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>
35 #include <libavfilter/buffersink.h>
36 #include <libavfilter/buffersrc.h>
37 #include <libavutil/opt.h>
38 
39 const char *filter_descr = "scale=78:24,transpose=cclock";
40 /* other way:
41  scale=78:24 [scl]; [scl] transpose=cclock // assumes "[in]" and "[out]" to be input output pads respectively
42  */
43 
49 static int video_stream_index = -1;
50 static int64_t last_pts = AV_NOPTS_VALUE;
51 
52 static int open_input_file(const char *filename)
53 {
54  int ret;
55  AVCodec *dec;
56 
57  if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
58  av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
59  return ret;
60  }
61 
62  if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
63  av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
64  return ret;
65  }
66 
67  /* select the video stream */
68  ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
69  if (ret < 0) {
70  av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
71  return ret;
72  }
73  video_stream_index = ret;
74 
75  /* create decoding context */
76  dec_ctx = avcodec_alloc_context3(dec);
77  if (!dec_ctx)
78  return AVERROR(ENOMEM);
80  av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
81 
82  /* init the video decoder */
83  if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
84  av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
85  return ret;
86  }
87 
88  return 0;
89 }
90 
91 static int init_filters(const char *filters_descr)
92 {
93  char args[512];
94  int ret = 0;
95  const AVFilter *buffersrc = avfilter_get_by_name("buffer");
96  const AVFilter *buffersink = avfilter_get_by_name("buffersink");
99  AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
101 
102  filter_graph = avfilter_graph_alloc();
103  if (!outputs || !inputs || !filter_graph) {
104  ret = AVERROR(ENOMEM);
105  goto end;
106  }
107 
108  /* buffer video source: the decoded frames from the decoder will be inserted here. */
109  snprintf(args, sizeof(args),
110  "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
111  dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
112  time_base.num, time_base.den,
113  dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
114 
115  ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
116  args, NULL, filter_graph);
117  if (ret < 0) {
118  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
119  goto end;
120  }
121 
122  /* buffer video sink: to terminate the filter chain. */
123  ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
124  NULL, NULL, filter_graph);
125  if (ret < 0) {
126  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
127  goto end;
128  }
129 
130  ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
132  if (ret < 0) {
133  av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
134  goto end;
135  }
136 
137  /*
138  * Set the endpoints for the filter graph. The filter_graph will
139  * be linked to the graph described by filters_descr.
140  */
141 
142  /*
143  * The buffer source output must be connected to the input pad of
144  * the first filter described by filters_descr; since the first
145  * filter input label is not specified, it is set to "in" by
146  * default.
147  */
148  outputs->name = av_strdup("in");
149  outputs->filter_ctx = buffersrc_ctx;
150  outputs->pad_idx = 0;
151  outputs->next = NULL;
152 
153  /*
154  * The buffer sink input must be connected to the output pad of
155  * the last filter described by filters_descr; since the last
156  * filter output label is not specified, it is set to "out" by
157  * default.
158  */
159  inputs->name = av_strdup("out");
160  inputs->filter_ctx = buffersink_ctx;
161  inputs->pad_idx = 0;
162  inputs->next = NULL;
163 
164  if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
165  &inputs, &outputs, NULL)) < 0)
166  goto end;
167 
168  if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
169  goto end;
170 
171 end:
172  avfilter_inout_free(&inputs);
173  avfilter_inout_free(&outputs);
174 
175  return ret;
176 }
177 
178 static void display_frame(const AVFrame *frame, AVRational time_base)
179 {
180  int x, y;
181  uint8_t *p0, *p;
182  int64_t delay;
183 
184  if (frame->pts != AV_NOPTS_VALUE) {
185  if (last_pts != AV_NOPTS_VALUE) {
186  /* sleep roughly the right amount of time;
187  * usleep is in microseconds, just like AV_TIME_BASE. */
188  delay = av_rescale_q(frame->pts - last_pts,
189  time_base, AV_TIME_BASE_Q);
190  if (delay > 0 && delay < 1000000)
191  usleep(delay);
192  }
193  last_pts = frame->pts;
194  }
195 
196  /* Trivial ASCII grayscale display. */
197  p0 = frame->data[0];
198  puts("\033c");
199  for (y = 0; y < frame->height; y++) {
200  p = p0;
201  for (x = 0; x < frame->width; x++)
202  putchar(" .-+#"[*(p++) / 52]);
203  putchar('\n');
204  p0 += frame->linesize[0];
205  }
206  fflush(stdout);
207 }
208 
209 int main(int argc, char **argv)
210 {
211  int ret;
212  AVPacket packet;
214  AVFrame *filt_frame = av_frame_alloc();
215 
216  if (!frame || !filt_frame) {
217  perror("Could not allocate frame");
218  exit(1);
219  }
220  if (argc != 2) {
221  fprintf(stderr, "Usage: %s file\n", argv[0]);
222  exit(1);
223  }
224 
225  av_register_all();
227 
228  if ((ret = open_input_file(argv[1])) < 0)
229  goto end;
230  if ((ret = init_filters(filter_descr)) < 0)
231  goto end;
232 
233  /* read all packets */
234  while (1) {
235  if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
236  break;
237 
238  if (packet.stream_index == video_stream_index) {
239  ret = avcodec_send_packet(dec_ctx, &packet);
240  if (ret < 0) {
241  av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
