*/
#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 i, n, linesize;
- uint8_t *ptr, *out;
+ 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;
}
- if(buf_size < avpicture_get_size(avctx->pix_fmt, avctx->width, avctx->height) + 45) {
+ 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;
}
AV_WL16(outbuf+14, avctx->height);
outbuf[17] = 0x20; /* origin is top-left. no alpha */
- /* TODO: support alpha channel and other bit-depths. and RLE? */
+ /* TODO: support alpha channel */
switch(avctx->pix_fmt) {
case PIX_FMT_GRAY8:
outbuf[2] = 3; /* uncompressed grayscale image */
outbuf[16] = 8; /* bpp */
- n = avctx->width;
+ 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 */
- n = 3 * avctx->width;
break;
default:
return -1;
}
+ bpp = outbuf[16] >> 3;
out = outbuf + 18; /* skip past the header we just output */
- ptr = p->data[0];
- linesize = p->linesize[0];
- for(i=0; i < avctx->height; i++) {
- memcpy(out, ptr, n);
- out += n;
- ptr += linesize;
- }
+ /* 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
.priv_data_size = 0,
.init = targa_encode_init,
.encode = targa_encode_frame,
- .pix_fmts= (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_GRAY8, -1},
+ .pix_fmts= (enum PixelFormat[]){PIX_FMT_BGR24, PIX_FMT_RGB555, PIX_FMT_GRAY8, -1},
};
projects / ffmpeg / blobdiff