mirror of
https://github.com/FFmpeg/FFmpeg.git
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294 lines
8.9 KiB
C
294 lines
8.9 KiB
C
/*
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* Discworld II BMV video decoder
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* Copyright (c) 2011 Konstantin Shishkov
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/common.h"
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#include "avcodec.h"
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#include "bytestream.h"
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#include "internal.h"
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enum BMVFlags{
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BMV_NOP = 0,
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BMV_END,
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BMV_DELTA,
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BMV_INTRA,
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BMV_SCROLL = 0x04,
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BMV_PALETTE = 0x08,
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BMV_COMMAND = 0x10,
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BMV_AUDIO = 0x20,
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BMV_EXT = 0x40,
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BMV_PRINT = 0x80
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};
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#define SCREEN_WIDE 640
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#define SCREEN_HIGH 429
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typedef struct BMVDecContext {
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AVCodecContext *avctx;
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uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
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uint32_t pal[256];
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const uint8_t *stream;
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} BMVDecContext;
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#define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
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static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
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{
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unsigned val, saved_val = 0;
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int tmplen = src_len;
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const uint8_t *src, *source_end = source + src_len;
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uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
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uint8_t *dst, *dst_end;
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int len, mask;
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int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
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int read_two_nibbles, flag;
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int advance_mode;
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int mode = 0;
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int i;
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if (src_len <= 0)
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return AVERROR_INVALIDDATA;
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if (forward) {
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src = source;
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dst = frame;
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dst_end = frame_end;
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} else {
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src = source + src_len - 1;
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dst = frame_end - 1;
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dst_end = frame - 1;
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}
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for (;;) {
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int shift = 0;
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flag = 0;
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/* The mode/len decoding is a bit strange:
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* values are coded as variable-length codes with nibble units,
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* code end is signalled by two top bits in the nibble being nonzero.
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* And since data is bytepacked and we read two nibbles at a time,
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* we may get a nibble belonging to the next code.
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* Hence this convoluted loop.
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*/
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if (!mode || (tmplen == 4)) {
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if (src < source || src >= source_end)
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return AVERROR_INVALIDDATA;
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val = *src;
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read_two_nibbles = 1;
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} else {
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val = saved_val;
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read_two_nibbles = 0;
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}
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if (!(val & 0xC)) {
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for (;;) {
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if (!read_two_nibbles) {
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if (src < source || src >= source_end)
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return AVERROR_INVALIDDATA;
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shift += 2;
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val |= *src << shift;
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if (*src & 0xC)
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break;
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}
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// two upper bits of the nibble is zero,
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// so shift top nibble value down into their place
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read_two_nibbles = 0;
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shift += 2;
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mask = (1 << shift) - 1;
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val = ((val >> 2) & ~mask) | (val & mask);
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NEXT_BYTE(src);
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if ((val & (0xC << shift))) {
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flag = 1;
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break;
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}
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}
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} else if (mode) {
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flag = tmplen != 4;
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}
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if (flag) {
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tmplen = 4;
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} else {
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saved_val = val >> (4 + shift);
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tmplen = 0;
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val &= (1 << (shift + 4)) - 1;
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NEXT_BYTE(src);
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}
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advance_mode = val & 1;
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len = (val >> 1) - 1;
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mode += 1 + advance_mode;
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if (mode >= 4)
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mode -= 3;
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if (len <= 0 || FFABS(dst_end - dst) < len)
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return AVERROR_INVALIDDATA;
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switch (mode) {
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case 1:
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if (forward) {
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if (dst - frame + SCREEN_WIDE < frame_off ||
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dst - frame + SCREEN_WIDE + frame_off < 0 ||
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frame_end - dst < frame_off + len ||
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frame_end - dst < len)
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return AVERROR_INVALIDDATA;
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for (i = 0; i < len; i++)
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dst[i] = dst[frame_off + i];
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dst += len;
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} else {
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dst -= len;
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if (dst - frame + SCREEN_WIDE < frame_off ||
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dst - frame + SCREEN_WIDE + frame_off < 0 ||
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frame_end - dst < frame_off + len ||
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frame_end - dst < len)
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return AVERROR_INVALIDDATA;
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for (i = len - 1; i >= 0; i--)
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dst[i] = dst[frame_off + i];
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}
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break;
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case 2:
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if (forward) {
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if (source + src_len - src < len)
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return AVERROR_INVALIDDATA;
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memcpy(dst, src, len);
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dst += len;
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src += len;
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} else {
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if (src - source < len)
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return AVERROR_INVALIDDATA;
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dst -= len;
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src -= len;
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memcpy(dst, src, len);
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}
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break;
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case 3:
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val = forward ? dst[-1] : dst[1];
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if (forward) {
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memset(dst, val, len);
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dst += len;
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} else {
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dst -= len;
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memset(dst, val, len);
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}
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break;
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default:
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break;
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}
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if (dst == dst_end)
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return 0;
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}
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return 0;
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}
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static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
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AVPacket *pkt)
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{
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BMVDecContext * const c = avctx->priv_data;
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AVFrame *frame = data;
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int type, scr_off;
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int i, ret;
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uint8_t *srcptr, *outptr;
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c->stream = pkt->data;
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type = bytestream_get_byte(&c->stream);
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if (type & BMV_AUDIO) {
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int blobs = bytestream_get_byte(&c->stream);
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if (pkt->size < blobs * 65 + 2) {
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av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
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return AVERROR_INVALIDDATA;
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}
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c->stream += blobs * 65;
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}
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if (type & BMV_COMMAND) {
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int command_size = (type & BMV_PRINT) ? 8 : 10;
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if (c->stream - pkt->data + command_size > pkt->size) {
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av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
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return AVERROR_INVALIDDATA;
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}
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c->stream += command_size;
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}
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if (type & BMV_PALETTE) {
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if (c->stream - pkt->data > pkt->size - 768) {
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av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
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return AVERROR_INVALIDDATA;
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}
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for (i = 0; i < 256; i++)
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c->pal[i] = bytestream_get_be24(&c->stream);
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}
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if (type & BMV_SCROLL) {
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if (c->stream - pkt->data > pkt->size - 2) {
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av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
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return AVERROR_INVALIDDATA;
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}
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scr_off = (int16_t)bytestream_get_le16(&c->stream);
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} else if ((type & BMV_INTRA) == BMV_INTRA) {
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scr_off = -640;
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} else {
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scr_off = 0;
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}
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if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
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av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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return ret;
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}
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if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
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av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
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return AVERROR_INVALIDDATA;
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}
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memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
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frame->palette_has_changed = type & BMV_PALETTE;
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outptr = frame->data[0];
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srcptr = c->frame;
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for (i = 0; i < avctx->height; i++) {
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memcpy(outptr, srcptr, avctx->width);
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srcptr += avctx->width;
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outptr += frame->linesize[0];
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}
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*got_frame = 1;
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/* always report that the buffer was completely consumed */
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return pkt->size;
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}
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static av_cold int decode_init(AVCodecContext *avctx)
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{
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BMVDecContext * const c = avctx->priv_data;
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c->avctx = avctx;
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avctx->pix_fmt = AV_PIX_FMT_PAL8;
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c->frame = c->frame_base + 640;
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return 0;
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}
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AVCodec ff_bmv_video_decoder = {
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.name = "bmv_video",
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.long_name = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
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.type = AVMEDIA_TYPE_VIDEO,
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.id = AV_CODEC_ID_BMV_VIDEO,
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.priv_data_size = sizeof(BMVDecContext),
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.init = decode_init,
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.decode = decode_frame,
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.capabilities = CODEC_CAP_DR1,
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};
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