FFmpeg
avf_ahistogram.c
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1 /*
2  * Copyright (c) 2015 Paul B Mahol
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 #include "libavutil/avassert.h"
22 #include "libavutil/opt.h"
23 #include "libavutil/parseutils.h"
24 #include "avfilter.h"
25 #include "filters.h"
26 #include "formats.h"
27 #include "audio.h"
28 #include "video.h"
29 #include "internal.h"
30 
36 
37 typedef struct AudioHistogramContext {
38  const AVClass *class;
40  int w, h;
42  uint64_t *achistogram;
43  uint64_t *shistogram;
44  int ascale;
45  int scale;
46  float phisto;
48  int apos;
49  int ypos;
50  int slide;
51  int dmode;
52  int dchannels;
53  int count;
56  AVFrame *in[101];
57  int first;
60 
61 #define OFFSET(x) offsetof(AudioHistogramContext, x)
62 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
63 
64 static const AVOption ahistogram_options[] = {
65  { "dmode", "set method to display channels", OFFSET(dmode), AV_OPT_TYPE_INT, {.i64=SINGLE}, 0, NB_DMODES-1, FLAGS, "dmode" },
66  { "single", "all channels use single histogram", 0, AV_OPT_TYPE_CONST, {.i64=SINGLE}, 0, 0, FLAGS, "dmode" },
67  { "separate", "each channel have own histogram", 0, AV_OPT_TYPE_CONST, {.i64=SEPARATE}, 0, 0, FLAGS, "dmode" },
68  { "rate", "set video rate", OFFSET(frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str="25"}, 0, INT_MAX, FLAGS },
69  { "r", "set video rate", OFFSET(frame_rate), AV_OPT_TYPE_VIDEO_RATE, {.str="25"}, 0, INT_MAX, FLAGS },
70  { "size", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str="hd720"}, 0, 0, FLAGS },
71  { "s", "set video size", OFFSET(w), AV_OPT_TYPE_IMAGE_SIZE, {.str="hd720"}, 0, 0, FLAGS },
72  { "scale", "set display scale", OFFSET(scale), AV_OPT_TYPE_INT, {.i64=LOG}, LINEAR, NB_SCALES-1, FLAGS, "scale" },
73  { "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=LOG}, 0, 0, FLAGS, "scale" },
74  { "sqrt", "square root", 0, AV_OPT_TYPE_CONST, {.i64=SQRT}, 0, 0, FLAGS, "scale" },
75  { "cbrt", "cubic root", 0, AV_OPT_TYPE_CONST, {.i64=CBRT}, 0, 0, FLAGS, "scale" },
76  { "lin", "linear", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "scale" },
77  { "rlog", "reverse logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=RLOG}, 0, 0, FLAGS, "scale" },
78  { "ascale", "set amplitude scale", OFFSET(ascale), AV_OPT_TYPE_INT, {.i64=ALOG}, LINEAR, NB_ASCALES-1, FLAGS, "ascale" },
79  { "log", "logarithmic", 0, AV_OPT_TYPE_CONST, {.i64=ALOG}, 0, 0, FLAGS, "ascale" },
80  { "lin", "linear", 0, AV_OPT_TYPE_CONST, {.i64=ALINEAR}, 0, 0, FLAGS, "ascale" },
81  { "acount", "how much frames to accumulate", OFFSET(count), AV_OPT_TYPE_INT, {.i64=1}, -1, 100, FLAGS },
82  { "rheight", "set histogram ratio of window height", OFFSET(phisto), AV_OPT_TYPE_FLOAT, {.dbl=0.10}, 0, 1, FLAGS },
83  { "slide", "set sonogram sliding", OFFSET(slide), AV_OPT_TYPE_INT, {.i64=REPLACE}, 0, NB_SLIDES-1, FLAGS, "slide" },
84  { "replace", "replace old rows with new", 0, AV_OPT_TYPE_CONST, {.i64=REPLACE}, 0, 0, FLAGS, "slide" },
