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ffmpeg/libavcodec/msrle.c
Michael Niedermayer 934982c4ac avoid buf_size == 0 checks in every decoder 
Originally committed as revision 3872 to svn://svn.ffmpeg.org/ffmpeg/trunk
2005-01-23 18:09:06 +00:00

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9.7 KiB
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/*
* Micrsoft RLE Video Decoder
* Copyright (C) 2003 the ffmpeg project
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file msrle.c
* MS RLE Video Decoder by Mike Melanson (melanson@pcisys.net)
* For more information about the MS RLE format, visit:
* http://www.pcisys.net/~melanson/codecs/
*
* The MS RLE decoder outputs PAL8 colorspace data.
*
* Note that this decoder expects the palette colors from the end of the
* BITMAPINFO header passed through palctrl.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "common.h"
#include "avcodec.h"
#include "dsputil.h"
typedef struct MsrleContext {
AVCodecContext *avctx;
AVFrame frame;
unsigned char *buf;
int size;
} MsrleContext;
#define FETCH_NEXT_STREAM_BYTE() \
if (stream_ptr >= s->size) \
{ \
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (1)\n"); \
return; \
} \
stream_byte = s->buf[stream_ptr++];
static void msrle_decode_pal4(MsrleContext *s)
{
int stream_ptr = 0;
unsigned char rle_code;
unsigned char extra_byte, odd_pixel;
unsigned char stream_byte;
int pixel_ptr = 0;
int row_dec = s->frame.linesize[0];
int row_ptr = (s->avctx->height - 1) * row_dec;
int frame_size = row_dec * s->avctx->height;
int i;
/* make the palette available */
memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
if (s->avctx->palctrl->palette_changed) {
s->frame.palette_has_changed = 1;
s->avctx->palctrl->palette_changed = 0;
}
while (row_ptr >= 0) {
FETCH_NEXT_STREAM_BYTE();
rle_code = stream_byte;
if (rle_code == 0) {
/* fetch the next byte to see how to handle escape code */
FETCH_NEXT_STREAM_BYTE();
if (stream_byte == 0) {
/* line is done, goto the next one */
row_ptr -= row_dec;
pixel_ptr = 0;
} else if (stream_byte == 1) {
/* decode is done */
return;
} else if (stream_byte == 2) {
/* reposition frame decode coordinates */
FETCH_NEXT_STREAM_BYTE();
pixel_ptr += stream_byte;
FETCH_NEXT_STREAM_BYTE();
row_ptr -= stream_byte * row_dec;
} else {
// copy pixels from encoded stream
odd_pixel = stream_byte & 1;
rle_code = (stream_byte + 1) / 2;
extra_byte = rle_code & 0x01;
if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
(row_ptr < 0)) {
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
return;
}
for (i = 0; i < rle_code; i++) {
if (pixel_ptr >= s->avctx->width)
break;
FETCH_NEXT_STREAM_BYTE();
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
pixel_ptr++;
if (i + 1 == rle_code && odd_pixel)
break;
if (pixel_ptr >= s->avctx->width)
break;
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
pixel_ptr++;
}
// if the RLE code is odd, skip a byte in the stream
if (extra_byte)
stream_ptr++;
}
} else {
// decode a run of data
if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
(row_ptr < 0)) {
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
return;
}
FETCH_NEXT_STREAM_BYTE();
for (i = 0; i < rle_code; i++) {
if (pixel_ptr >= s->avctx->width)
break;
if ((i & 1) == 0)
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte >> 4;
else
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;
pixel_ptr++;
}
}
}
/* one last sanity check on the way out */
if (stream_ptr < s->size)
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: ended frame decode with bytes left over (%d < %d)\n",
stream_ptr, s->size);
}
static void msrle_decode_pal8(MsrleContext *s)
{
int stream_ptr = 0;
unsigned char rle_code;
unsigned char extra_byte;
unsigned char stream_byte;
int pixel_ptr = 0;
int row_dec = s->frame.linesize[0];
int row_ptr = (s->avctx->height - 1) * row_dec;
int frame_size = row_dec * s->avctx->height;
/* make the palette available */
memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);
if (s->avctx->palctrl->palette_changed) {
s->frame.palette_has_changed = 1;
s->avctx->palctrl->palette_changed = 0;
}
while (row_ptr >= 0) {
FETCH_NEXT_STREAM_BYTE();
rle_code = stream_byte;
if (rle_code == 0) {
/* fetch the next byte to see how to handle escape code */
FETCH_NEXT_STREAM_BYTE();
if (stream_byte == 0) {
/* line is done, goto the next one */
row_ptr -= row_dec;
pixel_ptr = 0;
} else if (stream_byte == 1) {
/* decode is done */
return;
} else if (stream_byte == 2) {
/* reposition frame decode coordinates */
FETCH_NEXT_STREAM_BYTE();
pixel_ptr += stream_byte;
FETCH_NEXT_STREAM_BYTE();
row_ptr -= stream_byte * row_dec;
} else {
/* copy pixels from encoded stream */
if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
(row_ptr < 0)) {
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");
return;
}
rle_code = stream_byte;
extra_byte = stream_byte & 0x01;
if (stream_ptr + rle_code + extra_byte > s->size) {
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (2)\n");
return;
}
while (rle_code--) {
FETCH_NEXT_STREAM_BYTE();
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
pixel_ptr++;
}
/* if the RLE code is odd, skip a byte in the stream */
if (extra_byte)
stream_ptr++;
}
} else {
/* decode a run of data */
if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||
(row_ptr < 0)) {
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (2)\n");
return;
}
FETCH_NEXT_STREAM_BYTE();
while(rle_code--) {
s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;
pixel_ptr++;
}
}
}
/* one last sanity check on the way out */
if (stream_ptr < s->size)
av_log(s->avctx, AV_LOG_ERROR, " MS RLE: ended frame decode with bytes left over (%d < %d)\n",
stream_ptr, s->size);
}
static int msrle_decode_init(AVCodecContext *avctx)
{
MsrleContext *s = (MsrleContext *)avctx->priv_data;
s->avctx = avctx;
avctx->pix_fmt = PIX_FMT_PAL8;
avctx->has_b_frames = 0;
s->frame.data[0] = NULL;
return 0;
}
static int msrle_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
MsrleContext *s = (MsrleContext *)avctx->priv_data;
s->buf = buf;
s->size = buf_size;
s->frame.reference = 1;
s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
if (avctx->reget_buffer(avctx, &s->frame)) {
av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
return -1;
}
switch (avctx->bits_per_sample) {
case 8:
msrle_decode_pal8(s);
break;
case 4:
msrle_decode_pal4(s);
break;
default:
av_log(avctx, AV_LOG_ERROR, "Don't know how to decode depth %u.\n",
avctx->bits_per_sample);
}
*data_size = sizeof(AVFrame);
*(AVFrame*)data = s->frame;
/* report that the buffer was completely consumed */
return buf_size;
}
static int msrle_decode_end(AVCodecContext *avctx)
{
MsrleContext *s = (MsrleContext *)avctx->priv_data;
/* release the last frame */
if (s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
return 0;
}
AVCodec msrle_decoder = {
"msrle",
CODEC_TYPE_VIDEO,
CODEC_ID_MSRLE,
sizeof(MsrleContext),
msrle_decode_init,
NULL,
msrle_decode_end,
msrle_decode_frame,
CODEC_CAP_DR1,
};
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