/* * Wing Commander/Xan Video Decoder * Copyright (C) 2003 the ffmpeg project * * This file is part of Libav. * * Libav 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. * * Libav 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 Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * 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 "libavutil/intreadwrite.h" #include "libavutil/mem.h" #include "avcodec.h" #include "bytestream.h" #define BITSTREAM_READER_LE #include "get_bits.h" #include "internal.h" #define RUNTIME_GAMMA 0 #define VGA__TAG MKTAG('V', 'G', 'A', ' ') #define PALT_TAG MKTAG('P', 'A', 'L', 'T') #define SHOT_TAG MKTAG('S', 'H', 'O', 'T') #define PALETTE_COUNT 256 #define PALETTE_SIZE (PALETTE_COUNT * 3) #define PALETTES_MAX 256 typedef struct XanContext { AVCodecContext *avctx; AVFrame *last_frame; const unsigned char *buf; int size; /* scratch space */ unsigned char *buffer1; int buffer1_size; unsigned char *buffer2; int buffer2_size; unsigned *palettes; int palettes_count; int cur_palette; int frame_size; } XanContext; static av_cold int xan_decode_end(AVCodecContext *avctx) { XanContext *s = avctx->priv_data; av_frame_free(&s->last_frame); av_freep(&s->buffer1); av_freep(&s->buffer2); av_freep(&s->palettes); return 0; } static av_cold int xan_decode_init(AVCodecContext *avctx) { XanContext *s = avctx->priv_data; s->avctx = avctx; s->frame_size = 0; avctx->pix_fmt = AV_PIX_FMT_PAL8; s->buffer1_size = avctx->width * avctx->height; s->buffer1 = av_malloc(s->buffer1_size); if (!s->buffer1) return AVERROR(ENOMEM); s->buffer2_size = avctx->width * avctx->height; s->buffer2 = av_malloc(s->buffer2_size + 130); if (!s->buffer2) { av_freep(&s->buffer1); return AVERROR(ENOMEM); } s->last_frame = av_frame_alloc(); if (!s->last_frame) { xan_decode_end(avctx); return AVERROR(ENOMEM); } return 0; } static int xan_huffman_decode(unsigned char *dest, int dest_len, const unsigned char *src, int src_len) { unsigned char byte = *src++; unsigned char ival = byte + 0x16; const unsigned char * ptr = src + byte*2; int ptr_len = src_len - 1 - byte*2; unsigned char val = ival; unsigned char *dest_end = dest + dest_len; unsigned char *dest_start = dest; GetBitContext gb; if (ptr_len < 0) return AVERROR_INVALIDDATA; init_get_bits(&gb, ptr, ptr_len * 8); while (val != 0x16) { unsigned idx = val - 0x17 + get_bits1(&gb) * byte; if (idx >= 2 * byte) return AVERROR_INVALIDDATA; val = src[idx]; if (val < 0x16) { if (dest >= dest_end) return dest_len; *dest++ = val; val = ival; } } return dest - dest_start; } /** * unpack simple compression * * @param dest destination buffer of dest_len, must be padded with at least 130 bytes */ static void xan_unpack(unsigned char *dest, int dest_len, const unsigned char *src, int src_len) { unsigned char opcode; int size; unsigned char *dest_org = dest; unsigned char *dest_end = dest + dest_len; GetByteContext ctx; bytestream2_init(&ctx, src, src_len); while (dest < dest_end && bytestream2_get_bytes_left(&ctx)) { opcode = bytestream2_get_byte(&ctx); if (opcode < 0xe0) { int size2, back; if ((opcode & 0x80) == 0) { size = opcode & 3; back = ((opcode & 0x60) << 3) + bytestream2_get_byte(&ctx) + 1; size2 = ((opcode & 0x1c) >> 2) + 3; } else if ((opcode & 0x40) == 0) { size = bytestream2_peek_byte(&ctx) >> 6; back = (bytestream2_get_be16(&ctx) & 0x3fff) + 1; size2 = (opcode & 0x3f) + 4; } else { size = opcode & 3; back = ((opcode & 0x10) << 