/* * Wing Commander/Xan Video Decoder * Copyright (C) 2003 the ffmpeg project * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file xan.c * Xan video decoder for Wing Commander III computer game * by Mario Brito (mbrito@student.dei.uc.pt) * and Mike Melanson (melanson@pcisys.net) * * The xan_wc3 decoder outputs PAL8 data. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include "avcodec.h" typedef struct XanContext { AVCodecContext *avctx; AVFrame last_frame; AVFrame current_frame; unsigned char *buf; int size; /* scratch space */ unsigned char *buffer1; int buffer1_size; unsigned char *buffer2; int buffer2_size; int frame_size; } XanContext; static int xan_decode_init(AVCodecContext *avctx) { XanContext *s = avctx->priv_data; s->avctx = avctx; s->frame_size = 0; if ((avctx->codec->id == CODEC_ID_XAN_WC3) && (s->avctx->palctrl == NULL)) { av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n"); return -1; } avctx->pix_fmt = PIX_FMT_PAL8; if(avcodec_check_dimensions(avctx, avctx->width, avctx->height)) return -1; s->buffer1_size = avctx->width * avctx->height; s->buffer1 = av_malloc(s->buffer1_size); s->buffer2_size = avctx->width * avctx->height; s->buffer2 = av_malloc(s->buffer2_size); if (!s->buffer1 || !s->buffer2) return -1; return 0; } /* This function is used in lieu of memcpy(). This decoder cannot use * memcpy because the memory locations often overlap and * memcpy doesn't like that; it's not uncommon, for example, for * dest = src+1, to turn byte A into pattern AAAAAAAA. * This was originally repz movsb in Intel x86 ASM. */ static inline void bytecopy(unsigned char *dest, unsigned char *src, int count) { int i; for (i = 0; i < count; i++) dest[i] = src[i]; } static int xan_huffman_decode(unsigned char *dest, unsigned char *src, int dest_len) { unsigned char byte = *src++; unsigned char ival = byte + 0x16; unsigned char * ptr = src + byte*2; unsigned char val = ival; int counter = 0; unsigned char *dest_end = dest + dest_len; unsigned char bits = *ptr++; while ( val != 0x16 ) { if ( (1 << counter) & bits ) val = src[byte + val - 0x17]; else val = src[val - 0x17]; if ( val < 0x16 ) { if (dest + 1 > dest_end) return 0; *dest++ = val; val = ival; } if (counter++ == 7) { counter = 0; bits = *ptr++; } } return 0; } static void xan_unpack(unsigned char *dest, unsigned char *src, int dest_len) { unsigned char opcode; int size; int offset; int byte1, byte2, byte3; unsigned char *dest_end = dest + dest_len; for (;;) { opcode = *src++; if ( (opcode & 0x80) == 0 ) { offset = *src++; size = opcode & 3; if (dest + size > dest_end) return; bytecopy(dest, src, size); dest += size; src += size; size = ((opcode & 0x1c) >> 2) + 3; if (dest + size > dest_end) return; bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size); dest += size; } else if ( (opcode & 0x40) == 0 ) { byte1 = *src++; byte2 = *src++; size = byte1 >> 6; if (dest + size > dest_end) return; bytecopy (dest, src, size); dest += size; src += size; size = (opcode & 0x3f) + 4; if (dest + size > dest_end) return; bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size); dest += size; } else if ( (opcode & 0x20) == 0 ) { byte1 = *src++; byte2 = *src++; byte3 = *src++; size = opcode & 3; if (dest + size > dest_end) return; bytecopy (dest, src, size); dest += size; src += size; size = byte3 + 5 + ((opcode & 0xc) << 6); if (dest + size > dest_end) return; bytecopy (dest, dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2), size); dest += size; } else { size = ((opcode & 0x1f) << 2) + 4; if (size > 0x70) break; if (dest + size > dest_end) return; bytecopy (dest, src, size); dest += size; src += size; } } size = opcode & 3; bytecopy(dest, src, size); dest += size; src += size; } static inline void xan_wc3_output_pixel_run(XanContext *s, unsigned char *pixel_buffer, int x, int y, int pixel_count) { int stride; int line_inc; int index; int current_x; int width = s->avctx->width; unsigned char *palette_plane; palette_plane = s->current_frame.data[0]; stride = s->current_frame.linesize[0]; line_inc = stride - width; index = y * stride + x; current_x = x; while((pixel_count--) && (index < s->frame_size)) { /* don't do a memcpy() here; keyframes generally copy an entire * frame of data and the stride needs to be accounted for */ palette_plane[index++] = *pixel_buffer++; current_x++; if (current_x >= width) { index += line_inc; current_x = 0; } } } static inline void xan_wc3_copy_pixel_run(XanContext *s, int x, int y, int pixel_count, int motion_x, int motion_y) { int stride; int line_inc; int curframe_index, prevframe_index; int curframe_x, prevframe_x; int width = s->avctx->width; unsigned char *palette_plane, *prev_palette_plane; palette_plane = s->current_frame.data[0]; prev_palette_plane = s->last_frame.data[0]; stride = s->current_frame.linesize[0]; line_inc = stride - width; curframe_index = y * stride + x; curframe_x = x; prevframe_index = (y + motion_y) * stride + x + motion_x; prevframe_x = x + motion_x; while((pixel_count--) && (curframe_index < s->frame_size)) { palette_plane[curframe_index++] = prev_palette_plane[prevframe_index++]; curframe_x++; if (curframe_x >= width) { curframe_index += line_inc; curframe_x = 0; } prevframe_x++; if (prevframe_x >= width) { prevframe_index += line_inc; prevframe_x = 0; } } } static void xan_wc3_decode_frame(XanContext *s) { int width = s->avctx->width; int height = s->avctx->height; int total_pixels = width * height; unsigned char opcode; unsigned char flag = 0; int size = 0; int motion_x, motion_y; int x, y; unsigned char *opcode_buffer = s->buffer1; int opcode_buffer_size = s->buffer1_size; unsigned char *imagedata_buffer = s->buffer2; int imagedata_buffer_size = s->buffer2_size; /* pointers to segments inside the compressed chunk */ unsigned char *huffman_segment; unsigned char *size_segment; unsigned char *vector_segment; unsigned char *imagedata_segment; huffman_segment = s->buf + AV_RL16(&s->buf[0]); size_segment = s->buf + AV_RL16(&s->buf[2]); vector_segment = s->buf + AV_RL16(&s->buf[4]); imagedata_segment = s->buf + AV_RL16(&s->buf[6]); xan_huffman_decode(opcode_buffer, huffman_segment, opcode_buffer_size); if (imagedata_segment[0] == 2) xan_unpack(imagedata_buffer, &imagedata_segment[1], imagedata_buffer_size); else imagedata_buffer = &imagedata_segment[1]; /* use the decoded data segments to build the frame */ x = y = 0; while (total_pixels) { opcode = *opcode_buffer++; size = 0; switch (opcode) { case 0: flag ^= 1; continue; case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: size = opcode; break; case 12: case 13: case 14: case 15: case 16: case 17: case 18: size += (opcode - 10); break; case 9: case 19: size = *size_segment++; break; case 10: case 20: size = AV_RB16(&size_segment[0]); size_segment += 2; break; case 11: case 21: size = AV_RB24(size_segment); size_segment += 3; break; } if (opcode < 12) { flag ^= 1; if (flag) { /* run of (size) pixels is unchanged from last frame */ xan_wc3_copy_pixel_run(s, x, y, size, 0, 0); } else { /* output a run of pixels from imagedata_buffer */ xan_wc3_output_pixel_run(s, imagedata_buffer, x, y, size); imagedata_buffer += size; } } else { /* run-based motion compensation from last frame */ motion_x = (*vector_segment >> 4) & 0xF; motion_y = *vector_segment & 0xF; vector_segment++; /* sign extension */ if (motion_x & 0x8) motion_x |= 0xFFFFFFF0; if (motion_y & 0x8) motion_y |= 0xFFFFFFF0; /* copy a run of pixels from the previous frame */ xan_wc3_copy_pixel_run(s, x, y, size, motion_x, motion_y); flag = 0; } /* coordinate accounting */ total_pixels -= size; while (size) { if (x + size >= width) { y++; size -= (width - x); x = 0; } else { x += size; size = 0; } } } } static void xan_wc4_decode_frame(XanContext *s) { } static int xan_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size) { XanContext *s = avctx->priv_data; AVPaletteControl *palette_control = avctx->palctrl; if (avctx->get_buffer(avctx, &s->current_frame)) { av_log(s->avctx, AV_LOG_ERROR, " Xan Video: get_buffer() failed\n"); return -1; } s->current_frame.reference = 3; if (!s->frame_size) s->frame_size = s->current_frame.linesize[0] * s->avctx->height; palette_control->palette_changed = 0; memcpy(s->current_frame.data[1], palette_control->palette, AVPALETTE_SIZE); s->current_frame.palette_has_changed = 1; s->buf = buf; s->size = buf_size; if (avctx->codec->id == CODEC_ID_XAN_WC3) xan_wc3_decode_frame(s); else if (avctx->codec->id == CODEC_ID_XAN_WC4) xan_wc4_decode_frame(s); /* release the last frame if it is allocated */ if (s->last_frame.data[0]) avctx->release_buffer(avctx, &s->last_frame); /* shuffle frames */ s->last_frame = s->current_frame; *data_size = sizeof(AVFrame); *(AVFrame*)data = s->current_frame; /* always report that the buffer was completely consumed */ return buf_size; } static int xan_decode_end(AVCodecContext *avctx) { XanContext *s = avctx->priv_data; /* release the last frame */ if (s->last_frame.data[0]) avctx->release_buffer(avctx, &s->last_frame); av_free(s->buffer1); av_free(s->buffer2); return 0; } AVCodec xan_wc3_decoder = { "xan_wc3", CODEC_TYPE_VIDEO, CODEC_ID_XAN_WC3, sizeof(XanContext), xan_decode_init, NULL, xan_decode_end, xan_decode_frame, CODEC_CAP_DR1, }; /* AVCodec xan_wc4_decoder = { "xan_wc4", CODEC_TYPE_VIDEO, CODEC_ID_XAN_WC4, sizeof(XanContext), xan_decode_init, NULL, xan_decode_end, xan_decode_frame, CODEC_CAP_DR1, }; */