FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
filtering_video.c
Go to the documentation of this file.
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 
33 #include <libavcodec/avcodec.h>
34 #include <libavformat/avformat.h>
36 #include <libavfilter/buffersink.h>
37 #include <libavfilter/buffersrc.h>
38 #include <libavutil/opt.h>
39 
40 const char *filter_descr = "scale=78:24,transpose=cclock";
41 /* other way:
42  scale=78:24 [scl]; [scl] transpose=cclock // assumes "[in]" and "[out]" to be input output pads respectively
43  */
44 
50 static int video_stream_index = -1;
51 static int64_t last_pts = AV_NOPTS_VALUE;
52 
53 static int open_input_file(const char *filename)
54 {
55  int ret;
56  AVCodec *dec;
57 
58  if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
59  av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
60  return ret;
61  }
62 
63  if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
64  av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
65  return ret;
66  }
67 
68  /* select the video stream */
69  ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
70  if (ret < 0) {
71  av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
72  return ret;
73  }
74  video_stream_index = ret;
75  dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
76  av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
77 
78  /* init the video decoder */
79  if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
80  av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
81  return ret;
82  }
83 
84  return 0;
85 }
86 
87 static int init_filters(const char *filters_descr)
88 {
89  char args[512];
90  int ret = 0;
91  AVFilter *buffersrc = avfilter_get_by_name("buffer");
92  AVFilter *buffersink = avfilter_get_by_name("buffersink");
95  AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
97 
98  filter_graph = avfilter_graph_alloc();
99  if (!outputs || !inputs || !filter_graph) {
100  ret = AVERROR(ENOMEM);
101  goto end;
102  }
103 
104  /* buffer video source: the decoded frames from the decoder will be inserted here. */
105  snprintf(args, sizeof(args),
106  "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
107  dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
108  time_base.num, time_base.den,
109  dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
110 
111  ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
112  args, NULL, filter_graph);
113  if (ret < 0) {
114  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
115  goto end;
116  }
117 
118  /* buffer video sink: to terminate the filter chain. */
119  ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
120  NULL, NULL, filter_graph);
121  if (ret < 0) {
122  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
123  goto end;
124  }
125 
126  ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
128  if (ret < 0) {
129  av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
130  goto end;
131  }
132 
133  /*
134  * Set the endpoints for the filter graph. The filter_graph will
135  * be linked to the graph described by filters_descr.
136  */
137 
138  /*
139  * The buffer source output must be connected to the input pad of
140  * the first filter described by filters_descr; since the first
141  * filter input label is not specified, it is set to "in" by
142  * default.
143  */
144  outputs->name = av_strdup("in");
145  outputs->filter_ctx = buffersrc_ctx;
146  outputs->pad_idx = 0;
147  outputs->next = NULL;
148 
149  /*
150  * The buffer sink input must be connected to the output pad of
151  * the last filter described by filters_descr; since the last
152  * filter output label is not specified, it is set to "out" by
153  * default.