12) + bytestream2_get_be16(&ctx) + 1; size2 = ((opcode & 0x0c) << 6) + bytestream2_get_byte(&ctx) + 5; } if (dest_end - dest < size + size2 || dest + size - dest_org < back || bytestream2_get_bytes_left(&ctx) < size) return; bytestream2_get_buffer(&ctx, dest, size); dest += size; av_memcpy_backptr(dest, back, size2); dest += size2; } else { int finish = opcode >= 0xfc; size = finish ? opcode & 3 : ((opcode & 0x1f) << 2) + 4; if (dest_end - dest < size || bytestream2_get_bytes_left(&ctx) < size) return; bytestream2_get_buffer(&ctx, dest, size); dest += size; if (finish) return; } } } static inline void xan_wc3_output_pixel_run(XanContext *s, AVFrame *frame, const 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 = frame->data[0]; stride = frame->linesize[0]; line_inc = stride - width; index = y * stride + x; current_x = x; while (pixel_count && index < s->frame_size) { int count = FFMIN(pixel_count, width - current_x); memcpy(palette_plane + index, pixel_buffer, count); pixel_count -= count; index += count; pixel_buffer += count; current_x += count; if (current_x >= width) { index += line_inc; current_x = 0; } } } static inline void xan_wc3_copy_pixel_run(XanContext *s, AVFrame *frame, 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; if (y + motion_y < 0 || y + motion_y >= s->avctx->height || x + motion_x < 0 || x + motion_x >= s->avctx->width) return; palette_plane = frame->data[0]; prev_palette_plane = s->last_frame->data[0]; if (!prev_palette_plane) prev_palette_plane = palette_plane; stride = 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 && prevframe_index < s->frame_size) { int count = FFMIN3(pixel_count, width - curframe_x, width - prevframe_x); memcpy(palette_plane + curframe_index, prev_palette_plane + prevframe_index, count); pixel_count -= count; curframe_index += count; prevframe_index += count; curframe_x += count; prevframe_x += count; if (curframe_x >= width) { curframe_index += line_inc; curframe_x = 0; } if (prevframe_x >= width) { prevframe_index += line_inc; prevframe_x = 0; } } } static int xan_wc3_decode_frame(XanContext *s, AVFrame *frame) { 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, ret; unsigned char *opcode_buffer = s->buffer1; unsigned char *opcode_buffer_end = s->buffer1 + s->buffer1_size; int opcode_buffer_size = s->buffer1_size; const unsigned char *imagedata_buffer = s->buffer2; /* pointers to segments inside the compressed chunk */ const unsigned char *huffman_segment; GetByteContext size_segment; GetByteContext vector_segment; const unsigned char *imagedata_segment; int huffman_offset, size_offset, vector_offset, imagedata_offset, imagedata_size; if (s->size < 8) return AVERROR_INVALIDDATA; huffman_offset = AV_RL16(&s->buf[0]); size_offset = AV_RL16(&s->buf[2]); vector_offset = AV_RL16(&s->buf[4]); imagedata_offset = AV_RL16(&s->buf[6]); if (huffman_offset >= s->size || size_offset >= s->size || vector_offset >= s->size || imagedata_offset >= s->size) return AVERROR_INVALIDDATA; huffman_segment = s->buf + huffman_offset; bytestream2_init(&size_segment, s->buf + size_offset, s->size - size_offset); bytestream2_init(&vector_segment, s->buf + vector_offset, s->size - vector_offset); imagedata_segment = s->buf + imagedata_offset; if ((ret = xan_huffman_decode(opcode_buffer, opcode_buffer_size, huffman_segment, s->size - huffman_offset)) < 0) return AVERROR_INVALIDDATA; opcode_buffer_end = opcode_buffer + ret; if (imagedata_segment[0] == 2) { xan_unpack(s->buffer2, s->buffer2_size, &imagedata_segment[1], s->size - imagedata_offset - 1); imagedata_size = s->buffer2_size; } else { imagedata_size = s->size - imagedata_offset - 1; imagedata_buffer = &imagedata_segment[1]; } /* use the decoded data segments to build the frame */ x = y = 0; while (total_pixels && opcode_buffer < opcode_buffer_end) { 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 = bytestream2_get_byte(&size_segment); break; case 10: case 20: size = bytestream2_get_be16(&size_segment); break; case 11: case 21: size = bytestream2_get_be24(&size_segment); break; } if (size > total_pixels) break; if (opcode < 12) { flag ^= 1; if (flag) { /* run of (size) pixels is unchanged from last frame */ xan_wc3_copy_pixel_run(s, frame, x, y, size, 0, 0); } else { /* output a run of pixels from imagedata_buffer */ if (imagedata_size < size) break; xan_wc3_output_pixel_run(s, frame, imagedata_buffer, x, y, size); imagedata_buffer += size; imagedata_size -= size; } } else { /* run-based motion compensation from last frame */ uint8_t vector = bytestream2_get_byte(&vector_segment); motion_x = sign_extend(vector >> 4, 4); motion_y = sign_extend(vector & 0xF, 4); /* copy a run of pixels from the previous frame */ xan_wc3_copy_pixel_run(s, frame, x, y, size, motion_x, motion_y); flag = 0; } /* coordinate accounting */ total_pixels -= size; y += (x + size) / width; x = (x + size) % width; } return 0; } #if RUNTIME_GAMMA static inline unsigned mul(unsigned a, unsigned b) { return (a * b) >> 16; } static inline unsigned pow4(unsigned a) { unsigned square = mul(a, a); return mul(square, square); } static inline unsigned pow5(unsigned a) { return mul(pow4(a), a); } static uint8_t gamma_corr(uint8_t in) { unsigned lo, hi = 0xff40, target; int i = 15; in = (in << 2) | (in >> 6); /* equivalent float code: if (in >= 252) return 253; return round(pow(in / 256.0, 0.8) * 256); */ lo = target = in << 8; do { unsigned mid = (lo + hi) >> 1; unsigned pow = pow5(mid); if (pow > target) hi = mid; else lo = mid; } while (--i); return (pow4((lo + hi) >> 1) + 0x80) >> 8; } #else /** * This is a gamma correction that xan3 applies to all palette entries. * * There is a peculiarity, namely that the values are clamped to 253 - * it seems likely that this table was calculated by a buggy fixed-point * implementation, the one above under RUNTIME_GAMMA behaves like this for * example. * The exponent value of 0.8 can be explained by this as well, since 0.8 = 4/5 * and thus pow(x, 0.8) is still easy to calculate. * Also, the input values are first rotated to the left by 2. */ static const uint8_t gamma_lookup[256] = { 0x00, 0x09, 0x10, 0x16, 0x1C, 0x21, 0x27, 0x2C, 0x31, 0x35, 0x3A, 0x3F, 0x43, 0x48, 0x4C, 0x50, 0x54, 0x59, 0x5D, 0x61, 0x65, 0x69, 0x6D, 0x71, 0x75, 0x79, 0x7D, 0x80, 0x84, 0x88, 0x8C, 0x8F, 0x93, 0x97, 0x9A, 0x9E, 0xA2, 0xA5, 0xA9, 0xAC, 0xB0, 0xB3, 0xB7, 0xBA, 0xBE, 0xC1, 0xC5, 0xC8, 0xCB, 0xCF, 0xD2, 0xD5, 0xD9, 0xDC, 0xDF, 0xE3, 0xE6, 0xE9, 0xED, 0xF0, 0xF3, 0xF6, 0xFA, 0xFD, 0x03, 0x0B, 0x12, 0x18, 0x1D, 0x23, 0x28, 0x2D, 0x32, 0x36, 0x3B, 0x40, 0x44, 0x49, 0x4D, 0x51, 0x56, 0x5A, 0x5E, 0x62, 0x66, 0x6A, 0x6E, 0x72, 0x76, 0x7A, 0x7D, 0x81, 0x85, 0x89, 0x8D, 0x90, 0x94, 0x98, 0x9B, 0x9F, 0xA2, 0xA6, 0xAA, 0xAD, 0xB1, 0xB4, 0xB8, 0xBB, 0xBF, 0xC2, 0xC5, 0xC9, 0xCC, 0xD0, 0xD3, 0xD6, 0xDA, 0xDD, 0xE0, 0xE4, 0xE7, 0xEA, 0xED, 0xF1, 0xF4, 0xF7, 0xFA, 0xFD, 