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filtering_video.c
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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/avcodec.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";
42 
48 static int video_stream_index = -1;
49 static int64_t last_pts = AV_NOPTS_VALUE;
50 
51 static int open_input_file(const char *filename)
52 {
53  int ret;
54  AVCodec *dec;
55 
56  if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
57  av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
58  return ret;
59  }
60 
61  if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
62  av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
63  return ret;
64  }
65 
66  /* select the video stream */
67  ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
68  if (ret < 0) {
69  av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
70  return ret;
71  }
73  dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
74  av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
75 
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");
79  return ret;
80  }
81 
82  return 0;
83 }
84 
85 static int init_filters(const char *filters_descr)
86 {
87  char args[512];
88  int ret = 0;
89  AVFilter *buffersrc = avfilter_get_by_name("buffer");
90  AVFilter *buffersink = avfilter_get_by_name("buffersink");
93  AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
94  enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
95 
96  filter_graph = avfilter_graph_alloc();
97  if (!outputs || !inputs || !filter_graph) {
98  ret = AVERROR(ENOMEM);
99  goto end;
100  }
101 
102  /* buffer video source: the decoded frames from the decoder will be inserted here. */
103  snprintf(args, sizeof(args),
104  "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
105  dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
106  time_base.num, time_base.den,
107  dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
108 
109  ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
110  args, NULL, filter_graph);
111  if (ret < 0) {
112  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
113  goto end;
114  }
115 
116  /* buffer video sink: to terminate the filter chain. */
117  ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
118  NULL, NULL, filter_graph);
119  if (ret < 0) {
120  av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
121  goto end;
122  }
123 
124  ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
126  if (ret < 0) {
127  av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
128  goto end;
129  }
130 
131  /*
132  * Set the endpoints for the filter graph. The filter_graph will
133  * be linked to the graph described by filters_descr.
134  */
135 
136  /*
137  * The buffer source output must be connected to the input pad of
138  * the first filter described by filters_descr; since the first
139  * filter input label is not specified, it is set to "in" by
140  * default.
141  */
142  outputs->name = av_strdup("in");
143  outputs->filter_ctx = buffersrc_ctx;
144  outputs->pad_idx = 0;
145  outputs->next = NULL;
146 
147  /*
148  * The buffer sink input must be connected to the output pad of
149  * the last filter described by filters_descr; since the last
150  * filter output label is not specified, it is set to "out" by
151  * default.
152  */
153  inputs->name = av_strdup("out");
154  inputs->filter_ctx = buffersink_ctx;
155  inputs->pad_idx = 0;
156  inputs->next = NULL;
157 
158  if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
159  &inputs, &outputs, NULL)) < 0)
160  goto end;
161 
162  if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
163  goto end;
164 
165 end:
166  avfilter_inout_free(&inputs);
167  avfilter_inout_free(&outputs);
168 
169  return ret;
170 }
171 
172 static void display_frame(const AVFrame *frame, AVRational time_base)
173 {
174  int x, y;
175  uint8_t *p0, *p;
176  int64_t delay;
177 
178  if (frame->pts != AV_NOPTS_VALUE) {
179  if (last_pts != AV_NOPTS_VALUE) {
180  /* sleep roughly the right amount of time;
181  * usleep is in microseconds, just like AV_TIME_BASE. */
182  delay = av_rescale_q(frame->pts - last_pts,
183  time_base, AV_TIME_BASE_Q);
184  if (delay > 0 && delay < 1000000)
185  usleep(delay);
186  }
187  last_pts = frame->pts;
188  }
189 
190  /* Trivial ASCII grayscale display. */
191  p0 = frame->data[0];
192  puts("\033c");
193  for (y = 0; y < frame->height; y++) {
194  p = p0;
195  for (x = 0; x < frame->width; x++)
196  putchar(" .-+#"[*(p++) / 52]);
197  putchar('\n');
198  p0 += frame->linesize[0];
199  }
200  fflush(stdout);
201 }
202 
203 int main(int argc, char **argv)
204 {
205  int ret;
206  AVPacket packet;
208  AVFrame *filt_frame = av_frame_alloc();
209  int got_frame;
210 
211  if (!frame || !filt_frame) {
212  perror("Could not allocate frame");
213  exit(1);
214  }
215  if (argc != 2) {
216  fprintf(stderr, "Usage: %s file\n", argv[0]);
217  exit(1);
218  }
219 
220  av_register_all();
222 
223  if ((ret = open_input_file(argv[1])) < 0)
224  goto end;
225  if ((ret = init_filters(filter_descr)) < 0)
226  goto end;
227 
228  /* read all packets */
229  while (1) {
230  if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
231  break;
232 
233  if (packet.stream_index == video_stream_index) {
234  got_frame = 0;
235  ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
236  if (ret < 0) {
237  av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
238  break;
239  }
240 
241  if (got_frame) {
242  frame->pts = av_frame_get_best_effort_timestamp(frame);
243 
244  /* push the decoded frame into the filtergraph */
245  if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
246  av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
247  break;
248  }
249 
250  /* pull filtered frames from the filtergraph */
251  while (1) {
252  ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
253  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
254  break;
255  if (ret < 0)
256  goto end;
257  display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
258  av_frame_unref(filt_frame);
259  }
260  av_frame_unref(frame);
261  }
262  }
263  av_free_packet(&packet);
264  }
265 end:
266  avfilter_graph_free(&filter_graph);
267  avcodec_close(dec_ctx);
268  avformat_close_input(&fmt_ctx);
269  av_frame_free(&frame);
270  av_frame_free(&filt_frame);
271 
272  if (ret < 0 && ret != AVERROR_EOF) {
273  fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
274  exit(1);
275  }
276 
277  exit(0);
278 }
#define NULL
Definition: coverity.c:32
void av_free_packet(AVPacket *pkt)
Free a packet.
