2 * Copyright (c) 2012 Stefano Sabatini
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25 * libswscale API use example.
26 * @example scaling_video.c
29 #include <libavutil/imgutils.h>
30 #include <libavutil/parseutils.h>
31 #include <libswscale/swscale.h>
33 static void fill_yuv_image(uint8_t *data
[4], int linesize
[4],
34 int width
, int height
, int frame_index
)
39 for (y
= 0; y
< height
; y
++)
40 for (x
= 0; x
< width
; x
++)
41 data
[0][y
* linesize
[0] + x
] = x
+ y
+ frame_index
* 3;
44 for (y
= 0; y
< height
/ 2; y
++) {
45 for (x
= 0; x
< width
/ 2; x
++) {
46 data
[1][y
* linesize
[1] + x
] = 128 + y
+ frame_index
* 2;
47 data
[2][y
* linesize
[2] + x
] = 64 + x
+ frame_index
* 5;
52 int main(int argc
, char **argv
)
54 uint8_t *src_data
[4], *dst_data
[4];
55 int src_linesize
[4], dst_linesize
[4];
56 int src_w
= 320, src_h
= 240, dst_w
, dst_h
;
57 enum AVPixelFormat src_pix_fmt
= AV_PIX_FMT_YUV420P
, dst_pix_fmt
= AV_PIX_FMT_RGB24
;
58 const char *dst_size
= NULL
;
59 const char *dst_filename
= NULL
;
62 struct SwsContext
*sws_ctx
;
66 fprintf(stderr
, "Usage: %s output_file output_size\n"
67 "API example program to show how to scale an image with libswscale.\n"
68 "This program generates a series of pictures, rescales them to the given "
69 "output_size and saves them to an output file named output_file\n."
73 dst_filename
= argv
[1];
76 if (av_parse_video_size(&dst_w
, &dst_h
, dst_size
) < 0) {
78 "Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
83 dst_file
= fopen(dst_filename
, "wb");
85 fprintf(stderr
, "Could not open destination file %s\n", dst_filename
);
89 /* create scaling context */
90 sws_ctx
= sws_getContext(src_w
, src_h
, src_pix_fmt
,
91 dst_w
, dst_h
, dst_pix_fmt
,
92 SWS_BILINEAR
, NULL
, NULL
, NULL
);
95 "Impossible to create scale context for the conversion "
96 "fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
97 av_get_pix_fmt_name(src_pix_fmt
), src_w
, src_h
,
98 av_get_pix_fmt_name(dst_pix_fmt
), dst_w
, dst_h
);
99 ret
= AVERROR(EINVAL
);
103 /* allocate source and destination image buffers */
104 if ((ret
= av_image_alloc(src_data
, src_linesize
,
105 src_w
, src_h
, src_pix_fmt
, 16)) < 0) {
106 fprintf(stderr
, "Could not allocate source image\n");
110 /* buffer is going to be written to rawvideo file, no alignment */
111 if ((ret
= av_image_alloc(dst_data
, dst_linesize
,
112 dst_w
, dst_h
, dst_pix_fmt
, 1)) < 0) {
113 fprintf(stderr
, "Could not allocate destination image\n");
118 for (i
= 0; i
< 100; i
++) {
119 /* generate synthetic video */
120 fill_yuv_image(src_data
, src_linesize
, src_w
, src_h
, i
);
122 /* convert to destination format */
123 sws_scale(sws_ctx
, (const uint8_t * const*)src_data
,
124 src_linesize
, 0, src_h
, dst_data
, dst_linesize
);
126 /* write scaled image to file */
127 fwrite(dst_data
[0], 1, dst_bufsize
, dst_file
);
130 fprintf(stderr
, "Scaling succeeded. Play the output file with the command:\n"
131 "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
132 av_get_pix_fmt_name(dst_pix_fmt
), dst_w
, dst_h
, dst_filename
);
136 av_freep(&src_data
[0]);
137 av_freep(&dst_data
[0]);
138 sws_freeContext(sws_ctx
);