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/*
* RL2 Video Decoder
* Copyright (C) 2008 Sascha Sommer (saschasommer@freenet.de)
*
* 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
* RL2 Video Decoder
* @author Sascha Sommer (saschasommer@freenet.de)
* @see http://wiki.multimedia.cx/index.php?title=RL2
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
#define EXTRADATA1_SIZE (6 + 256 * 3) ///< video base, clr count, palette
typedef struct Rl2Context {
AVCodecContext *avctx;
AVFrame frame;
unsigned short video_base; ///< initial drawing offset
unsigned int clr_count; ///< number of used colors (currently unused)
unsigned char* back_frame; ///< background frame
unsigned int palette[AVPALETTE_COUNT];
} Rl2Context;
/**
* Run Length Decode a single 320x200 frame
* @param s rl2 context
* @param in input buffer
* @param size input buffer size
* @param out ouput buffer
* @param stride stride of the output buffer
* @param video_base offset of the rle data inside the frame
*/
static void rl2_rle_decode(Rl2Context *s,const unsigned char* in,int size,
unsigned char* out,int stride,int video_base){
int base_x = video_base % s->avctx->width;
int base_y = video_base / s->avctx->width;
int stride_adj = stride - s->avctx->width;
int i;
const unsigned char* back_frame = s->back_frame;
const unsigned char* in_end = in + size;
const unsigned char* out_end = out + stride * s->avctx->height;
unsigned char* line_end = out + s->avctx->width;
/** copy start of the background frame */
for(i=0;i<=base_y;i++){
if(s->back_frame)
memcpy(out,back_frame,s->avctx->width);
out += stride;
back_frame += s->avctx->width;
}
back_frame += base_x - s->avctx->width;
line_end = out - stride_adj;
out += base_x - stride;
/** decode the variable part of the frame */
while(in < in_end){
unsigned char val = *in++;
int len = 1;
if(val >= 0x80){
if(in >= in_end)
break;
len = *in++;
if(!len)
break;
}
if(len >= out_end - out)
break;
if(s->back_frame)
val |= 0x80;
else
val &= ~0x80;
while(len--){
*out++ = (val == 0x80)? *back_frame:val;
back_frame++;
if(out == line_end){
out += stride_adj;
line_end += stride;
if(len >= out_end - out)
break;
}
}
}
/** copy the rest from the background frame */
if(s->back_frame){
while(out < out_end){
memcpy(out, back_frame, line_end - out);
back_frame += line_end - out;
out = line_end + stride_adj;
line_end += stride;
}
}
}
/**
* Initialize the decoder
* @param avctx decoder context
* @return 0 success, -1 on error
*/
static av_cold int rl2_decode_init(AVCodecContext *avctx)
{
Rl2Context *s = avctx->priv_data;
int back_size;
int i;
s->avctx = avctx;
avctx->pix_fmt = PIX_FMT_PAL8;
/** parse extra data */
if(!avctx->extradata || avctx->extradata_size < EXTRADATA1_SIZE){
av_log(avctx, AV_LOG_ERROR, "invalid extradata size\n");
return -1;
}
/** get frame_offset */
s->video_base = AV_RL16(&avctx->extradata[0]);
s->clr_count = AV_RL32(&avctx->extradata[2]);
if(s->video_base >= avctx->width * avctx->height){
av_log(avctx, AV_LOG_ERROR, "invalid video_base\n");
return -1;
}
/** initialize palette */
for(i=0;i<AVPALETTE_COUNT;i++)
s->palette[i] = AV_RB24(&avctx->extradata[6 + i * 3]);
/** decode background frame if present */
back_size = avctx->extradata_size - EXTRADATA1_SIZE;
if(back_size > 0){
unsigned char* back_frame = av_mallocz(avctx->width*avctx->height);
if(!back_frame)
return -1;
rl2_rle_decode(s,avctx->extradata + EXTRADATA1_SIZE,back_size,
back_frame,avctx->width,0);
s->back_frame = back_frame;
}
return 0;
}
static int rl2_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
Rl2Context *s = avctx->priv_data;
if(s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
/** get buffer */
s->frame.reference= 0;
if(avctx->get_buffer(avctx, &s->frame)) {
av_log(s->avctx, AV_LOG_ERROR, "get_buffer() failed\n");
return -1;
}
/** run length decode */
rl2_rle_decode(s,buf,buf_size,s->frame.data[0],s->frame.linesize[0],s->video_base);
/** make the palette available on the way out */
memcpy(s->frame.data[1], s->palette, AVPALETTE_SIZE);
*data_size = sizeof(AVFrame);
*(AVFrame*)data = s->frame;
/** report that the buffer was completely consumed */
return buf_size;
}
/**
* Uninit decoder
* @param avctx decoder context
* @return 0 success, -1 on error
*/
static av_cold int rl2_decode_end(AVCodecContext *avctx)
{
Rl2Context *s = avctx->priv_data;
if(s->frame.data[0])
avctx->release_buffer(avctx, &s->frame);
av_free(s->back_frame);
return 0;
}
AVCodec ff_rl2_decoder = {
"rl2",
AVMEDIA_TYPE_VIDEO,
CODEC_ID_RL2,
sizeof(Rl2Context),
rl2_decode_init,
NULL,
rl2_decode_end,
rl2_decode_frame,
CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("RL2 video"),
};
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