2 * Discworld II BMV video and audio decoder
3 * Copyright (c) 2011 Konstantin Shishkov
5 * This file is part of Libav.
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "bytestream.h"
24 #include "libavutil/avassert.h"
40 #define SCREEN_WIDE 640
41 #define SCREEN_HIGH 429
43 typedef struct BMVDecContext {
44 AVCodecContext *avctx;
47 uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
49 const uint8_t *stream;
52 #define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
54 static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
56 unsigned val, saved_val = 0;
58 const uint8_t *src, *source_end = source + src_len;
59 uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
60 uint8_t *dst, *dst_end;
62 int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
63 int read_two_nibbles, flag;
76 src = source + src_len - 1;
84 /* The mode/len decoding is a bit strange:
85 * values are coded as variable-length codes with nibble units,
86 * code end is signalled by two top bits in the nibble being nonzero.
87 * And since data is bytepacked and we read two nibbles at a time,
88 * we may get a nibble belonging to the next code.
89 * Hence this convoluted loop.
91 if (!mode || (tmplen == 4)) {
92 if (src < source || src >= source_end)
104 if (!read_two_nibbles) {
105 if (src < source || src >= source_end)
108 val |= *src << shift;
112 // two upper bits of the nibble is zero,
113 // so shift top nibble value down into their place
114 read_two_nibbles = 0;
116 mask = (1 << shift) - 1;
117 val = ((val >> 2) & ~mask) | (val & mask);
119 if ((val & (0xC << shift))) {
130 saved_val = val >> (4 + shift);
132 val &= (1 << (shift + 4)) - 1;
135 advance_mode = val & 1;
136 len = (val >> 1) - 1;
138 mode += 1 + advance_mode;
141 if (FFABS(dst_end - dst) < len)
146 if (dst - frame + SCREEN_WIDE < frame_off ||
147 dst - frame + SCREEN_WIDE + frame_off < 0 ||
148 frame_end - dst < frame_off + len ||
149 frame_end - dst < len)
151 for (i = 0; i < len; i++)
152 dst[i] = dst[frame_off + i];
156 if (dst - frame + SCREEN_WIDE < frame_off ||
157 dst - frame + SCREEN_WIDE + frame_off < 0 ||
158 frame_end - dst < frame_off + len ||
159 frame_end - dst < len)
161 for (i = len - 1; i >= 0; i--)
162 dst[i] = dst[frame_off + i];
167 if (source + src_len - src < len)
169 memcpy(dst, src, len);
173 if (src - source < len)
177 memcpy(dst, src, len);
181 val = forward ? dst[-1] : dst[1];
183 memset(dst, val, len);
187 memset(dst, val, len);
197 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *pkt)
199 BMVDecContext * const c = avctx->priv_data;
202 uint8_t *srcptr, *outptr;
204 c->stream = pkt->data;
205 type = bytestream_get_byte(&c->stream);
206 if (type & BMV_AUDIO) {
207 int blobs = bytestream_get_byte(&c->stream);
208 if (pkt->size < blobs * 65 + 2) {
209 av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
210 return AVERROR_INVALIDDATA;
212 c->stream += blobs * 65;
214 if (type & BMV_COMMAND) {
215 int command_size = (type & BMV_PRINT) ? 8 : 10;
216 if (c->stream - pkt->data + command_size > pkt->size) {
217 av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
218 return AVERROR_INVALIDDATA;
220 c->stream += command_size;
222 if (type & BMV_PALETTE) {
223 if (c->stream - pkt->data > pkt->size - 768) {
224 av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
225 return AVERROR_INVALIDDATA;
227 for (i = 0; i < 256; i++)
228 c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
230 if (type & BMV_SCROLL) {
231 if (c->stream - pkt->data > pkt->size - 2) {
232 av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
233 return AVERROR_INVALIDDATA;
235 scr_off = (int16_t)bytestream_get_le16(&c->stream);
236 } else if ((type & BMV_INTRA) == BMV_INTRA) {
242 if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
243 av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
244 return AVERROR_INVALIDDATA;
247 memcpy(c->pic.data[1], c->pal, AVPALETTE_SIZE);
248 c->pic.palette_has_changed = type & BMV_PALETTE;
250 outptr = c->pic.data[0];
253 for (i = 0; i < avctx->height; i++) {
254 memcpy(outptr, srcptr, avctx->width);
255 srcptr += avctx->width;
256 outptr += c->pic.linesize[0];
259 *data_size = sizeof(AVFrame);
260 *(AVFrame*)data = c->pic;
262 /* always report that the buffer was completely consumed */
266 static av_cold int decode_init(AVCodecContext *avctx)
268 BMVDecContext * const c = avctx->priv_data;
271 avctx->pix_fmt = AV_PIX_FMT_PAL8;
273 if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) {
274 av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height);
275 return AVERROR_INVALIDDATA;
278 c->pic.reference = 1;
279 if (avctx->get_buffer(avctx, &c->pic) < 0) {
280 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
284 c->frame = c->frame_base + 640;
289 static av_cold int decode_end(AVCodecContext *avctx)
291 BMVDecContext *c = avctx->priv_data;
294 avctx->release_buffer(avctx, &c->pic);
299 typedef struct BMVAudioDecContext {
301 } BMVAudioDecContext;
303 static const int bmv_aud_mults[16] = {
304 16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
307 static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
309 BMVAudioDecContext *c = avctx->priv_data;
311 if (avctx->channels != 2) {
312 av_log(avctx, AV_LOG_INFO, "invalid number of channels\n");
313 return AVERROR(EINVAL);
316 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
318 avcodec_get_frame_defaults(&c->frame);
319 avctx->coded_frame = &c->frame;
324 static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
325 int *got_frame_ptr, AVPacket *avpkt)
327 BMVAudioDecContext *c = avctx->priv_data;
328 const uint8_t *buf = avpkt->data;
329 int buf_size = avpkt->size;
330 int blocks = 0, total_blocks, i;
332 int16_t *output_samples;
335 total_blocks = *buf++;
336 if (buf_size < total_blocks * 65 + 1) {
337 av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
338 total_blocks * 65 + 1, buf_size);
339 return AVERROR_INVALIDDATA;
342 /* get output buffer */
343 c->frame.nb_samples = total_blocks * 32;
344 if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) {
345 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
348 output_samples = (int16_t *)c->frame.data[0];
350 for (blocks = 0; blocks < total_blocks; blocks++) {
351 uint8_t code = *buf++;
352 code = (code >> 1) | (code << 7);
353 scale[0] = bmv_aud_mults[code & 0xF];
354 scale[1] = bmv_aud_mults[code >> 4];
355 for (i = 0; i < 32; i++) {
356 *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
357 *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
362 *(AVFrame *)data = c->frame;
367 AVCodec ff_bmv_video_decoder = {
369 .type = AVMEDIA_TYPE_VIDEO,
370 .id = AV_CODEC_ID_BMV_VIDEO,
371 .priv_data_size = sizeof(BMVDecContext),
374 .decode = decode_frame,
375 .capabilities = CODEC_CAP_DR1,
376 .long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
379 AVCodec ff_bmv_audio_decoder = {
381 .type = AVMEDIA_TYPE_AUDIO,
382 .id = AV_CODEC_ID_BMV_AUDIO,
383 .priv_data_size = sizeof(BMVAudioDecContext),
384 .init = bmv_aud_decode_init,
385 .decode = bmv_aud_decode_frame,
386 .capabilities = CODEC_CAP_DR1,
387 .long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),