85  { "scroll", "scroll from top to bottom", 0, AV_OPT_TYPE_CONST, {.i64=SCROLL}, 0, 0, FLAGS, "slide" },
86  { NULL }
87 };
88 
89 AVFILTER_DEFINE_CLASS(ahistogram);
90 
92 {
95  AVFilterLink *inlink = ctx->inputs[0];
96  AVFilterLink *outlink = ctx->outputs[0];
98  static const enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUVA444P, AV_PIX_FMT_NONE };
99  int ret = AVERROR(EINVAL);
100 
101  formats = ff_make_format_list(sample_fmts);
102  if ((ret = ff_formats_ref (formats, &inlink->out_formats )) < 0 ||
103  (layouts = ff_all_channel_counts()) == NULL ||
104  (ret = ff_channel_layouts_ref (layouts, &inlink->out_channel_layouts)) < 0)
105  return ret;
106 
107  formats = ff_all_samplerates();
108  if ((ret = ff_formats_ref(formats, &inlink->out_samplerates)) < 0)
109  return ret;
110 
111  formats = ff_make_format_list(pix_fmts);
112  if ((ret = ff_formats_ref(formats, &outlink->in_formats)) < 0)
113  return ret;
114 
115  return 0;
116 }
117 
119 {
120  AVFilterContext *ctx = inlink->dst;
121  AudioHistogramContext *s = ctx->priv;
122 
124  s->dchannels = s->dmode == SINGLE ? 1 : inlink->channels;
125  s->shistogram = av_calloc(s->w, s->dchannels * sizeof(*s->shistogram));
126  if (!s->shistogram)
127  return AVERROR(ENOMEM);
128 
129  s->achistogram = av_calloc(s->w, s->dchannels * sizeof(*s->achistogram));
130  if (!s->achistogram)
131  return AVERROR(ENOMEM);
132 
133  return 0;
134 }
135 
136 static int config_output(AVFilterLink *outlink)
137 {
138  AudioHistogramContext *s = outlink->src->priv;
139 
140  outlink->w = s->w;
141  outlink->h = s->h;
142  outlink->sample_aspect_ratio = (AVRational){1,1};
143  outlink->frame_rate = s->frame_rate;
144 
145  s->histogram_h = s->h * s->phisto;
146  s->ypos = s->h * s->phisto;
147 
148  if (s->dmode == SEPARATE) {
149  s->combine_buffer = av_malloc_array(outlink->w * 3, sizeof(*s->combine_buffer));
150  if (!s->combine_buffer)
151  return AVERROR(ENOMEM);
152  }
153 
154  return 0;
155 }
156 
158 {
159  AVFilterContext *ctx = inlink->dst;
160  AVFilterLink *outlink = ctx->outputs[0];
161  AudioHistogramContext *s = ctx->priv;
162  const int H = s->histogram_h;
163  const int w = s->w;
164  int c, y, n, p, bin;
165  uint64_t acmax = 1;
166  AVFrame *clone;
167 
168  if (!s->out || s->out->width != outlink->w ||
169  s->out->height != outlink->h) {
170  av_frame_free(&s->out);
171  s->out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
172  if (!s->out) {
173  av_frame_free(&in);
174  return AVERROR(ENOMEM);
175  }
176  for (n = H; n < s->h; n++) {
177  memset(s->out->data[0] + n * s->out->linesize[0], 0, w);
178  memset(s->out->data[1] + n * s->out->linesize[0], 127, w);
179  memset(s->out->data[2] + n * s->out->linesize[0], 127, w);
180  memset(s->out->data[3] + n * s->out->linesize[0], 0, w);
181  }
182  }
183 
184  if (s->dmode == SEPARATE) {
185  for (y = 0; y < w; y++) {
186  s->combine_buffer[3 * y ] = 0;
187  s->combine_buffer[3 * y + 1] = 127.5;
188  s->combine_buffer[3 * y + 2] = 127.5;
189  }
190  }
191 
