2 * Copyright (c) 2010 Nicolas George
3 * Copyright (c) 2011 Stefano Sabatini
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:
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
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
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>
39 #include <libavutil/opt.h>
41 const char *filter_descr = "scale=78:24";
43 static AVFormatContext *fmt_ctx;
44 static AVCodecContext *dec_ctx;
45 AVFilterContext *buffersink_ctx;
46 AVFilterContext *buffersrc_ctx;
47 AVFilterGraph *filter_graph;
48 static int video_stream_index = -1;
49 static int64_t last_pts = AV_NOPTS_VALUE;
51 static int open_input_file(const char *filename)
56 if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
57 av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
61 if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
62 av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
66 /* select the video stream */
67 ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
69 av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
72 video_stream_index = ret;
73 dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
74 av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
76 /* init the video decoder */
77 if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
78 av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
85 static int init_filters(const char *filters_descr)
89 AVFilter *buffersrc = avfilter_get_by_name("buffer");
90 AVFilter *buffersink = avfilter_get_by_name("buffersink");
91 AVFilterInOut *outputs = avfilter_inout_alloc();
92 AVFilterInOut *inputs = avfilter_inout_alloc();
93 enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
95 filter_graph = avfilter_graph_alloc();
96 if (!outputs || !inputs || !filter_graph) {
97 ret = AVERROR(ENOMEM);
101 /* buffer video source: the decoded frames from the decoder will be inserted here. */
102 snprintf(args, sizeof(args),
103 "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
104 dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
105 dec_ctx->time_base.num, dec_ctx->time_base.den,
106 dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
108 ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
109 args, NULL, filter_graph);
111 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
115 /* buffer video sink: to terminate the filter chain. */
116 ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
117 NULL, NULL, filter_graph);
119 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
123 ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
124 AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
126 av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
130 /* Endpoints for the filter graph. */
131 outputs->name = av_strdup("in");
132 outputs->filter_ctx = buffersrc_ctx;
133 outputs->pad_idx = 0;
134 outputs->next = NULL;
136 inputs->name = av_strdup("out");
137 inputs->filter_ctx = buffersink_ctx;
141 if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
142 &inputs, &outputs, NULL)) < 0)
145 if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
149 avfilter_inout_free(&inputs);
150 avfilter_inout_free(&outputs);
155 static void display_frame(const AVFrame *frame, AVRational time_base)
161 if (frame->pts != AV_NOPTS_VALUE) {
162 if (last_pts != AV_NOPTS_VALUE) {
163 /* sleep roughly the right amount of time;
164 * usleep is in microseconds, just like AV_TIME_BASE. */
165 delay = av_rescale_q(frame->pts - last_pts,
166 time_base, AV_TIME_BASE_Q);
167 if (delay > 0 && delay < 1000000)
170 last_pts = frame->pts;
173 /* Trivial ASCII grayscale display. */
176 for (y = 0; y < frame->height; y++) {
178 for (x = 0; x < frame->width; x++)
179 putchar(" .-+#"[*(p++) / 52]);
181 p0 += frame->linesize[0];
186 int main(int argc, char **argv)
190 AVFrame *frame = av_frame_alloc();
191 AVFrame *filt_frame = av_frame_alloc();
194 if (!frame || !filt_frame) {
195 perror("Could not allocate frame");
199 fprintf(stderr, "Usage: %s file\n", argv[0]);
203 avcodec_register_all();
205 avfilter_register_all();
207 if ((ret = open_input_file(argv[1])) < 0)
209 if ((ret = init_filters(filter_descr)) < 0)
212 /* read all packets */
214 if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
217 if (packet.stream_index == video_stream_index) {
218 avcodec_get_frame_defaults(frame);
220 ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
222 av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
227 frame->pts = av_frame_get_best_effort_timestamp(frame);
229 /* push the decoded frame into the filtergraph */
230 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
231 av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
235 /* pull filtered frames from the filtergraph */
237 ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
238 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
242 display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
243 av_frame_unref(filt_frame);
245 av_frame_unref(frame);
248 av_free_packet(&packet);
251 avfilter_graph_free(&filter_graph);
252 avcodec_close(dec_ctx);
253 avformat_close_input(&fmt_ctx);
254 av_frame_free(&frame);
255 av_frame_free(&filt_frame);
257 if (ret < 0 && ret != AVERROR_EOF) {
258 fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));