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 filtering_video.c
30 #define _XOPEN_SOURCE 600 /* for usleep */
35 #include <libavcodec/avcodec.h>
36 #include <libavformat/avformat.h>
37 #include <libavfilter/buffersink.h>
38 #include <libavfilter/buffersrc.h>
39 #include <libavutil/opt.h>
41 const char *filter_descr = "scale=78:24,transpose=cclock";
43 scale=78:24 [scl]; [scl] transpose=cclock // assumes "[in]" and "[out]" to be input output pads respectively
46 static AVFormatContext *fmt_ctx;
47 static AVCodecContext *dec_ctx;
48 AVFilterContext *buffersink_ctx;
49 AVFilterContext *buffersrc_ctx;
50 AVFilterGraph *filter_graph;
51 static int video_stream_index = -1;
52 static int64_t last_pts = AV_NOPTS_VALUE;
54 static int open_input_file(const char *filename)
59 if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
60 av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
64 if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
65 av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
69 /* select the video stream */
70 ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
72 av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
75 video_stream_index = ret;
77 /* create decoding context */
78 dec_ctx = avcodec_alloc_context3(dec);
80 return AVERROR(ENOMEM);
81 avcodec_parameters_to_context(dec_ctx, fmt_ctx->streams[video_stream_index]->codecpar);
83 /* init the video decoder */
84 if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
85 av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
92 static int init_filters(const char *filters_descr)
96 const AVFilter *buffersrc = avfilter_get_by_name("buffer");
97 const AVFilter *buffersink = avfilter_get_by_name("buffersink");
98 AVFilterInOut *outputs = avfilter_inout_alloc();
99 AVFilterInOut *inputs = avfilter_inout_alloc();
100 AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
101 enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
103 filter_graph = avfilter_graph_alloc();
104 if (!outputs || !inputs || !filter_graph) {
105 ret = AVERROR(ENOMEM);
109 /* buffer video source: the decoded frames from the decoder will be inserted here. */
110 snprintf(args, sizeof(args),
111 "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
112 dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
113 time_base.num, time_base.den,
114 dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
116 ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
117 args, NULL, filter_graph);
119 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
123 /* buffer video sink: to terminate the filter chain. */
124 ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
125 NULL, NULL, filter_graph);
127 av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
131 ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
132 AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
134 av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
139 * Set the endpoints for the filter graph. The filter_graph will
140 * be linked to the graph described by filters_descr.
144 * The buffer source output must be connected to the input pad of
145 * the first filter described by filters_descr; since the first
146 * filter input label is not specified, it is set to "in" by
149 outputs->name = av_strdup("in");
150 outputs->filter_ctx = buffersrc_ctx;
151 outputs->pad_idx = 0;
152 outputs->next = NULL;
155 * The buffer sink input must be connected to the output pad of
156 * the last filter described by filters_descr; since the last
157 * filter output label is not specified, it is set to "out" by
160 inputs->name = av_strdup("out");
161 inputs->filter_ctx = buffersink_ctx;
165 if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
166 &inputs, &outputs, NULL)) < 0)
169 if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
173 avfilter_inout_free(&inputs);
174 avfilter_inout_free(&outputs);
179 static void display_frame(const AVFrame *frame, AVRational time_base)
185 if (frame->pts != AV_NOPTS_VALUE) {
186 if (last_pts != AV_NOPTS_VALUE) {
187 /* sleep roughly the right amount of time;
188 * usleep is in microseconds, just like AV_TIME_BASE. */
189 delay = av_rescale_q(frame->pts - last_pts,
190 time_base, AV_TIME_BASE_Q);
191 if (delay > 0 && delay < 1000000)
194 last_pts = frame->pts;
197 /* Trivial ASCII grayscale display. */
200 for (y = 0; y < frame->height; y++) {
202 for (x = 0; x < frame->width; x++)
203 putchar(" .-+#"[*(p++) / 52]);
205 p0 += frame->linesize[0];
210 int main(int argc, char **argv)
218 fprintf(stderr, "Usage: %s file\n", argv[0]);
222 frame = av_frame_alloc();
223 filt_frame = av_frame_alloc();
224 if (!frame || !filt_frame) {
225 perror("Could not allocate frame");
229 if ((ret = open_input_file(argv[1])) < 0)
231 if ((ret = init_filters(filter_descr)) < 0)
234 /* read all packets */
236 if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
239 if (packet.stream_index == video_stream_index) {
240 ret = avcodec_send_packet(dec_ctx, &packet);
242 av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
247 ret = avcodec_receive_frame(dec_ctx, frame);
248 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
250 } else if (ret < 0) {
251 av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
255 frame->pts = frame->best_effort_timestamp;
257 /* push the decoded frame into the filtergraph */
258 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
259 av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
263 /* pull filtered frames from the filtergraph */
265 ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
266 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
270 display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
271 av_frame_unref(filt_frame);
273 av_frame_unref(frame);
276 av_packet_unref(&packet);
279 avfilter_graph_free(&filter_graph);
280 avcodec_free_context(&dec_ctx);
281 avformat_close_input(&fmt_ctx);
282 av_frame_free(&frame);
283 av_frame_free(&filt_frame);
285 if (ret < 0 && ret != AVERROR_EOF) {
286 fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));