2 * Microsoft Video-1 Decoder
3 * Copyright (C) 2003 the ffmpeg project
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
23 * @file libavcodec/msvideo1.c
24 * Microsoft Video-1 Decoder by Mike Melanson (melanson@pcisys.net)
25 * For more information about the MS Video-1 format, visit:
26 * http://www.pcisys.net/~melanson/codecs/
28 * This decoder outputs either PAL8 or RGB555 data, depending on the
29 * whether a RGB palette was passed through palctrl;
30 * if it's present, then the data is PAL8; RGB555 otherwise.
38 #include "libavutil/intreadwrite.h"
41 #define PALETTE_COUNT 256
42 #define CHECK_STREAM_PTR(n) \
43 if ((stream_ptr + n) > s->size ) { \
44 av_log(s->avctx, AV_LOG_ERROR, " MS Video-1 warning: stream_ptr out of bounds (%d >= %d)\n", \
45 stream_ptr + n, s->size); \
49 typedef struct Msvideo1Context {
51 AVCodecContext *avctx;
54 const unsigned char *buf;
57 int mode_8bit; /* if it's not 8-bit, it's 16-bit */
61 static av_cold int msvideo1_decode_init(AVCodecContext *avctx)
63 Msvideo1Context *s = avctx->priv_data;
67 /* figure out the colorspace based on the presence of a palette */
68 if (s->avctx->palctrl) {
70 avctx->pix_fmt = PIX_FMT_PAL8;
73 avctx->pix_fmt = PIX_FMT_RGB555;
76 s->frame.data[0] = NULL;
81 static void msvideo1_decode_8bit(Msvideo1Context *s)
83 int block_ptr, pixel_ptr;
85 int pixel_x, pixel_y; /* pixel width and height iterators */
86 int block_x, block_y; /* block width and height iterators */
87 int blocks_wide, blocks_high; /* width and height in 4x4 blocks */
91 /* decoding parameters */
93 unsigned char byte_a, byte_b;
96 unsigned char colors[8];
97 unsigned char *pixels = s->frame.data[0];
98 int stride = s->frame.linesize[0];
102 blocks_wide = s->avctx->width / 4;
103 blocks_high = s->avctx->height / 4;
104 total_blocks = blocks_wide * blocks_high;
106 row_dec = stride + 4;
108 for (block_y = blocks_high; block_y > 0; block_y--) {
109 block_ptr = ((block_y * 4) - 1) * stride;
110 for (block_x = blocks_wide; block_x > 0; block_x--) {
111 /* check if this block should be skipped */
113 block_ptr += block_inc;
119 pixel_ptr = block_ptr;
121 /* get the next two bytes in the encoded data stream */
123 byte_a = s->buf[stream_ptr++];
124 byte_b = s->buf[stream_ptr++];
126 /* check if the decode is finished */
127 if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0))
129 else if ((byte_b & 0xFC) == 0x84) {
130 /* skip code, but don't count the current block */
131 skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
132 } else if (byte_b < 0x80) {
133 /* 2-color encoding */
134 flags = (byte_b << 8) | byte_a;
137 colors[0] = s->buf[stream_ptr++];
138 colors[1] = s->buf[stream_ptr++];
140 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
141 for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
142 pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
143 pixel_ptr -= row_dec;
145 } else if (byte_b >= 0x90) {
146 /* 8-color encoding */
147 flags = (byte_b << 8) | byte_a;
150 memcpy(colors, &s->buf[stream_ptr], 8);
153 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
154 for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
155 pixels[pixel_ptr++] =
156 colors[((pixel_y & 0x2) << 1) +
157 (pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
158 pixel_ptr -= row_dec;
161 /* 1-color encoding */
164 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
165 for (pixel_x = 0; pixel_x < 4; pixel_x++)
166 pixels[pixel_ptr++] = colors[0];
167 pixel_ptr -= row_dec;
171 block_ptr += block_inc;
176 /* make the palette available on the way out */
177 if (s->avctx->pix_fmt == PIX_FMT_PAL8) {
178 memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
