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 filtering_video.c
28  */
29 
30 #define _XOPEN_SOURCE 600 /* for usleep */
31 #include <unistd.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 
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>
40 
41 const char *filter_descr = "scale=78:24,transpose=cclock";
42 /* other way:
43    scale=78:24 [scl]; [scl] transpose=cclock // assumes "[in]" and "[out]" to be input output pads respectively
44  */
45 
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;
53 
open_input_file(const char * filename)54 static int open_input_file(const char *filename)
55 {
56     int ret;
57     AVCodec *dec;
58 
59     if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
60         av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
61         return ret;
62     }
63 
64     if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
65         av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
66         return ret;
67     }
68 
69     /* select the video stream */
70     ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
71     if (ret < 0) {
72         av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
73         return ret;
74     }
75     video_stream_index = ret;
76 
77     /* create decoding context */
78     dec_ctx = avcodec_alloc_context3(dec);
79     if (!dec_ctx)
80         return AVERROR(ENOMEM);
81     avcodec_parameters_to_context(dec_ctx, fmt_ctx->streams[video_stream_index]->codecpar);
82 
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");
86         return ret;
87     }
88 
89     return 0;
90 }
91 
init_filters(const char * filters_descr)92 static int init_filters(const char *filters_descr)
93 {
94     char args[512];
95     int ret = 0;
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 };
102 
103     filter_graph = avfilter_graph_alloc();
104     if (!outputs || !inputs || !filter_graph) {
105         ret = AVERROR(ENOMEM);
106         goto end;
107     }
108 
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);
115 
116     ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
117                                        args, NULL, filter_graph);
118     if (ret < 0) {
119         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
120         goto end;
121     }
122 
123     /* buffer video sink: to terminate the filter chain. */
124     ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
125                                        NULL, NULL, filter_graph);
126     if (ret < 0) {
127         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
128         goto end;
129     }
130 
131     ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
132                               AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
133     if (ret < 0) {
134         av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
135         goto end;
136     }
137 
138     /*
139      * Set the endpoints for the filter graph. The filter_graph will
140      * be linked to the graph described by filters_descr.
141      */
142 
143     /*
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
147      * default.
148      */
149     outputs->name       = av_strdup("in");
150     outputs->filter_ctx = buffersrc_ctx;
151     outputs->pad_idx    = 0;
152     outputs->next       = NULL;
153 
154     /*
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
158      * default.
159      */
160     inputs->name       = av_strdup("out");
161     inputs->filter_ctx = buffersink_ctx;
162     inputs->pad_idx    = 0;
163     inputs->next       = NULL;
164 
165     if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
166                                     &inputs, &outputs, NULL)) < 0)
167         goto end;
168 
169     if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
170         goto end;
171 
172 end:
173     avfilter_inout_free(&inputs);
174     avfilter_inout_free(&outputs);
175 
176     return ret;
177 }
178 
display_frame(const AVFrame * frame,AVRational time_base)179 static void display_frame(const AVFrame *frame, AVRational time_base)
180 {
181     int x, y;
182     uint8_t *p0, *p;
183     int64_t delay;
184 
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)
192                 usleep(delay);
193         }
194         last_pts = frame->pts;
195     }
196 
197     /* Trivial ASCII grayscale display. */
198     p0 = frame->data[0];
199     puts("\033c");
200     for (y = 0; y < frame->height; y++) {
201         p = p0;
202         for (x = 0; x < frame->width; x++)
203             putchar(" .-+#"[*(p++) / 52]);
204         putchar('\n');
205         p0 += frame->linesize[0];
206     }
207     fflush(stdout);
208 }
209 
main(int argc,char ** argv)210 int main(int argc, char **argv)
211 {
212     int ret;
213     AVPacket packet;
214     AVFrame *frame;
215     AVFrame *filt_frame;
216 
217     if (argc != 2) {
218         fprintf(stderr, "Usage: %s file\n", argv[0]);
219         exit(1);
220     }
221 
222     frame = av_frame_alloc();
223     filt_frame = av_frame_alloc();
224     if (!frame || !filt_frame) {
225         perror("Could not allocate frame");
226         exit(1);
227     }
228 
229     if ((ret = open_input_file(argv[1])) < 0)
230         goto end;
231     if ((ret = init_filters(filter_descr)) < 0)
232         goto end;
233 
234     /* read all packets */
235     while (1) {
236         if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
237             break;
238 
239         if (packet.stream_index == video_stream_index) {
240             ret = avcodec_send_packet(dec_ctx, &packet);
241             if (ret < 0) {
242                 av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
243                 break;
244             }
245 
246             while (ret >= 0) {
247                 ret = avcodec_receive_frame(dec_ctx, frame);
248                 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
249                     break;
250                 } else if (ret < 0) {
251                     av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
252                     goto end;
253                 }
254 
255                 frame->pts = frame->best_effort_timestamp;
256 
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");
260                     break;
261                 }
262 
263                 /* pull filtered frames from the filtergraph */
264                 while (1) {
265                     ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
266                     if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
267                         break;
268                     if (ret < 0)
269                         goto end;
270                     display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
271                     av_frame_unref(filt_frame);
272                 }
273                 av_frame_unref(frame);
274             }
275         }
276         av_packet_unref(&packet);
277     }
278 end:
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);
284 
285     if (ret < 0 && ret != AVERROR_EOF) {
286         fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
287         exit(1);
288     }
289 
290     exit(0);
291 }
292