFIG_SMALL("Wing Commander IV / Xxan"),