Commit 74419fcf authored by Stefano Sabatini's avatar Stefano Sabatini

examples: add scaling_video example

This example should be useful to show the basic functionality of the
libswscale API.

More advanced features (scaling options etc., colorspace tweaking) may be
added later.
parent 316afee7
......@@ -16,6 +16,7 @@ EXAMPLES= decoding_encoding \
filtering_audio \
metadata \
muxing \
scaling_video \
OBJS=$(addsuffix .o,$(EXAMPLES))
......@@ -28,7 +29,7 @@ muxing: LDLIBS += -lm
all: $(OBJS) $(EXAMPLES)
clean-test:
$(RM) -f test*.pgm test.h264 test.mp2 test.sw test.mpg
$(RM) -f test*.pgm test.h264 test.mp2 test.sw test.mpg outscale*.pgm
clean: clean-test
$(RM) -f $(EXAMPLES) $(OBJS)
/*
* Copyright (c) 2012 Stefano Sabatini
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <libavutil/imgutils.h>
#include <libavutil/parseutils.h>
#include <libswscale/swscale.h>
static void fill_yuv_image(uint8_t *data[4], int linesize[4],
int width, int height, int frame_index)
{
int x, y, i;
i = frame_index;
/* Y */
for (y = 0; y < height; y++)
for (x = 0; x < width; x++)
data[0][y * linesize[0] + x] = x + y + i * 3;
/* Cb and Cr */
for (y = 0; y < height / 2; y++) {
for (x = 0; x < width / 2; x++) {
data[1][y * linesize[1] + x] = 128 + y + i * 2;
data[2][y * linesize[2] + x] = 64 + x + i * 5;
}
}
}
static void save_pgm(const char *filename,
const uint8_t *data, int linesize, int width, int height)
{
FILE *f;
int i;
f = fopen(filename, "w");
fprintf(f, "P5\n%d %d\n%d\n", width, height, 255);
for (i = 0; i < height; i++)
fwrite(data + i * linesize, 1, width, f);
fclose(f);
}
int main(int argc, char **argv)
{
uint8_t *src_data[4], *dst_data[4];
int src_linesize[4], dst_linesize[4];
int src_w = 320, src_h = 240, dst_w, dst_h;
enum PixelFormat src_pix_fmt = PIX_FMT_YUV420P, dst_pix_fmt = PIX_FMT_GRAY8;
const char *dst_size = argv[1];
struct SwsContext *sws_ctx;
int i, ret;
if (argc != 2) {
fprintf(stderr, "Usage: %s output_size\n"
"API example program to show how to scale an image with libswscale.\n"
"This program generates a series of pictures, rescales them to the given "
"<output size> and finally saves the rescaled pictures as PGM files named "
"like outscale<frame number>.pgm.\n"
"\n", argv[0]);
exit(1);
}
if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
av_log(NULL, AV_LOG_ERROR,
"Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
dst_size);
exit(1);
}
/* create scaling context */
sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
dst_w, dst_h, dst_pix_fmt,
SWS_BILINEAR, NULL, NULL, NULL);
if (!sws_ctx) {
av_log(NULL, AV_LOG_ERROR,
"Impossible to create scale context for the conversion "
"fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
av_get_pix_fmt_name(src_pix_fmt), src_w, src_h,
av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h);
ret = AVERROR(EINVAL);
goto end;
}
/* allocate source and destination image buffers */
if ((ret = av_image_alloc(src_data, src_linesize,
src_w, src_h, src_pix_fmt, 16)) < 0)
goto end;
if ((ret = av_image_alloc(dst_data, dst_linesize,
dst_w, dst_h, dst_pix_fmt, 16)) < 0)
goto end;
for (i = 0; i < 100; i++) {
char filename[1024];
/* generate synthetic video */
fill_yuv_image(src_data, src_linesize, src_w, src_h, i);
/* convert to destination format */
sws_scale(sws_ctx, (const uint8_t * const*)src_data,
src_linesize, 0, src_h, dst_data, dst_linesize);
/* write Y plane to to output PGM file */
snprintf(filename, sizeof(filename), "outscale%02d.pgm", i);
save_pgm(filename, dst_data[0], dst_linesize[0], dst_w, dst_h);
}
end:
av_freep(&src_data[0]);
av_freep(&dst_data[0]);
sws_freeContext(sws_ctx);
return ret < 0;
}
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