FFmpeg
scale_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 libswscale API usage example
25  * @example scale_video.c
26  *
27  * Generate a synthetic video signal and use libswscale to perform rescaling.
28  */
29 
30 #include <libavutil/imgutils.h>
31 #include <libavutil/parseutils.h>
32 #include <libswscale/swscale.h>
33 
34 static void fill_yuv_image(uint8_t *data[4], int linesize[4],
35  int width, int height, int frame_index)
36 {
37  int x, y;
38 
39  /* Y */
40  for (y = 0; y < height; y++)
41  for (x = 0; x < width; x++)
42  data[0][y * linesize[0] + x] = x + y + frame_index * 3;
43 
44  /* Cb and Cr */
45  for (y = 0; y < height / 2; y++) {
46  for (x = 0; x < width / 2; x++) {
47  data[1][y * linesize[1] + x] = 128 + y + frame_index * 2;
48  data[2][y * linesize[2] + x] = 64 + x + frame_index * 5;
49  }
50  }
51 }
52 
53 int main(int argc, char **argv)
54 {
55  uint8_t *src_data[4], *dst_data[4];
56  int src_linesize[4], dst_linesize[4];
57  int src_w = 320, src_h = 240, dst_w, dst_h;
58  enum AVPixelFormat src_pix_fmt = AV_PIX_FMT_YUV420P, dst_pix_fmt = AV_PIX_FMT_RGB24;
59  const char *dst_size = NULL;
60  const char *dst_filename = NULL;
61  FILE *dst_file;
62  int dst_bufsize;
63  struct SwsContext *sws_ctx;
64  int i, ret;
65 
66  if (argc != 3) {
67  fprintf(stderr, "Usage: %s output_file output_size\n"
68  "API example program to show how to scale an image with libswscale.\n"
69  "This program generates a series of pictures, rescales them to the given "
70  "output_size and saves them to an output file named output_file\n."
71  "\n", argv[0]);
72  exit(1);
73  }
74  dst_filename = argv[1];
75  dst_size = argv[2];
76 
77  if (av_parse_video_size(&dst_w, &dst_h, dst_size) < 0) {
78  fprintf(stderr,
79  "Invalid size '%s', must be in the form WxH or a valid size abbreviation\n",
80  dst_size);
81  exit(1);
82  }
83 
84  dst_file = fopen(dst_filename, "wb");
85  if (!dst_file) {
86  fprintf(stderr, "Could not open destination file %s\n", dst_filename);
87  exit(1);
88  }
89 
90  /* create scaling context */
91  sws_ctx = sws_getContext(src_w, src_h, src_pix_fmt,
92  dst_w, dst_h, dst_pix_fmt,
94  if (!sws_ctx) {
95  fprintf(stderr,
96  "Impossible to create scale context for the conversion "
97  "fmt:%s s:%dx%d -> fmt:%s s:%dx%d\n",
98  av_get_pix_fmt_name(src_pix_fmt), src_w, src_h,
99  av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h);
100  ret = AVERROR(EINVAL);
101  goto end;
102  }
103 
104  /* allocate source and destination image buffers */
105  if ((ret = av_image_alloc(src_data, src_linesize,
106  src_w, src_h, src_pix_fmt, 16)) < 0) {
107  fprintf(stderr, "Could not allocate source image\n");
108  goto end;
109  }
110 
111  /* buffer is going to be written to rawvideo file, no alignment */
112  if ((ret = av_image_alloc(dst_data, dst_linesize,
113  dst_w, dst_h, dst_pix_fmt, 1)) < 0) {
114  fprintf(stderr, "Could not allocate destination image\n");
115  goto end;
116  }
117  dst_bufsize = ret;
118 
119  for (i = 0; i < 100; i++) {
120  /* generate synthetic video */
121  fill_yuv_image(src_data, src_linesize, src_w, src_h, i);
122 
123  /* convert to destination format */
124  sws_scale(sws_ctx, (const uint8_t * const*)src_data,
125  src_linesize, 0, src_h, dst_data, dst_linesize);
126 
127  /* write scaled image to file */
128  fwrite(dst_data[0], 1, dst_bufsize, dst_file);
129  }
130 
131  fprintf(stderr, "Scaling succeeded. Play the output file with the command:\n"
132  "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
133  av_get_pix_fmt_name(dst_pix_fmt), dst_w, dst_h, dst_filename);
134 
135 end:
136  fclose(dst_file);
137  av_freep(&src_data[0]);
138  av_freep(&dst_data[0]);
139  sws_freeContext(sws_ctx);
140  return ret < 0;
141 }
AVPixelFormat
AVPixelFormat
Pixel format.
Definition: pixfmt.h:71
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
data
const char data[16]
Definition: mxf.c:148
sws_scale
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:1205
width
#define width
AV_PIX_FMT_YUV420P
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:73
NULL
#define NULL
Definition: coverity.c:32
parseutils.h
av_image_alloc
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:218
AV_PIX_FMT_RGB24
@ AV_PIX_FMT_RGB24
packed RGB 8:8:8, 24bpp, RGBRGB...
Definition: pixfmt.h:75
sws_getContext
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:2094
height
#define height
av_parse_video_size
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:150
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:245
ret
ret
Definition: filter_design.txt:187
sws_freeContext
void sws_freeContext(struct SwsContext *swsContext)
Free the swscaler context swsContext.
Definition: utils.c:2425
fill_yuv_image
static void fill_yuv_image(uint8_t *data[4], int linesize[4], int width, int height, int frame_index)
Definition: scale_video.c:34
main
int main(int argc, char **argv)
Definition: scale_video.c:53
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
imgutils.h
SWS_BILINEAR
#define SWS_BILINEAR
Definition: swscale.h:66
SwsContext
Definition: swscale_internal.h:299
swscale.h
av_get_pix_fmt_name
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:2888