[FFmpeg-cvslog] examples: add scaling_video example
Stefano Sabatini
git at videolan.org
Tue Aug 28 20:10:39 CEST 2012
ffmpeg | branch: master | Stefano Sabatini <stefasab at gmail.com> | Tue Aug 21 14:43:51 2012 +0200| [74419fcf45359a9afc5a26b340ffb41d0edb746c] | committer: 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.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=74419fcf45359a9afc5a26b340ffb41d0edb746c
---
doc/examples/Makefile | 3 +-
doc/examples/scaling_video.c | 131 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 133 insertions(+), 1 deletion(-)
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index 5ef0f7b..94db383 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -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)
diff --git a/doc/examples/scaling_video.c b/doc/examples/scaling_video.c
new file mode 100644
index 0000000..61c5e8b
--- /dev/null
+++ b/doc/examples/scaling_video.c
@@ -0,0 +1,131 @@
+/*
+ * 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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