154  */
155  inputs->name = av_strdup("out");
156  inputs->filter_ctx = buffersink_ctx;
157  inputs->pad_idx = 0;
158  inputs->next = NULL;
159 
160  if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
161  &inputs, &outputs, NULL)) < 0)
162  goto end;
163 
164  if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
165  goto end;
166 
167 end:
168  avfilter_inout_free(&inputs);
169  avfilter_inout_free(&outputs);
170 
171  return ret;
172 }
173 
174 static void display_frame(const AVFrame *frame, AVRational time_base)
175 {
176  int x, y;
177  uint8_t *p0, *p;
178  int64_t delay;
179 
180  if (frame->pts != AV_NOPTS_VALUE) {
181  if (last_pts != AV_NOPTS_VALUE) {
182  /* sleep roughly the right amount of time;
183  * usleep is in microseconds, just like AV_TIME_BASE. */
184  delay = av_rescale_q(frame->pts - last_pts,
185  time_base, AV_TIME_BASE_Q);
186  if (delay > 0 && delay < 1000000)
187  usleep(delay);
188  }
189  last_pts = frame->pts;
190  }
191 
192  /* Trivial ASCII grayscale display. */
193  p0 = frame->data[0];
194  puts("\033c");
195  for (y = 0; y < frame->height; y++) {
196  p = p0;
197  for (x = 0; x < frame->width; x++)
198  putchar(" .-+#"[*(p++) / 52]);
199  putchar('\n');
200  p0 += frame->linesize[0];
201  }
202  fflush(stdout);
203 }
204 
205 int main(int argc, char **argv)
206 {
207  int ret;
208  AVPacket packet;
210  AVFrame *filt_frame = av_frame_alloc();
211  int got_frame;
212 
213  if (!frame || !filt_frame) {
214  perror("Could not allocate frame");
215  exit(1);
216  }
217  if (argc != 2) {
218  fprintf(stderr, "Usage: %s file\n", argv[0]);
219  exit(1);
220  }
221 
222  av_register_all();
224 
225  if ((ret = open_input_file(argv[1])) < 0)
226  goto end;
227  if ((ret = init_filters(filter_descr)) < 0)
228  goto end;
229 
230  /* read all packets */
231  while (1) {
232  if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
233  break;
234 
235  if (packet.stream_index == video_stream_index) {
236  got_frame = 0;
237  ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
238  if (ret < 0) {
239  av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
240  break;
241  }
242 
243  if (got_frame) {
244  frame->pts = av_frame_get_best_effort_timestamp(frame);
245 
246  /* push the decoded frame into the filtergraph */
247  if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
248  av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
249  break;
250  }
251 
252  /* pull filtered frames from the filtergraph */
253  while (1) {
254  ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
255  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
256  break;
257  if (ret < 0)
258  goto end;
259  display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
260  av_frame_unref(filt_frame);
261  }
262  av_frame_unref(frame);
263  }
264  }
265  av_packet_unref(&packet);
266  }
267 end:
268  avfilter_graph_free(&filter_graph);
269  avcodec_close(dec_ctx);
270  avformat_close_input(&fmt_ctx);
271  av_frame_free(&frame);
272  av_frame_free(&filt_frame);
273 
274  if (ret < 0 && ret != AVERROR_EOF) {
275  fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
276  exit(1);
277  }
278 
279  exit(0);
280 }
#define NULL
Definition: coverity.c:32
This structure describes decoded (raw) audio or video data.
Definition: frame.h:184
AVFilterGraph * avfilter_graph_alloc(void)
Allocate a filter graph.
Definition: avfiltergraph.c:76
Memory buffer source API.
int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx)
Check validity and configure all the links and formats in the graph.
void avfilter_inout_free(AVFilterInOut **inout)
Free the supplied list of AVFilterInOut and set *inout to NULL.
Definition: graphparser.c:187
struct AVFilterInOut * next
next input/input in the list, NULL if this is the last
Definition: avfilter.h:963
#define av_opt_set_int_list(obj, name, val, term, flags)
Set a binary option to an integer list.
Definition: opt.h:708
const char * filter_descr
int num
numerator
Definition: rational.h:44
AVRational sample_aspect_ratio
sample aspect ratio (0 if unknown) That is the width of a pixel divided by the height of the pixel...
Definition: avcodec.h:2068
void avfilter_graph_free(AVFilterGraph **graph)
Free a graph, destroy its links, and set *graph to NULL.
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1885
AVCodec.
Definition: avcodec.h:3559
Format I/O context.
Definition: avformat.h:1325
memory buffer sink API for audio and video
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:313
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:140
AVOptions.
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
static int64_t last_pts
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:268
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1393
void avfilter_register_all(void)
Initialize the filter system.
Definition: allfilters.c:40
static AVFrame * frame
int avfilter_graph_create_filter(AVFilterContext **filt_ctx, const AVFilter *filt, const char *name, const char *args, void *opaque, AVFilterGraph *graph_ctx)
Create and add a filter instance into an existing graph.
