FFmpeg
vf_blackdetect.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2012 Stefano Sabatini
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Video black detector, loosely based on blackframe with extended
24  * syntax and features
25  */
26 
27 #include <float.h>
28 #include "libavutil/opt.h"
29 #include "libavutil/pixdesc.h"
30 #include "libavutil/timestamp.h"
31 #include "avfilter.h"
32 #include "internal.h"
33 
34 typedef struct BlackDetectContext {
35  const AVClass *class;
36  double black_min_duration_time; ///< minimum duration of detected black, in seconds
37  int64_t black_min_duration; ///< minimum duration of detected black, expressed in timebase units
38  int64_t black_start; ///< pts start time of the first black picture
39  int64_t black_end; ///< pts end time of the last black picture
40  int64_t last_picref_pts; ///< pts of the last input picture
42 
45  unsigned int pixel_black_th_i;
46 
47  unsigned int nb_black_pixels; ///< number of black pixels counted so far
49  int depth;
51  unsigned int *counter;
53 
54 #define OFFSET(x) offsetof(BlackDetectContext, x)
55 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
56 
57 static const AVOption blackdetect_options[] = {
58  { "d", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX, FLAGS },
59  { "black_min_duration", "set minimum detected black duration in seconds", OFFSET(black_min_duration_time), AV_OPT_TYPE_DOUBLE, {.dbl=2}, 0, DBL_MAX, FLAGS },
60  { "picture_black_ratio_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1, FLAGS },
61  { "pic_th", "set the picture black ratio threshold", OFFSET(picture_black_ratio_th), AV_OPT_TYPE_DOUBLE, {.dbl=.98}, 0, 1, FLAGS },
62  { "pixel_black_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1, FLAGS },
63  { "pix_th", "set the pixel black threshold", OFFSET(pixel_black_th), AV_OPT_TYPE_DOUBLE, {.dbl=.10}, 0, 1, FLAGS },
64  { NULL }
65 };
66 
67 AVFILTER_DEFINE_CLASS(blackdetect);
68 
69 #define YUVJ_FORMATS \
70  AV_PIX_FMT_YUVJ411P, AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P
71 
72 static const enum AVPixelFormat yuvj_formats[] = {
74 };
75 
77 {
78  static const enum AVPixelFormat pix_fmts[] = {
99  };
100 
101  AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
102  if (!fmts_list)
103  return AVERROR(ENOMEM);
104  return ff_set_common_formats(ctx, fmts_list);
105 }
106 
108 {
109  AVFilterContext *ctx = inlink->dst;
110  BlackDetectContext *s = ctx->priv;
112  const int depth = desc->comp[0].depth;
113  const int max = (1 << depth) - 1;
114  const int factor = (1 << (depth - 8));
115 
116  s->depth = depth;
118  s->time_base = inlink->time_base;
120  s->counter = av_calloc(s->nb_threads, sizeof(*s->counter));
121  if (!s->counter)
122  return AVERROR(ENOMEM);
123 
125  // luminance_minimum_value + pixel_black_th * luminance_range_size
126  s->pixel_black_th * max :
127  16 * factor + s->pixel_black_th * (235 - 16) * factor;
128 
130  "black_min_duration:%s pixel_black_th:%f pixel_black_th_i:%d picture_black_ratio_th:%f\n",
134  return 0;
135 }
136 
138 {
139  BlackDetectContext *s = ctx->priv;
140 
141  if ((s->black_end - s->black_start) >= s->black_min_duration) {
142  av_log(s, AV_LOG_INFO,
143  "black_start:%s black_end:%s black_duration:%s\n",
147  }
148 }
149 
151  int jobnr, int nb_jobs)
152 {
153  BlackDetectContext *s = ctx->priv;
154  const unsigned int threshold = s->pixel_black_th_i;
155  unsigned int *counterp = &s->counter[jobnr];
