[FFmpeg-devel] [PATCH] examples/scaling_video: write to rawvideo file

[Stefano Sabatini]

This is more useful for test purposes. Also allow to specify the name of
the output file.
---
 doc/examples/scaling_video.c |   52 +++++++++++++++++++++--------------------
 1 files changed, 27 insertions(+), 25 deletions(-)

diff --git a/doc/examples/scaling_video.c b/doc/examples/scaling_video.c
index 144b54a..a53b148 100644
--- a/doc/examples/scaling_video.c
+++ b/doc/examples/scaling_video.c
@@ -50,38 +50,29 @@ static void fill_yuv_image(uint8_t *data[4], int linesize[4],
     }
 }
 
-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];
+    enum PixelFormat src_pix_fmt = PIX_FMT_YUV420P, dst_pix_fmt = 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 != 2) {
-        fprintf(stderr, "Usage: %s output_size\n"
+    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 finally saves the rescaled pictures as PGM files named "
-                "like outscale<frame number>.pgm.\n"
+                "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,
@@ -90,6 +81,12 @@ int main(int argc, char **argv)
         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,
@@ -109,13 +106,13 @@ int main(int argc, char **argv)
                               src_w, src_h, src_pix_fmt, 16)) < 0)
         goto end;
 
+    /* buffer is going to be written to rawvideo file, no alignmnet */
     if ((ret = av_image_alloc(dst_data, dst_linesize,
-                              dst_w, dst_h, dst_pix_fmt, 16)) < 0)
+                              dst_w, dst_h, dst_pix_fmt, 1)) < 0)
         goto end;
+    dst_bufsize = ret;
 
     for (i = 0; i < 100; i++) {
-        char filename[1024];
-
         /* generate synthetic video */
         fill_yuv_image(src_data, src_linesize, src_w, src_h, i);
 
@@ -123,12 +120,17 @@ int main(int argc, char **argv)
         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);
+        /* 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:
+    if (dst_file)
+        fclose(dst_file);
     av_freep(&src_data[0]);
     av_freep(&dst_data[0]);
     sws_freeContext(sws_ctx);
-- 
1.7.5.4