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scaling_video.c
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1 /*
2  * Copyright (c) 2012 Stefano Sabatini
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a copy
5  * of this software and associated documentation files (the "Software"), to deal
6  * in the Software without restriction, including without limitation the rights
7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8  * copies of the Software, and to permit persons to whom the Software is
9  * furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  * THE SOFTWARE.
21  */
22 
23 /**
24  * @file
25  * libswscale API use example.
26  * @example scaling_video.c
27  */
28 
29 #include <libavutil/imgutils.h>
30 #include <libavutil/parseutils.h>
31 #include <libswscale/swscale.h>
32 
33 static void fill_yuv_image(uint8_t *data[4], int linesize[4],
34  int width, int height, int frame_index)
35 {
36  int x, y;
37 
38  /* Y */
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;
42 
43  /* Cb and Cr */
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;
48  }
49  }
50 }
51 
52 int main(int argc, char **argv)
53 {
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;
60  FILE *dst_file;
61  int dst_bufsize;
62  struct SwsContext *sws_ctx;
63  int i, ret;
64 
65  if (argc != 3) {
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."
70  "\n", argv[0]);
71  exit(1);
72  }
73  dst_filename = argv[1];
74  dst_size = argv[2];
75 
76  if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
77  fprintf(stderr,
78  "Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
79  dst_size);
80  exit(1);
81  }
82 
83  dst_file = fopen(dst_filename, "wb");
84  if (!dst_file) {
85  fprintf(stderr, "Could not open destination file %s\n", dst_filename);
86  exit(1);
87  }
88 
89  /* create scaling context */
90  sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
91  dst_w, dst_h, dst_pix_fmt,
93  if (!sws_ctx) {
94  fprintf(stderr,
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);
100  goto end;
101  }
102 
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");
107  goto end;
108  }
109 
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");
114  goto end;
115  }
116  dst_bufsize = ret;
117 
118  for (i = 0; i < 100; i++) {
119  /* generate synthetic video */
120  fill_yuv_image(src_data, src_linesize, src_w, src_h, i);
121 
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);
125 
126  /* write scaled image to file */
127  fwrite(dst_data[0], 1, dst_bufsize, dst_file);
128  }
129 
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);
133 
134 end:
135  fclose(dst_file);
136  av_freep(&src_data[0]);
137  av_freep(&dst_data[0]);
138  sws_freeContext(sws_ctx);
139  return ret < 0;
140 }
#define NULL
Definition: coverity.c:32
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
int av_parse_video_size(int *width_ptr, int *height_ptr, const char *str)
Parse str and put in width_ptr and height_ptr the detected values.
Definition: parseutils.c:143
misc image utilities
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:64
int av_image_alloc(uint8_t *pointers[4], int linesizes[4], int w, int h, enum AVPixelFormat pix_fmt, int align)
Allocate an image with size w and h and pixel format pix_fmt, and fill pointers and linesizes accordi...
Definition: imgutils.c:191
#define SWS_BILINEAR
Definition: swscale.h:57
uint8_t
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
#define height
struct SwsContext * sws_getContext(int srcW, int srcH, enum AVPixelFormat srcFormat, int dstW, int dstH, enum AVPixelFormat dstFormat, int flags, SwsFilter *srcFilter, SwsFilter *dstFilter, const double *param)
Allocate and return an SwsContext.
Definition: utils.c:1854
external API header
#define AVERROR(e)
Definition: error.h:43
#define width
static void fill_yuv_image(uint8_t *data[4], int linesize[4], int width, int height, int frame_index)
Definition: scaling_video.c:33
void sws_freeContext(struct SwsContext *swsContext)
Free the swscaler context swsContext.
Definition: utils.c:2274
int attribute_align_arg sws_scale(struct SwsContext *c, const uint8_t *const srcSlice[], const int srcStride[], int srcSliceY, int srcSliceH, uint8_t *const dst[], const int dstStride[])
swscale wrapper, so we don't need to export the SwsContext.
Definition: swscale.c:753
misc parsing utilities
int main(int argc, char **argv)
Definition: scaling_video.c:52
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:62
#define av_freep(p)
const char * av_get_pix_fmt_name(enum AVPixelFormat pix_fmt)
Return the short name for a pixel format, NULL in case pix_fmt is unknown.
Definition: pixdesc.c:2179
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60