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ffmpeg/libavcodec/xan.c

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/*
* 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 = AV_CODEC_CAP_DR1,
};
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