0x05, 0x0D, 0x13, 0x19, 0x1F, 0x24, 0x29, 0x2E, 0x33, 0x38, 0x3C, 0x41, 0x45, 0x4A, 0x4E, 0x52, 0x57, 0x5B, 0x5F, 0x63, 0x67, 0x6B, 0x6F, 0x73, 0x77, 0x7B, 0x7E, 0x82, 0x86, 0x8A, 0x8D, 0x91, 0x95, 0x99, 0x9C, 0xA0, 0xA3, 0xA7, 0xAA, 0xAE, 0xB2, 0xB5, 0xB9, 0xBC, 0xBF, 0xC3, 0xC6, 0xCA, 0xCD, 0xD0, 0xD4, 0xD7, 0xDA, 0xDE, 0xE1, 0xE4, 0xE8, 0xEB, 0xEE, 0xF1, 0xF5, 0xF8, 0xFB, 0xFD, 0x07, 0x0E, 0x15, 0x1A, 0x20, 0x25, 0x2A, 0x2F, 0x34, 0x39, 0x3D, 0x42, 0x46, 0x4B, 0x4F, 0x53, 0x58, 0x5C, 0x60, 0x64, 0x68, 0x6C, 0x70, 0x74, 0x78, 0x7C, 0x7F, 0x83, 0x87, 0x8B, 0x8E, 0x92, 0x96, 0x99, 0x9D, 0xA1, 0xA4, 0xA8, 0xAB, 0xAF, 0xB2, 0xB6, 0xB9, 0xBD, 0xC0, 0xC4, 0xC7, 0xCB, 0xCE, 0xD1, 0xD5, 0xD8, 0xDB, 0xDF, 0xE2, 0xE5, 0xE9, 0xEC, 0xEF, 0xF2, 0xF6, 0xF9, 0xFC, 0xFD }; #endif static int xan_decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt) { AVFrame *frame = data; const uint8_t *buf = avpkt->data; int ret, buf_size = avpkt->size; XanContext *s = avctx->priv_data; GetByteContext ctx; int tag = 0; bytestream2_init(&ctx, buf, buf_size); while (bytestream2_get_bytes_left(&ctx) > 8 && tag != VGA__TAG) { unsigned *tmpptr; uint32_t new_pal; int size; int i; tag = bytestream2_get_le32(&ctx); size = bytestream2_get_be32(&ctx); size = FFMIN(size, bytestream2_get_bytes_left(&ctx)); switch (tag) { case PALT_TAG: if (size < PALETTE_SIZE) return AVERROR_INVALIDDATA; if (s->palettes_count >= PALETTES_MAX) return AVERROR_INVALIDDATA; tmpptr = av_realloc(s->palettes, (s->palettes_count + 1) * AVPALETTE_SIZE); if (!tmpptr) return AVERROR(ENOMEM); s->palettes = tmpptr; tmpptr += s->palettes_count * AVPALETTE_COUNT; for (i = 0; i < PALETTE_COUNT; i++) { #if RUNTIME_GAMMA int r = gamma_corr(bytestream2_get_byteu(&ctx)); int g = gamma_corr(bytestream2_get_byteu(&ctx)); int b = gamma_corr(bytestream2_get_byteu(&ctx)); #else int r = gamma_lookup[bytestream2_get_byteu(&ctx)]; int g = gamma_lookup[bytestream2_get_byteu(&ctx)]; int b = gamma_lookup[bytestream2_get_byteu(&ctx)]; #endif *tmpptr++ = (r << 16) | (g << 8) | b; } s->palettes_count++; break; case SHOT_TAG: if (size < 4) return AVERROR_INVALIDDATA; new_pal = bytestream2_get_le32(&ctx); if (new_pal < s->palettes_count) { s->cur_palette = new_pal; } else av_log(avctx, AV_LOG_ERROR, "Invalid palette selected\n"); break; case VGA__TAG: break; default: bytestream2_skip(&ctx, size); break; } } buf_size = bytestream2_get_bytes_left(&ctx); if (s->palettes_count <= 0) { av_log(s->avctx, AV_LOG_ERROR, "No palette found\n"); return AVERROR_INVALIDDATA; } if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF))) { av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n"); return ret; } if (!s->frame_size) s->frame_size = frame->linesize[0] * s->avctx->height; memcpy(frame->data[1], s->palettes + s->cur_palette * AVPALETTE_COUNT, AVPALETTE_SIZE); s->buf = ctx.buffer; s->size = buf_size; if (xan_wc3_decode_frame(s, frame) < 0) return AVERROR_INVALIDDATA; av_frame_unref(s->last_frame); if ((ret = av_frame_ref(s->last_frame, frame)) < 0) return ret; *got_frame = 1; /* always report that the buffer was completely consumed */ return buf_size; } AVCodec ff_xan_wc3_decoder = { .name = "xan_wc3", .long_name = NULL_IF_CONFIG_SMALL("Wing Commander III / Xan"), .type = AVMEDIA_TYPE_VIDEO, .id = AV_CODEC_ID_XAN_WC3, .priv_data_size = sizeof(XanContext), .init = xan_decode_init, .close = xan_decode_end, .decode = xan_decode_frame, .capabilities = CODEC_CAP_DR1, };