Definition: avpacket.c:280
This structure describes decoded (raw) audio or video data.
Definition: frame.h:171
AVFilterGraph * avfilter_graph_alloc(void)
Allocate a filter graph.
Definition: avfiltergraph.c:76
static const AVFilterPad outputs[]
Definition: af_ashowinfo.c:248
int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:402
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:184
struct AVFilterInOut * next
next input/input in the list, NULL if this is the last
Definition: avfilter.h:1362
#define av_opt_set_int_list(obj, name, val, term, flags)
Set a binary option to an integer list.
Definition: opt.h:748
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:1623
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:1444
AVCodec.
Definition: avcodec.h:3181
Format I/O context.
Definition: avformat.h:1272
memory buffer sink API for audio and video
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:641
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:135
AVOptions.
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:67
libavcodec/libavfilter gluing utilities
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:257
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1340
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.
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:94
#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:140
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:3496
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:2843
int width
width and height of the video frame
Definition: frame.h:220
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVFilterContext * buffersrc_ctx
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:2352
#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:148
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:491
static int video_stream_index
Libavcodec external API header.
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:861
const AVFilter * avfilter_get_by_name(const char *name)
Get a filter definition matching the given name.
Definition: avfilter.c:487
float y
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
Definition: opt.h:602
ret
Definition: avfilter.c:974
int width
picture width / height.
Definition: avcodec.h:1414
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
Keep a reference to the frame.
Definition: buffersrc.h:62
AVFilterContext * filter_ctx
filter context associated to this input/output
Definition: avfilter.h:1356
A linked-list of the inputs/outputs of the filter chain.
Definition: avfilter.h:1351
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:253
char * av_strdup(const char *s)
Duplicate the string s.
Definition: mem.c:265
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:199
AVFilterGraph * filter_graph
main external API structure.
Definition: avcodec.h:1241
Filter definition.
Definition: avfilter.h:470
static int open_input_file(const char *filename)
static const AVFilterPad inputs[]
Definition: af_ashowinfo.c:239
int pad_idx
index of the filt_ctx pad to use for linking
Definition: avfilter.h:1359
rational number numerator/denominator
Definition: rational.h:43
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
Definition: utils.c:1330
#define snprintf
Definition: snprintf.h:34
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1475
AVFilterContext * buffersink_ctx
char * name
unique name for this input/output in the list
Definition: avfilter.h:1353
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:462
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:182
static int init_filters(const char *filters_descr)
Main libavformat public API header.
Y , 8bpp.
Definition: pixfmt.h:71
AVFilterInOut * avfilter_inout_alloc(void)
Allocate a single AVFilterInOut entry.
Definition: graphparser.c:179
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3024
int den
denominator
Definition: rational.h:45
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
Definition: utils.c:3644
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:527
An instance of a filter.
Definition: avfilter.h:633
static void display_frame(const AVFrame *frame, AVRational time_base)
int height
Definition: frame.h:220
static AVFormatContext * fmt_ctx
int stream_index
Definition: avcodec.h:1164
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:884
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:121
AVPixelFormat
Pixel format.
Definition: pixfmt.h:61
This structure stores compressed data.
Definition: avcodec.h:1139
void av_register_all(void)
Initialize libavformat and register all the muxers, demuxers and protocols.
Definition: allformats.c:51
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:241