156  AVFrame *in = arg;
157  const int linesize = in->linesize[0];
158  const int w = in->width;
159  const int h = in->height;
160  const int start = (h * jobnr) / nb_jobs;
161  const int end = (h * (jobnr+1)) / nb_jobs;
162  const int size = end - start;
163  unsigned int counter = 0;
164 
165  if (s->depth == 8) {
166  const uint8_t *p = in->data[0] + start * linesize;
167 
168  for (int i = 0; i < size; i++) {
169  for (int x = 0; x < w; x++)
170  counter += p[x] <= threshold;
171  p += linesize;
172  }
173  } else {
174  const uint16_t *p = (const uint16_t *)(in->data[0] + start * linesize);
175 
176  for (int i = 0; i < size; i++) {
177  for (int x = 0; x < w; x++)
178  counter += p[x] <= threshold;
179  p += linesize / 2;
180  }
181  }
182 
183  *counterp = counter;
184 
185  return 0;
186 }
187 
189 {
190  AVFilterContext *ctx = inlink->dst;
191  BlackDetectContext *s = ctx->priv;
192  double picture_black_ratio = 0;
193 
194  ctx->internal->execute(ctx, black_counter, picref, NULL,
195  FFMIN(inlink->h, s->nb_threads));
196 
197  for (int i = 0; i < s->nb_threads; i++)
198  s->nb_black_pixels += s->counter[i];
199 
200  picture_black_ratio = (double)s->nb_black_pixels / (inlink->w * inlink->h);
201 
202  av_log(ctx, AV_LOG_DEBUG,
203  "frame:%"PRId64" picture_black_ratio:%f pts:%s t:%s type:%c\n",
204  inlink->frame_count_out, picture_black_ratio,
205  av_ts2str(picref->pts), av_ts2timestr(picref->pts, &s->time_base),
207 
208  if (picture_black_ratio >= s->picture_black_ratio_th) {
209  if (!s->black_started) {
210  /* black starts here */
211  s->black_started = 1;
212  s->black_start = picref->pts;
213  av_dict_set(&picref->metadata, "lavfi.black_start",
214  av_ts2timestr(s->black_start, &s->time_base), 0);
215  }
216  } else if (s->black_started) {
217  /* black ends here */
218  s->black_started = 0;
219  s->black_end = picref->pts;
220  check_black_end(ctx);
221  av_dict_set(&picref->metadata, "lavfi.black_end",
222  av_ts2timestr(s->black_end, &s->time_base), 0);
223  }
224 
225  s->last_picref_pts = picref->pts;
226  s->nb_black_pixels = 0;
227  return ff_filter_frame(inlink->dst->outputs[0], picref);
228 }
229 
231 {
232  BlackDetectContext *s = ctx->priv;
233 
234  av_freep(&s->counter);
235 
236  if (s->black_started) {
237  // FIXME: black_end should be set to last_picref_pts + last_picref_duration
238  s->black_end = s->last_picref_pts;
239  check_black_end(ctx);
240  }
241 }
242 
243 static const AVFilterPad blackdetect_inputs[] = {
244  {
245  .name = "default",
246  .type = AVMEDIA_TYPE_VIDEO,
247  .config_props = config_input,
248  .filter_frame = filter_frame,
249  },
250  { NULL }
251 };
252 
254  {
255  .name = "default",
256  .type = AVMEDIA_TYPE_VIDEO,
257  },
258  { NULL }
259 };
260 
262  .name = "blackdetect",
263  .description = NULL_IF_CONFIG_SMALL("Detect video intervals that are (almost) black."),
264  .priv_size = sizeof(BlackDetectContext),
266  .inputs = blackdetect_inputs,
267  .outputs = blackdetect_outputs,
268  .uninit = uninit,
269  .priv_class = &blackdetect_class,
271 };
#define NULL
Definition: coverity.c:32
#define AV_PIX_FMT_YUVA422P16
Definition: pixfmt.h:442
static int black_counter(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
#define AV_PIX_FMT_YUV440P10
Definition: pixfmt.h:401
#define AV_PIX_FMT_YUVA422P9
Definition: pixfmt.h:434
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2573
This structure describes decoded (raw) audio or video data.
