2 * Copyright (c) 2010 Nicolas George
3 * Copyright (c) 2011 Stefano Sabatini
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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:
12 * The above copyright notice and this permission notice shall be included in
13 * all copies or substantial portions of the Software.
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
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20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
26 * API example for decoding and filtering
27 * @example doc/examples/filtering_video.c
30 #define _XOPEN_SOURCE 600 /* for usleep */
33 #include <libavcodec/avcodec.h>
34 #include <libavformat/avformat.h>
35 #include <libavfilter/avfiltergraph.h>
36 #include <libavfilter/avcodec.h>
37 #include <libavfilter/buffersink.h>
38 #include <libavfilter/buffersrc.h>
40 const char *filter_descr = "scale=78:24";
42 static AVFormatContext *fmt_ctx;
43 static AVCodecContext *dec_ctx;
44 AVFilterContext *buffersink_ctx;
45 AVFilterContext *buffersrc_ctx;
46 AVFilterGraph *filter_graph;
47 static int video_stream_index = -1;
48 static int64_t last_pts = AV_NOPTS_VALUE;
50 static int open_input_file(const char *filename)
55 if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
56 av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
60 if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
61 av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
65 /* select the video stream */
66 ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
68 av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
71 video_stream_index = ret;
72 dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
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");
83 static int init_filters(const char *filters_descr)
87 AVFilter *buffersrc = avfilter_get_by_name("buffer");
88 AVFilter *buffersink = avfilter_get_by_name("buffersink");
89 AVFilterInOut *outputs = avfilter_inout_alloc();
90 AVFilterInOut *inputs = avfilter_inout_alloc();
91 enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
92 AVBufferSinkParams *buffersink_params;
94 filter_graph = avfilter_graph_alloc();
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);
103 ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
104 args, NULL, filter_graph);
106 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
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);
117 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
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;
127 inputs->name = av_strdup("out");
128 inputs->filter_ctx = buffersink_ctx;
132 if ((ret = avfilter_graph_parse(filter_graph, filters_descr,
133 &inputs, &outputs, NULL)) < 0)
136 if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
141 static void display_picref(AVFilterBufferRef *picref, AVRational time_base)
147 if (picref->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(picref->pts - last_pts,
152 time_base, AV_TIME_BASE_Q);
153 if (delay > 0 && delay < 1000000)
156 last_pts = picref->pts;
159 /* Trivial ASCII grayscale display. */
160 p0 = picref->data[0];
162 for (y = 0; y < picref->video->h; y++) {
164 for (x = 0; x < picref->video->w; x++)
165 putchar(" .-+#"[*(p++) / 52]);
167 p0 += picref->linesize[0];
172 int main(int argc, char **argv)
176 AVFrame *frame = avcodec_alloc_frame();
180 perror("Could not allocate frame");
184 fprintf(stderr, "Usage: %s file\n", argv[0]);
188 avcodec_register_all();
190 avfilter_register_all();
192 if ((ret = open_input_file(argv[1])) < 0)
194 if ((ret = init_filters(filter_descr)) < 0)
197 /* read all packets */
199 AVFilterBufferRef *picref;
200 if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
203 if (packet.stream_index == video_stream_index) {
204 avcodec_get_frame_defaults(frame);
206 ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
208 av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
213 frame->pts = av_frame_get_best_effort_timestamp(frame);
215 /* push the decoded frame into the filtergraph */
216 if (av_buffersrc_add_frame(buffersrc_ctx, frame) < 0) {
217 av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
221 /* pull filtered pictures from the filtergraph */
223 ret = av_buffersink_get_buffer_ref(buffersink_ctx, &picref, 0);
224 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
230 display_picref(picref, buffersink_ctx->inputs[0]->time_base);
231 avfilter_unref_bufferp(&picref);
236 av_free_packet(&packet);
239 avfilter_graph_free(&filter_graph);
241 avcodec_close(dec_ctx);
242 avformat_close_input(&fmt_ctx);
245 if (ret < 0 && ret != AVERROR_EOF) {
247 av_strerror(ret, buf, sizeof(buf));
248 fprintf(stderr, "Error occurred: %s\n", buf);