1 files changed, 140 insertions, 0 deletions
diff --git a/doc/examples/scaling_video.c b/doc/examples/scaling_video.c
new file mode 100644
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--- /dev/null
+++ b/doc/examples/scaling_video.c
@@ -0,0 +1,140 @@
+/*
+ * 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.
+ */
+
+/**
+ * @file
+ * libswscale API use example.
+ * @example scaling_video.c
+ */
+
+#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;
+
+    /* Y */
+    for (y = 0; y < height; y++)
+        for (x = 0; x < width; x++)
+            data[0][y * linesize[0] + x] = x + y + frame_index * 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 + frame_index * 2;
+            data[2][y * linesize[2] + x] = 64 + x + frame_index * 5;
+        }
+    }
+}
+
+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 AVPixelFormat src_pix_fmt = AV_PIX_FMT_YUV420P, dst_pix_fmt = AV_PIX_FMT_RGB24;
+    const char *dst_size = NULL;
+    const char *dst_filename = NULL;
+    FILE *dst_file;
+    int dst_bufsize;
+    struct SwsContext *sws_ctx;
+    int i, ret;
+
+    if (argc != 3) {
+        fprintf(stderr, "Usage: %s output_file 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 saves them to an output file named output_file\n."
+                "\n", argv[0]);
+        exit(1);
+    }
+    dst_filename = argv[1];
+    dst_size     = argv[2];
+
+    if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
+        fprintf(stderr,
+                "Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
+                dst_size);
+        exit(1);
+    }
+
+    dst_file = fopen(dst_filename, "wb");
+    if (!dst_file) {
+        fprintf(stderr, "Could not open destination file %s\n", dst_filename);
+        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) {
+        fprintf(stderr,
+                "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) {
+        fprintf(stderr, "Could not allocate source image\n");
+        goto end;
+    }
+
+    /* buffer is going to be written to rawvideo file, no alignment */
+    if ((ret = av_image_alloc(dst_data, dst_linesize,
+                              dst_w, dst_h, dst_pix_fmt, 1)) < 0) {
+        fprintf(stderr, "Could not allocate destination image\n");
+        goto end;
+    }
+    dst_bufsize = ret;
+
+    for (i = 0; i < 100; i++) {
+        /* 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 scaled image to file */
+        fwrite(dst_data[0], 1, dst_bufsize, dst_file);
+    }
+
+    fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
+           "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
+           av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename);
+
+end:
+    fclose(dst_file);
+    av_freep(&src_data[0]);
+    av_freep(&dst_data[0]);
+    sws_freeContext(sws_ctx);
+    return ret < 0;
+}