Definition: frame.h:314
AVOption.
Definition: opt.h:248
#define AV_PIX_FMT_YUVA420P10
Definition: pixfmt.h:436
#define AV_PIX_FMT_YUV444P14
Definition: pixfmt.h:409
#define AV_PIX_FMT_YUVA422P10
Definition: pixfmt.h:437
const char * desc
Definition: libsvtav1.c:79
planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples)
Definition: pixfmt.h:71
Main libavfilter public API header.
#define AV_PIX_FMT_YUV420P12
Definition: pixfmt.h:403
AVRational time_base
AVFilter ff_vf_blackdetect
void * av_calloc(size_t nmemb, size_t size)
Non-inlined equivalent of av_mallocz_array().
Definition: mem.c:245
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:287
#define AV_PIX_FMT_GRAY10
Definition: pixfmt.h:380
unsigned int nb_black_pixels
number of black pixels counted so far
const char * name
Pad name.
Definition: internal.h:60
#define AV_PIX_FMT_GRAY12
Definition: pixfmt.h:381
static const AVFilterPad blackdetect_inputs[]
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1094
planar YUV 4:2:0, 20bpp, (1 Cr & Cb sample per 2x2 Y & A samples)
Definition: pixfmt.h:101
AVComponentDescriptor comp[4]
Parameters that describe how pixels are packed.
Definition: pixdesc.h:117
uint8_t
#define av_cold
Definition: attributes.h:88
static av_cold void uninit(AVFilterContext *ctx)
AVOptions.
static int config_input(AVFilterLink *inlink)
timestamp utils, mostly useful for debugging/logging purposes
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:407
#define AV_PIX_FMT_YUVA420P9
Definition: pixfmt.h:433
static int query_formats(AVFilterContext *ctx)
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
char av_get_picture_type_char(enum AVPictureType pict_type)
Return a single letter to describe the given picture type pict_type.
Definition: utils.c:88
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:210
AVDictionary * metadata
metadata.
Definition: frame.h:600
#define AV_PIX_FMT_YUV444P16
Definition: pixfmt.h:412
#define max(a, b)
Definition: cuda_runtime.h:33
ptrdiff_t size
Definition: opengl_enc.c:100
#define AV_PIX_FMT_YUV422P12
Definition: pixfmt.h:404
#define AV_PIX_FMT_YUVA420P16
Definition: pixfmt.h:441
int ff_fmt_is_in(int fmt, const int *fmts)
Tell if an integer is contained in the provided -1-terminated list of integers.
Definition: formats.c:258
#define av_log(a,...)
int64_t black_min_duration
minimum duration of detected black, expressed in timebase units
double picture_black_ratio_th
A filter pad used for either input or output.
Definition: internal.h:54
planar YUV 4:2:2 24bpp, (1 Cr & Cb sample per 2x1 Y & A samples)
Definition: pixfmt.h:176
int width
Definition: frame.h:372
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:588
#define av_ts2timestr(ts, tb)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: timestamp.h:76
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:115
void * priv
private data for use by the filter
Definition: avfilter.h:356
#define AVFILTER_FLAG_SLICE_THREADS
The filter supports multithreading by splitting frames into multiple parts and processing them concur...
Definition: avfilter.h:117
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:215
#define AV_PIX_FMT_YUVA444P16
Definition: pixfmt.h:443
const char * arg
Definition: jacosubdec.c:66
planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 plane for the UV components, which are interleaved (firs...
Definition: pixfmt.h:89
#define AV_PIX_FMT_YUV444P10
Definition: pixfmt.h:402
#define OFFSET(x)
planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Definition: pixfmt.h:70
static const AVFilterPad blackdetect_outputs[]
#define AV_PIX_FMT_YUV422P9
Definition: pixfmt.h:397
as above, but U and V bytes are swapped
Definition: pixfmt.h:90
enum AVPictureType pict_type
Picture type of the frame.