192  for (n = 0; n < H; n++) {
193  memset(s->out->data[0] + n * s->out->linesize[0], 0, w);
194  memset(s->out->data[1] + n * s->out->linesize[0], 127, w);
195  memset(s->out->data[2] + n * s->out->linesize[0], 127, w);
196  memset(s->out->data[3] + n * s->out->linesize[0], 0, w);
197  }
198  s->out->pts = in->pts;
199 
200  s->first = s->frame_count;
201 
202  switch (s->ascale) {
203  case ALINEAR:
204  for (c = 0; c < inlink->channels; c++) {
205  const float *src = (const float *)in->extended_data[c];
206  uint64_t *achistogram = &s->achistogram[(s->dmode == SINGLE ? 0: c) * w];
207 
208  for (n = 0; n < in->nb_samples; n++) {
209  bin = lrint(av_clipf(fabsf(src[n]), 0, 1) * (w - 1));
210 
211  achistogram[bin]++;
212  }
213 
214  if (s->in[s->first] && s->count >= 0) {
215  uint64_t *shistogram = &s->shistogram[(s->dmode == SINGLE ? 0: c) * w];
216  const float *src2 = (const float *)s->in[s->first]->extended_data[c];
217 
218  for (n = 0; n < in->nb_samples; n++) {
219  bin = lrint(av_clipf(fabsf(src2[n]), 0, 1) * (w - 1));
220 
221  shistogram[bin]++;
222  }
223  }
224  }
225  break;
226  case ALOG:
227  for (c = 0; c < inlink->channels; c++) {
228  const float *src = (const float *)in->extended_data[c];
229  uint64_t *achistogram = &s->achistogram[(s->dmode == SINGLE ? 0: c) * w];
230 
231  for (n = 0; n < in->nb_samples; n++) {
232  bin = lrint(av_clipf(1 + log10(fabsf(src[n])) / 6, 0, 1) * (w - 1));
233 
234  achistogram[bin]++;
235  }
236 
237  if (s->in[s->first] && s->count >= 0) {
238  uint64_t *shistogram = &s->shistogram[(s->dmode == SINGLE ? 0: c) * w];
239  const float *src2 = (const float *)s->in[s->first]->extended_data[c];
240 
241  for (n = 0; n < in->nb_samples; n++) {
242  bin = lrint(av_clipf(1 + log10(fabsf(src2[n])) / 6, 0, 1) * (w - 1));
243 
244  shistogram[bin]++;
245  }
246  }
247  }
248  break;
249  }
250 
251  av_frame_free(&s->in[s->frame_count]);
252  s->in[s->frame_count] = in;
253  s->frame_count++;
254  if (s->frame_count > s->count)
255  s->frame_count = 0;
256 
257  for (n = 0; n < w * s->dchannels; n++) {
258  acmax = FFMAX(s->achistogram[n] - s->shistogram[n], acmax);
259  }
260 
261  for (c = 0; c < s->dchannels; c++) {
262  uint64_t *shistogram = &s->shistogram[c * w];
263  uint64_t *achistogram = &s->achistogram[c * w];
264  float yf, uf, vf;
265 
266  if (s->dmode == SEPARATE) {
267  yf = 256.0f / s->dchannels;
268  uf = yf * M_PI;
269  vf = yf * M_PI;
270  uf *= 0.5 * sin((2 * M_PI * c) / s->dchannels);
271  vf *= 0.5 * cos((2 * M_PI * c) / s->dchannels);
272  }
273 
274  for (n = 0; n < w; n++) {
275  double a, aa;
276  int h;
277 
278  a = achistogram[n] - shistogram[n];
279 
280  switch (s->scale) {
281  case LINEAR:
282  aa = a / (double)acmax;
283  break;
284  case SQRT:
285  aa = sqrt(a) / sqrt(acmax);
286  break;
287  case CBRT:
288  aa = cbrt(a) / cbrt(acmax);
289  break;
290  case LOG:
291  aa = log2(a + 1) / log2(acmax + 1);
292  break;
293  case RLOG:
294  aa = 1. - log2(a + 1) / log2(acmax + 1);
295  if (aa == 1.)