242  break;
243  }
244 
245  while (ret >= 0) {
246  ret = avcodec_receive_frame(dec_ctx, frame);
247  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
248  break;
249  } else if (ret < 0) {
250  av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
251  goto end;
252  }
253 
254  if (ret >= 0) {
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  }
277  av_packet_unref(&packet);
278  }
279 end:
280  avfilter_graph_free(&filter_graph);
281  avcodec_free_context(&dec_ctx);
282  avformat_close_input(&fmt_ctx);
283  av_frame_free(&frame);
284  av_frame_free(&filt_frame);
285 
286  if (ret < 0 && ret != AVERROR_EOF) {
287  fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
288  exit(1);
289  }
290 
291  exit(0);
292 }
#define NULL
Definition: coverity.c:32
This structure describes decoded (raw) audio or video data.
Definition: frame.h:201
AVFilterGraph * avfilter_graph_alloc(void)
Allocate a filter graph.
Definition: avfiltergraph.c:83
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:203
struct AVFilterInOut * next
next input/input in the list, NULL if this is the last
Definition: avfilter.h:977
#define av_opt_set_int_list(obj, name, val, term, flags)
Set a binary option to an integer list.
Definition: opt.h:706
const char * filter_descr
int num
Numerator.
Definition: rational.h:59
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:1866
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:1697
AVCodec.
Definition: avcodec.h:3351
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:346
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:150
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:294
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1393
int avcodec_parameters_to_context(AVCodecContext *codec, const AVCodecParameters *par)
Fill the codec context based on the values from the supplied codec parameters.
Definition: utils.c:2306
void avfilter_register_all(void)
Initialize the filter system.
Definition: allfilters.c:416
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
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:4115
int width
Definition: frame.h:259
#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:163
int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Return decoded output data from a decoder.
Definition: decode.c:709
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:558
static int video_stream_index
Keep a reference to the frame.
Definition: buffersrc.h:53
const AVFilter * avfilter_get_by_name(const char *name)
Get a filter definition matching the given name.
Definition: avfilter.c:579
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
Definition: options.c:157
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
Definition: opt.h:554
int width
picture width / height.
Definition: avcodec.h:1660
#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 inputs[]
Definition: af_acontrast.c:193
AVFilterContext * filter_ctx
filter context associated to this input/output
Definition: avfilter.h:971
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
A linked-list of the inputs/outputs of the filter chain.
Definition: avfilter.h:966
int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt)
Supply raw packet data as input to a decoder.
Definition: decode.c:642
char * av_strdup(const char *s)
Duplicate a string.
Definition: mem.c:251
Libavcodec external API header.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer...
Definition: options.c:172
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:260
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:232
AVFilterGraph * filter_graph
main external API structure.
Definition: avcodec.h:1488
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:590
Filter definition.
Definition: avfilter.h:144
static int open_input_file(const char *filename)
int pad_idx
index of the filt_ctx pad to use for linking
Definition: avfilter.h:974
Rational number (pair of numerator and denominator).
Definition: rational.h:58
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
Definition: utils.c:614
#define snprintf
Definition: snprintf.h:34
int64_t best_effort_timestamp
frame timestamp estimated using various heuristics, in stream time base
Definition: frame.h:466
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1712
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:266
AVFilterContext * buffersink_ctx
char * name
unique name for this input/output in the list
Definition: avfilter.h:968
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:510
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:215
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:198
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3497
int den
Denominator.
Definition: rational.h:60
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:4350
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:515
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:538
An instance of a filter.
Definition: avfilter.h:338
static void display_frame(const AVFrame *frame, AVRational time_base)
int height
Definition: frame.h:259
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1014
static AVFormatContext * fmt_ctx
int stream_index
Definition: avcodec.h:1402
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:901
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:67
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60
This structure stores compressed data.
Definition: avcodec.h:1377
void av_register_all(void)
Initialize libavformat and register all the muxers, demuxers and protocols.
Definition: allformats.c:395
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248