Definition: frame.h:397
int ff_filter_get_nb_threads(AVFilterContext *ctx)
Get number of threads for current filter instance.
Definition: avfilter.c:802
#define AV_PIX_FMT_GRAY16
Definition: pixfmt.h:383
double black_min_duration_time
minimum duration of detected black, in seconds
#define FFMIN(a, b)
Definition: common.h:105
int64_t last_picref_pts
pts of the last input picture
#define AV_PIX_FMT_YUVA444P12
Definition: pixfmt.h:440
#define FLAGS
uint8_t w
Definition: llviddspenc.c:39
AVFormatContext * ctx
Definition: movenc.c:48
#define s(width, name)
Definition: cbs_vp9.c:257
unsigned int pixel_black_th_i
#define AV_PIX_FMT_YUVA444P10
Definition: pixfmt.h:438
AVFILTER_DEFINE_CLASS(blackdetect)
#define AV_PIX_FMT_YUV444P9
Definition: pixfmt.h:398
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
static void check_black_end(AVFilterContext *ctx)
#define AV_PIX_FMT_YUV420P16
Definition: pixfmt.h:410
#define AV_LOG_INFO
Standard information.
Definition: log.h:205
#define AV_PIX_FMT_YUV420P14
Definition: pixfmt.h:407
static enum AVPixelFormat yuvj_formats[]
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:345
planar YUV 4:4:4 32bpp, (1 Cr & Cb sample per 1x1 Y & A samples)
Definition: pixfmt.h:177
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
#define AV_PIX_FMT_GRAY14
Definition: pixfmt.h:382
#define YUVJ_FORMATS
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
uint8_t pi<< 24) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_U8, uint8_t,(*(const uint8_t *) pi-0x80)*(1.0f/(1<< 7))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_U8, uint8_t,(*(const uint8_t *) pi-0x80)*(1.0/(1<< 7))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_S16, int16_t,(*(const int16_t *) pi >> 8)+0x80) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_S16, int16_t,*(const int16_t *) pi *(1.0f/(1<< 15))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_S16, int16_t,*(const int16_t *) pi *(1.0/(1<< 15))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_S32, int32_t,(*(const int32_t *) pi >> 24)+0x80) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_S32, int32_t,*(const int32_t *) pi *(1.0f/(1U<< 31))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_S32, int32_t,*(const int32_t *) pi *(1.0/(1U<< 31))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_FLT, float, av_clip_uint8(lrintf(*(const float *) pi *(1<< 7))+0x80)) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S16, int16_t, AV_SAMPLE_FMT_FLT, float, av_clip_int16(lrintf(*(const float *) pi *(1<< 15)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S32, int32_t, AV_SAMPLE_FMT_FLT, float, av_clipl_int32(llrintf(*(const float *) pi *(1U<< 31)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_DBL, double, av_clip_uint8(lrint(*(const double *) pi *(1<< 7))+0x80)) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S16, int16_t, AV_SAMPLE_FMT_DBL, double, av_clip_int16(lrint(*(const double *) pi *(1<< 15)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S32, int32_t, AV_SAMPLE_FMT_DBL, double, av_clipl_int32(llrint(*(const double *) pi *(1U<< 31))))#define SET_CONV_FUNC_GROUP(ofmt, ifmt) static void set_generic_function(AudioConvert *ac){}void ff_audio_convert_free(AudioConvert **ac){if(!*ac) return;ff_dither_free(&(*ac) ->dc);av_freep(ac);}AudioConvert *ff_audio_convert_alloc(AVAudioResampleContext *avr, enum AVSampleFormat out_fmt, enum AVSampleFormat in_fmt, int channels, int sample_rate, int apply_map){AudioConvert *ac;int in_planar, out_planar;ac=av_mallocz(sizeof(*ac));if(!ac) return NULL;ac->avr=avr;ac->out_fmt=out_fmt;ac->in_fmt=in_fmt;ac->channels=channels;ac->apply_map=apply_map;if(avr->dither_method!