#define AVERROR_EOF
End of file.
Definition: error.h:55
int64_t av_frame_get_best_effort_timestamp(const AVFrame *frame)
Accessors for some AVFrame fields.
int main(int argc, char **argv)
#define av_log(a,...)
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
int av_find_best_stream(AVFormatContext *ic, enum AVMediaType type, int wanted_stream_nb, int related_stream, AVCodec **decoder_ret, int flags)
Find the "best" stream in the file.
Definition: utils.c:3872
int avcodec_close(AVCodecContext *avctx)
Close a given AVCodecContext and free all the data associated with it (but not the AVCodecContext its...
Definition: utils.c:2959
int width
width and height of the video frame
Definition: frame.h:236
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVFilterContext * buffersrc_ctx
#define AVERROR(e)
Definition: error.h:43
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:153
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:539
static int video_stream_index
const AVFilter * avfilter_get_by_name(const char *name)
Get a filter definition matching the given name.
Definition: avfilter.c:519
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
Definition: opt.h:556
int width
picture width / height.
Definition: avcodec.h:1844
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
static const AVFilterPad outputs[]
Definition: af_afftfilt.c:386
AVFilterContext * filter_ctx
filter context associated to this input/output
Definition: avfilter.h:957
A linked-list of the inputs/outputs of the filter chain.
Definition: avfilter.h:952
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:376
Libavcodec external API header.
attribute_deprecated int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture, int *got_picture_ptr, const AVPacket *avpkt)
Decode the video frame of size avpkt->size from avpkt->data into picture.
Definition: utils.c:2180
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:256
char * av_strdup(const char *s)
Duplicate the string s.
Definition: mem.c:267
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:215
AVFilterGraph * filter_graph
main external API structure.
Definition: avcodec.h:1657
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:563
Filter definition.
Definition: avfilter.h:142
static int open_input_file(const char *filename)
int pad_idx
index of the filt_ctx pad to use for linking
Definition: avfilter.h:960
rational number numerator/denominator
Definition: rational.h:43
Keep a reference to the frame.
Definition: buffersrc.h:54
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
Definition: utils.c:1208
#define snprintf
Definition: snprintf.h:34
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1640
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:262
AVFilterContext * buffersink_ctx
char * name
unique name for this input/output in the list
Definition: avfilter.h:954
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:484
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:198
static int init_filters(const char *filters_descr)
Main libavformat public API header.
Y , 8bpp.
Definition: pixfmt.h:70
AVFilterInOut * avfilter_inout_alloc(void)
Allocate a single AVFilterInOut entry.
Definition: graphparser.c:182
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3277
int den
denominator
Definition: rational.h:45
int attribute_align_arg av_buffersrc_add_frame_flags(AVFilterContext *ctx, AVFrame *frame, int flags)
Add a frame to the buffer source.
Definition: buffersrc.c:152
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
Definition: utils.c:4103
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:471
int avfilter_graph_parse_ptr(AVFilterGraph *graph, const char *filters, AVFilterInOut **inputs, AVFilterInOut **outputs, void *log_ctx)
Add a graph described by a string to a graph.
Definition: graphparser.c:522
An instance of a filter.
Definition: avfilter.h:305
static void display_frame(const AVFrame *frame, AVRational time_base)
int height
Definition: frame.h:236
static AVFormatContext * fmt_ctx
int stream_index
Definition: avcodec.h:1590
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:913
static AVCodecContext * dec_ctx
int attribute_align_arg av_buffersink_get_frame(AVFilterContext *ctx, AVFrame *frame)
Get a frame with filtered data from sink and put it in frame.
Definition: buffersink.c:123
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60
This structure stores compressed data.
Definition: avcodec.h:1565
void av_register_all(void)
Initialize libavformat and register all the muxers, demuxers and protocols.
Definition: allformats.c:44
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:244