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filtering_video.c
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1 /*
2  * Copyright (c) 2010 Nicolas George
3  * Copyright (c) 2011 Stefano Sabatini
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining a copy
6  * of this software and associated documentation files (the "Software"), to deal
7  * in the Software without restriction, including without limitation the rights
8  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9  * copies of the Software, and to permit persons to whom the Software is
10  * furnished to do so, subject to the following conditions:
11  *
12  * The above copyright notice and this permission notice shall be included in
13  * all copies or substantial portions of the Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21  * THE SOFTWARE.
22  */
23 
24 /**
25  * @file
26  * API example for decoding and filtering
27  * @example doc/examples/filtering_video.c
28  */
29 
30 #define _XOPEN_SOURCE 600 /* for usleep */
31 #include <unistd.h>
32 
33 #include <libavcodec/avcodec.h>
34 #include <libavformat/avformat.h>
36 #include <libavfilter/avcodec.h>
37 #include <libavfilter/buffersink.h>
38 #include <libavfilter/buffersrc.h>
39 
40 const char *filter_descr = "scale=78:24";
41 
47 static int video_stream_index = -1;
48 static int64_t last_pts = AV_NOPTS_VALUE;
49 
50 static int open_input_file(const char *filename)
51 {
52  int ret;
53  AVCodec *dec;
54 
55  if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
56  av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
57  return ret;
58  }
59 
60  if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
61  av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
62  return ret;
63  }
64 
65  /* select the video stream */
66  ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
67  if (ret < 0) {
68  av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
69  return ret;
70  }
72  dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
73 
74  /* init the video decoder */
75  if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
76  av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
77  return ret;
78  }
79 
80  return 0;
81 }
82 
83 static int init_filters(const char *filters_descr)
84 {
85  char args[512];
86  int ret;
87  AVFilter *buffersrc = avfilter_get_by_name("buffer");
88  AVFilter *buffersink = avfilter_get_by_name("buffersink");
91  enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
92  AVBufferSinkParams *buffersink_params;
93 
94  filter_graph = avfilter_graph_alloc();
95 
96  /* buffer video source: the decoded frames from the decoder will be inserted here. */
97  snprintf(args, sizeof(args),
98  "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
99  dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
100  dec_ctx->time_base.num, dec_ctx->time_base.den,
101  dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
102 
103  ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
104  args, NULL, filter_graph);
105  if (ret < 0) {
106  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
107  return ret;
108  }
109 
110  /* buffer video sink: to terminate the filter chain. */
111  buffersink_params = av_buffersink_params_alloc();
112  buffersink_params->pixel_fmts = pix_fmts;
113  ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
114  NULL, buffersink_params, filter_graph);
115  av_free(buffersink_params);
116  if (ret < 0) {
117  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
118  return ret;
119  }
120 
121  /* Endpoints for the filter graph. */
122  outputs->name = av_strdup("in");
123  outputs->filter_ctx = buffersrc_ctx;
124  outputs->pad_idx = 0;
125  outputs->next = NULL;
126 
127  inputs->name = av_strdup("out");
128  inputs->filter_ctx = buffersink_ctx;
129  inputs->pad_idx = 0;
130  inputs->next = NULL;
131 
132  if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
133  &inputs, &outputs, NULL)) < 0)
134  return ret;
135 
136  if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
137  return ret;
138  return 0;
139 }
140 
141 static void display_frame(const AVFrame *frame, AVRational time_base)
142 {
143  int x, y;
144  uint8_t *p0, *p;
145  int64_t delay;
146 
147  if (frame->pts != AV_NOPTS_VALUE) {
148  if (last_pts != AV_NOPTS_VALUE) {
149  /* sleep roughly the right amount of time;
150  * usleep is in microseconds, just like AV_TIME_BASE. */
151  delay = av_rescale_q(frame->pts - last_pts,
152  time_base, AV_TIME_BASE_Q);
153  if (delay > 0 && delay < 1000000)
154  usleep(delay);
155  }
156  last_pts = frame->pts;
157  }
158 
159  /* Trivial ASCII grayscale display. */
160  p0 = frame->data[0];
161  puts("\033c");
162  for (y = 0; y < frame->height; y++) {
163  p = p0;
164  for (x = 0; x < frame->width; x++)
165  putchar(" .-+#"[*(p++) / 52]);
166  putchar('\n');
167  p0 += frame->linesize[0];
168  }
169  fflush(stdout);
170 }
171 
172 int main(int argc, char **argv)
173 {
174  int ret;
175  AVPacket packet;
177  AVFrame *filt_frame = av_frame_alloc();
178  int got_frame;
179 
180  if (!frame || !filt_frame) {
181  perror("Could not allocate frame");
182  exit(1);
183  }
184  if (argc != 2) {
185  fprintf(stderr, "Usage: %s file\n", argv[0]);
186  exit(1);
187  }
188 
190  av_register_all();
192 
193  if ((ret = open_input_file(argv[1])) < 0)
194  goto end;
195  if ((ret = init_filters(filter_descr)) < 0)
196  goto end;
197 
198  /* read all packets */
199  while (1) {
200  if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
201  break;
202 
203  if (packet.stream_index == video_stream_index) {
205  got_frame = 0;
206  ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
207  if (ret < 0) {
208  av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
209  break;
210  }
211 
212  if (got_frame) {
213  frame->pts = av_frame_get_best_effort_timestamp(frame);
214 
215  /* push the decoded frame into the filtergraph */
216  if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
217  av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
218  break;
219  }
220 
221  /* pull filtered frames from the filtergraph */
222  while (1) {
223  ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
224  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
225  break;
226  if (ret < 0)
227  goto end;
228  display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
229  av_frame_unref(filt_frame);
230  }
231  }
232  }
233  av_free_packet(&packet);
234  }
235 end:
236  avfilter_graph_free(&filter_graph);
237  if (dec_ctx)
238  avcodec_close(dec_ctx);
239  avformat_close_input(&fmt_ctx);
240  av_frame_free(&frame);
241  av_frame_free(&filt_frame);
242 
243  if (ret < 0 && ret != AVERROR_EOF) {
244  char buf[1024];
245  av_strerror(ret, buf, sizeof(buf));
246  fprintf(stderr, "Error occurred: %s\n", buf);
247  exit(1);
248  }
249 
250  exit(0);
251 }