=AV_RESAMPLE_DITHER_NONE &&av_get_packed_sample_fmt(out_fmt)==AV_SAMPLE_FMT_S16 &&av_get_bytes_per_sample(in_fmt) > 2){ac->dc=ff_dither_alloc(avr, out_fmt, in_fmt, channels, sample_rate, apply_map);if(!ac->dc){av_free(ac);return NULL;}return ac;}in_planar=ff_sample_fmt_is_planar(in_fmt, channels);out_planar=ff_sample_fmt_is_planar(out_fmt, channels);if(in_planar==out_planar){ac->func_type=CONV_FUNC_TYPE_FLAT;ac->planes=in_planar?ac->channels:1;}else if(in_planar) ac->func_type=CONV_FUNC_TYPE_INTERLEAVE;else ac->func_type=CONV_FUNC_TYPE_DEINTERLEAVE;set_generic_function(ac);if(ARCH_AARCH64) ff_audio_convert_init_aarch64(ac);if(ARCH_ARM) ff_audio_convert_init_arm(ac);if(ARCH_X86) ff_audio_convert_init_x86(ac);return ac;}int ff_audio_convert(AudioConvert *ac, AudioData *out, AudioData *in){int use_generic=1;int len=in->nb_samples;int p;if(ac->dc){av_log(ac->avr, AV_LOG_TRACE,"%d samples - audio_convert: %s to %s (dithered)\n", len, av_get_sample_fmt_name(ac->in_fmt), av_get_sample_fmt_name(ac->out_fmt));return ff_convert_dither(ac-> in
#define AV_PIX_FMT_YUV420P10
Definition: pixfmt.h:399
planar YUV 4:1:0, 9bpp, (1 Cr & Cb sample per 4x4 Y samples)
Definition: pixfmt.h:72
int64_t black_end
pts end time of the last black picture
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:145
Rational number (pair of numerator and denominator).
Definition: rational.h:58
static const int factor[16]
Definition: vf_pp7.c:77
const char * name
Filter name.
Definition: avfilter.h:149
#define AV_PIX_FMT_YUV440P12
Definition: pixfmt.h:405
#define AV_PIX_FMT_YUV420P9
Definition: pixfmt.h:396
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:353
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:303
#define AV_PIX_FMT_YUV422P14
Definition: pixfmt.h:408
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVFilterInternal * internal
An opaque struct for libavfilter internal use.
Definition: avfilter.h:381
#define AV_PIX_FMT_YUV422P10
Definition: pixfmt.h:400
#define AV_PIX_FMT_YUV444P12
Definition: pixfmt.h:406
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:328
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
Y , 8bpp.
Definition: pixfmt.h:74
#define AV_PIX_FMT_YUVA444P9
Definition: pixfmt.h:435
planar YUV 4:1:1, 12bpp, (1 Cr & Cb sample per 4x1 Y samples)
Definition: pixfmt.h:73
int64_t black_start
pts start time of the first black picture
avfilter_execute_func * execute
Definition: internal.h:136
#define av_ts2str(ts)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: timestamp.h:54
A list of supported formats for one end of a filter link.
Definition: formats.h:65
An instance of a filter.
Definition: avfilter.h:341
int height
Definition: frame.h:372
#define av_freep(p)
planar YUV 4:4:0 (1 Cr & Cb sample per 1x2 Y samples)
Definition: pixfmt.h:99
static const AVOption blackdetect_options[]
internal API functions
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
int depth
Number of bits in the component.
Definition: pixdesc.h:58
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
static int filter_frame(AVFilterLink *inlink, AVFrame *picref)
#define AV_PIX_FMT_YUV422P16
Definition: pixfmt.h:411
int i
Definition: input.c:407
unsigned int * counter
#define AV_PIX_FMT_YUVA422P12
Definition: pixfmt.h:439