296  aa = 0;
297  break;
298  default:
299  av_assert0(0);
300  }
301 
302  h = aa * (H - 1);
303 
304  if (s->dmode == SINGLE) {
305 
306  for (y = H - h; y < H; y++) {
307  s->out->data[0][y * s->out->linesize[0] + n] = 255;
308  s->out->data[3][y * s->out->linesize[0] + n] = 255;
309  }
310 
311  if (s->h - H > 0) {
312  h = aa * 255;
313 
314  s->out->data[0][s->ypos * s->out->linesize[0] + n] = h;
315  s->out->data[1][s->ypos * s->out->linesize[1] + n] = 127;
316  s->out->data[2][s->ypos * s->out->linesize[2] + n] = 127;
317  s->out->data[3][s->ypos * s->out->linesize[3] + n] = 255;
318  }
319  } else if (s->dmode == SEPARATE) {
320  float *out = &s->combine_buffer[3 * n];
321  int old;
322 
323  old = s->out->data[0][(H - h) * s->out->linesize[0] + n];
324  for (y = H - h; y < H; y++) {
325  if (s->out->data[0][y * s->out->linesize[0] + n] != old)
326  break;
327  old = s->out->data[0][y * s->out->linesize[0] + n];
328  s->out->data[0][y * s->out->linesize[0] + n] = yf;
329  s->out->data[1][y * s->out->linesize[1] + n] = 128+uf;
330  s->out->data[2][y * s->out->linesize[2] + n] = 128+vf;
331  s->out->data[3][y * s->out->linesize[3] + n] = 255;
332  }
333 
334  out[0] += aa * yf;
335  out[1] += aa * uf;
336  out[2] += aa * vf;
337  }
338  }
339  }
340 
341  if (s->h - H > 0) {
342  if (s->dmode == SEPARATE) {
343  for (n = 0; n < w; n++) {
344  float *cb = &s->combine_buffer[3 * n];
345 
346  s->out->data[0][s->ypos * s->out->linesize[0] + n] = cb[0];
347  s->out->data[1][s->ypos * s->out->linesize[1] + n] = cb[1];
348  s->out->data[2][s->ypos * s->out->linesize[2] + n] = cb[2];
349  s->out->data[3][s->ypos * s->out->linesize[3] + n] = 255;
350  }
351  }
352 
353  if (s->slide == SCROLL) {
354  for (p = 0; p < 4; p++) {
355  for (y = s->h; y >= H + 1; y--) {
356  memmove(s->out->data[p] + (y ) * s->out->linesize[p],
357  s->out->data[p] + (y-1) * s->out->linesize[p], w);
358  }
359  }
360  }
361 
362  s->ypos++;
363  if (s->slide == SCROLL || s->ypos >= s->h)
364  s->ypos = H;
365  }
366 
367  clone = av_frame_clone(s->out);
368  if (!clone)
369  return AVERROR(ENOMEM);
370 
371  return ff_filter_frame(outlink, clone);
372 }
373 
375 {
376  AVFilterLink *inlink = ctx->inputs[0];
377  AVFilterLink *outlink = ctx->outputs[0];
378  AudioHistogramContext *s = ctx->priv;
379  AVFrame *in;
380  int ret;
381 
382  FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
383 
384  ret = ff_inlink_consume_samples(inlink, s->nb_samples, s->nb_samples, &in);
385  if (ret < 0)
386  return ret;
387  if (ret > 0)
388  return filter_frame(inlink, in);
389 
390  FF_FILTER_FORWARD_STATUS(inlink, outlink);
391  FF_FILTER_FORWARD_WANTED(outlink, inlink);
392 
393  return FFERROR_NOT_READY;
394 }
395 
397 {
398  AudioHistogramContext *s = ctx->priv;
399  int i;
400 
401  av_frame_free(&s->out);
402  av_freep(&s->shistogram);
403  av_freep(&s->achistogram);
405  for (i = 0; i < 101; i++)
406  av_frame_free(&s->in[i]);
407 }
408 
409 static const AVFilterPad ahistogram_inputs[] = {
410  {
411  .name = "default",
412  .type = AVMEDIA_TYPE_AUDIO,
413  .config_props = config_input,
414  },
415  { NULL }
416 };
417 
418 static const AVFilterPad ahistogram_outputs[] = {
419  {
420  .name = "default",
421  .type = AVMEDIA_TYPE_VIDEO,
422  .config_props = config_output,
423  },
424  { NULL }
425 };
426 
428  .name = "ahistogram",
429  .description = NULL_IF_CONFIG_SMALL("Convert input audio to histogram video output."),
430  .uninit = uninit,
431  .query_formats = query_formats,
432  .priv_size = sizeof(AudioHistogramContext),
433  .activate = activate,
434  .inputs = ahistogram_inputs,
435  .outputs = ahistogram_outputs,
436  .priv_class = &ahistogram_class,
437 };
float, planar
Definition: samplefmt.h:69
#define NULL
Definition: coverity.c:32
static const AVFilterPad ahistogram_inputs[]
This structure describes decoded (raw) audio or video data.