179 if (s->avctx->palctrl->palette_changed) {
180 s->frame.palette_has_changed = 1;
181 s->avctx->palctrl->palette_changed = 0;
186 static void msvideo1_decode_16bit(Msvideo1Context *s)
188 int block_ptr, pixel_ptr;
190 int pixel_x, pixel_y; /* pixel width and height iterators */
191 int block_x, block_y; /* block width and height iterators */
192 int blocks_wide, blocks_high; /* width and height in 4x4 blocks */
196 /* decoding parameters */
198 unsigned char byte_a, byte_b;
199 unsigned short flags;
201 unsigned short colors[8];
202 unsigned short *pixels = (unsigned short *)s->frame.data[0];
203 int stride = s->frame.linesize[0] / 2;
207 blocks_wide = s->avctx->width / 4;
208 blocks_high = s->avctx->height / 4;
209 total_blocks = blocks_wide * blocks_high;
211 row_dec = stride + 4;
213 for (block_y = blocks_high; block_y > 0; block_y--) {
214 block_ptr = ((block_y * 4) - 1) * stride;
215 for (block_x = blocks_wide; block_x > 0; block_x--) {
216 /* check if this block should be skipped */
218 block_ptr += block_inc;
224 pixel_ptr = block_ptr;
226 /* get the next two bytes in the encoded data stream */
228 byte_a = s->buf[stream_ptr++];
229 byte_b = s->buf[stream_ptr++];
231 /* check if the decode is finished */
232 if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0)) {
234 } else if ((byte_b & 0xFC) == 0x84) {
235 /* skip code, but don't count the current block */
236 skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1;
237 } else if (byte_b < 0x80) {
238 /* 2- or 8-color encoding modes */
239 flags = (byte_b << 8) | byte_a;
242 colors[0] = AV_RL16(&s->buf[stream_ptr]);
244 colors[1] = AV_RL16(&s->buf[stream_ptr]);
247 if (colors[0] & 0x8000) {
248 /* 8-color encoding */
249 CHECK_STREAM_PTR(12);
250 colors[2] = AV_RL16(&s->buf[stream_ptr]);
252 colors[3] = AV_RL16(&s->buf[stream_ptr]);
254 colors[4] = AV_RL16(&s->buf[stream_ptr]);
256 colors[5] = AV_RL16(&s->buf[stream_ptr]);
258 colors[6] = AV_RL16(&s->buf[stream_ptr]);
260 colors[7] = AV_RL16(&s->buf[stream_ptr]);
263 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
264 for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
265 pixels[pixel_ptr++] =
266 colors[((pixel_y & 0x2) << 1) +
267 (pixel_x & 0x2) + ((flags & 0x1) ^ 1)];
268 pixel_ptr -= row_dec;
271 /* 2-color encoding */
272 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
273 for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1)
274 pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1];
275 pixel_ptr -= row_dec;
279 /* otherwise, it's a 1-color block */
280 colors[0] = (byte_b << 8) | byte_a;
282 for (pixel_y = 0; pixel_y < 4; pixel_y++) {
283 for (pixel_x = 0; pixel_x < 4; pixel_x++)
284 pixels[pixel_ptr++] = colors[0];
285 pixel_ptr -= row_dec;
289 block_ptr += block_inc;
295 static int msvideo1_decode_frame(AVCodecContext *avctx,
296 void *data, int *data_size,
297 const uint8_t *buf, int buf_size)
299 Msvideo1Context *s = avctx->priv_data;
304 s->frame.reference = 1;
305 s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
306 if (avctx->reget_buffer(avctx, &s->frame)) {
307 av_log(s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
312 msvideo1_decode_8bit(s);
314 msvideo1_decode_16bit(s);
316 *data_size = sizeof(AVFrame);
317 *(AVFrame*)data = s->frame;
319 /* report that the buffer was completely consumed */
323 static av_cold int msvideo1_decode_end(AVCodecContext *avctx)
325 Msvideo1Context *s = avctx->priv_data;
327 if (s->frame.data[0])
328 avctx->release_buffer(avctx, &s->frame);
333 AVCodec msvideo1_decoder = {
337 sizeof(Msvideo1Context),
338 msvideo1_decode_init,
341 msvideo1_decode_frame,
343 .long_name= NULL_IF_CONFIG_SMALL("Microsoft Video 1"),