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/*
* Targa (.tga) image encoder
* Copyright (c) 2007 Bobby Bingham
*
* 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
*
*/
#include "avcodec.h"
/**
* Count up to 127 consecutive pixels which are either all the same or
* all differ from the previous and next pixels.
* @param start Pointer to the first pixel
* @param len Maximum number of pixels
* @param bpp Bytes per pixel
* @param same 1 if searching for identical pixel values. 0 for differing
* @return Number of matching consecutive pixels found
*/
static int count_pixels(uint8_t *start, int len, int bpp, int same)
{
uint8_t *pos;
int count = 1;
for(pos = start + bpp; count < FFMIN(128, len); pos += bpp, count ++) {
if(same != !memcmp(pos-bpp, pos, bpp)) {
if(!same) {
/* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a single
* raw block of pixels. for larger bpp, RLE is as good or better */
if(bpp == 1 && count + 1 < FFMIN(128, len) && *pos != *(pos+1))
continue;
/* if RLE can encode the next block better than as a raw block,
* back up and leave _all_ the identical pixels for RLE */
count --;
}
break;
}
}
return count;
}
/**
* RLE compress the image, with maximum size of out_size
* @param outbuf Output buffer
* @param out_size Maximum output size
* @param pic Image to compress
* @param bpp Bytes per pixel
* @param w Image width
* @param h Image height
* @return Size of output in bytes, or -1 if larger than out_size
*/
static int targa_encode_rle(uint8_t *outbuf, int out_size, AVFrame *pic,
int bpp, int w, int h)
{
int count, x, y;
uint8_t *ptr, *line, *out;
out = outbuf;
line = pic->data[0];
for(y = 0; y < h; y ++) {
ptr = line;
for(x = 0; x < w; x += count) {
/* see if we can encode the next set of pixels with RLE */
if((count = count_pixels(ptr, w-x, bpp, 1)) > 1) {
if(out + bpp + 1 > outbuf + out_size) return -1;
*out++ = 0x80 | (count - 1);
memcpy(out, ptr, bpp);
out += bpp;
} else {
/* fall back on uncompressed */
count = count_pixels(ptr, w-x, bpp, 0);
*out++ = count - 1;
if(out + bpp*count > outbuf + out_size) return -1;
memcpy(out, ptr, bpp * count);
out += bpp * count;
}
ptr += count * bpp;
}
line += pic->linesize[0];
}
return out - outbuf;
}
static int targa_encode_normal(uint8_t *outbuf, AVFrame *pic, int bpp, int w, int h)
{
int i, n = bpp * w;
uint8_t *out = outbuf;
uint8_t *ptr = pic->data[0];
for(i=0; i < h; i++) {
memcpy(out, ptr, n);
out += n;
ptr += pic->linesize[0];
}
return out - outbuf;
}
static int targa_encode_frame(AVCodecContext *avctx,
unsigned char *outbuf,
int buf_size, void *data){
AVFrame *p = data;
int bpp, picsize, datasize;
uint8_t *out;
if(avctx->width > 0xffff || avctx->height > 0xffff) {
av_log(avctx, AV_LOG_ERROR, "image dimensions too large\n");
return -1;
}
picsize = avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height);
if(buf_size < picsize + 45) {
av_log(avctx, AV_LOG_ERROR, "encoded frame too large\n");
return -1;
}
p->pict_type= FF_I_TYPE;
p->key_frame= 1;
/* zero out the header and only set applicable fields */
memset(outbuf, 0, 11);
AV_WL16(outbuf+12, avctx->width);
AV_WL16(outbuf+14, avctx->height);
outbuf[17] = 0x20; /* origin is top-left. no alpha */
/* TODO: support alpha channel */
switch(avctx->pix_fmt) {
case PIX_FMT_GRAY8:
outbuf[2] = 3; /* uncompressed grayscale image */
outbuf[16] = 8; /* bpp */
break;
case PIX_FMT_RGB555:
outbuf[2] = 2; /* uncompresses true-color image */
outbuf[16] = 16; /* bpp */
break;
case PIX_FMT_BGR24:
outbuf[2] = 2; /* uncompressed true-color image */
outbuf[16] = 24; /* bpp */
break;
default:
return -1;
}
bpp = outbuf[16] >> 3;
out = outbuf + 18; /* skip past the header we just output */
/* try RLE compression */
datasize = targa_encode_rle(out, picsize, p, bpp, avctx->width, avctx->height);
/* if that worked well, mark the picture as RLE compressed */
if(datasize >= 0)
outbuf[2] |= 8;
/* if RLE didn't make it smaller, go back to no compression */
else datasize = targa_encode_normal(out, p, bpp, avctx->width, avctx->height);
out += datasize;
/* The standard recommends including this section, even if we don't use
* any of the features it affords. TODO: take advantage of the pixel
* aspect ratio and encoder ID fields available? */
memcpy(out, "\0\0\0\0\0\0\0\0TRUEVISION-XFILE.", 26);
return out + 26 - outbuf;
}
static int targa_encode_init(AVCodecContext *avctx)
{
return 0;
}
AVCodec targa_encoder = {
.name = "targa",
.type = CODEC_TYPE_VIDEO,
.id = CODEC_ID_TARGA,
.priv_data_size = 0,
.init = targa_encode_init,
.encode = targa_encode_frame,
.pix_fmts= (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_RGB555, PIX_FMT_GRAY8, -1},
};
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