Definition: frame.h:308
AVOption.
Definition: opt.h:248
Main libavfilter public API header.
FF_FILTER_FORWARD_STATUS(inlink, outlink)
int num
Numerator.
Definition: rational.h:59
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:36
return FFERROR_NOT_READY
AVFrame * ff_get_video_buffer(AVFilterLink *link, int w, int h)
Request a picture buffer with a specific set of permissions.
Definition: video.c:99
#define log2(x)
Definition: libm.h:404
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:283
DisplayScale
const char * name
Pad name.
Definition: internal.h:60
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:346
AmplitudeScale
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
int ff_channel_layouts_ref(AVFilterChannelLayouts *f, AVFilterChannelLayouts **ref)
Add *ref as a new reference to f.
Definition: formats.c:465
static double cb(void *priv, double x, double y)
Definition: vf_geq.c:215
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1091
#define av_cold
Definition: attributes.h:88
AVOptions.
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
static int query_formats(AVFilterContext *ctx)
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:401
#define OFFSET(x)
static const AVOption ahistogram_options[]
static int config_output(AVFilterLink *outlink)
SlideMode
#define FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink)
Forward the status on an output link to an input link.
Definition: filters.h:199
A filter pad used for either input or output.
Definition: internal.h:54
#define src
Definition: vp8dsp.c:254
int width
Definition: frame.h:366
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:203
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:153
void * priv
private data for use by the filter
Definition: avfilter.h:353
#define cbrt
Definition: tablegen.h:35
simple assert() macros that are a bit more flexible than ISO C assert().
static int config_input(AVFilterLink *inlink)
GLsizei count
Definition: opengl_enc.c:108
#define FFMAX(a, b)
Definition: common.h:94
#define FLAGS
AVFILTER_DEFINE_CLASS(ahistogram)
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
int ff_formats_ref(AVFilterFormats *f, AVFilterFormats **ref)
Add *ref as a new reference to formats.
Definition: formats.c:470
static int activate(AVFilterContext *ctx)
AVFormatContext * ctx
Definition: movenc.c:48
#define s(width, name)
Definition: cbs_vp9.c:257
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:553
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
A list of supported channel layouts.
Definition: formats.h:85
static const AVFilterPad ahistogram_outputs[]
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:339
planar YUV 4:4:4 32bpp, (1 Cr & Cb sample per 1x1 Y & A samples)
Definition: pixfmt.h:177
int ff_inlink_consume_samples(AVFilterLink *link, unsigned min, unsigned max, AVFrame **rframe)
Take samples from the link&#39;s FIFO and update the link&#39;s stats.
Definition: avfilter.c:1511
HistogramMode
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
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
Rational number (pair of numerator and denominator).
Definition: rational.h:58
offset must point to AVRational
Definition: opt.h:238
const char * name
Filter name.
Definition: avfilter.h:148
offset must point to two consecutive integers
Definition: opt.h:235
misc parsing utilities
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:270
AVFilterFormats * ff_all_samplerates(void)
Definition: formats.c:425
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:322
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
static av_cold void uninit(AVFilterContext *ctx)
int den
Denominator.
Definition: rational.h:60
FF_FILTER_FORWARD_WANTED(outlink, inlink)
#define H
Definition: pixlet.c:39
A list of supported formats for one end of a filter link.
Definition: formats.h:64
#define lrint
Definition: tablegen.h:53
AVFilter ff_avf_ahistogram
An instance of a filter.
Definition: avfilter.h:338
static enum AVSampleFormat sample_fmts[]
Definition: adpcmenc.c:836
int height
Definition: frame.h:366
#define av_freep(p)
#define M_PI
Definition: mathematics.h:52
#define av_malloc_array(a, b)
formats
Definition: signature.h:48
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
AVFilterChannelLayouts * ff_all_channel_counts(void)
Construct an AVFilterChannelLayouts coding for any channel layout, with known or unknown disposition...
Definition: formats.c:440
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:355
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:374
for(j=16;j >0;--j)
int i
Definition: input.c:407
DisplayMode