FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
af_pan.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2002 Anders Johansson <ajh@atri.curtin.edu.au>
3  * Copyright (c) 2011 Clément Bœsch <u pkh me>
4  * Copyright (c) 2011 Nicolas George <nicolas.george@normalesup.org>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * Audio panning filter (channels mixing)
26  * Original code written by Anders Johansson for MPlayer,
27  * reimplemented for FFmpeg.
28  */
29 
30 #include <stdio.h>
31 #include "libavutil/avstring.h"
33 #include "libavutil/opt.h"
35 #include "audio.h"
36 #include "avfilter.h"
37 #include "formats.h"
38 #include "internal.h"
39 
40 #define MAX_CHANNELS 64
41 
42 typedef struct PanContext {
43  const AVClass *class;
44  char *args;
47  int64_t need_renorm;
50 
52  /* channel mapping specific */
54  struct SwrContext *swr;
55 } PanContext;
56 
57 static void skip_spaces(char **arg)
58 {
59  int len = 0;
60 
61  sscanf(*arg, " %n", &len);
62  *arg += len;
63 }
64 
65 static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
66 {
67  char buf[8];
68  int len, i, channel_id = 0;
69  int64_t layout, layout0;
70 
71  skip_spaces(arg);
72  /* try to parse a channel name, e.g. "FL" */
73  if (sscanf(*arg, "%7[A-Z]%n", buf, &len)) {
74  layout0 = layout = av_get_channel_layout(buf);
75  /* channel_id <- first set bit in layout */
76  for (i = 32; i > 0; i >>= 1) {
77  if (layout >= (int64_t)1 << i) {
78  channel_id += i;
79  layout >>= i;
80  }
81  }
82  /* reject layouts that are not a single channel */
83  if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
84  return AVERROR(EINVAL);
85  *rchannel = channel_id;
86  *rnamed = 1;
87  *arg += len;
88  return 0;
89  }
90  /* try to parse a channel number, e.g. "c2" */
91  if (sscanf(*arg, "c%d%n", &channel_id, &len) &&
92  channel_id >= 0 && channel_id < MAX_CHANNELS) {
93  *rchannel = channel_id;
94  *rnamed = 0;
95  *arg += len;
96  return 0;
97  }
98  return AVERROR(EINVAL);
99 }
100 
102 {
103  PanContext *const pan = ctx->priv;
104  char *arg, *arg0, *tokenizer, *args = av_strdup(pan->args);
105  int out_ch_id, in_ch_id, len, named, ret, sign = 1;
106  int nb_in_channels[2] = { 0, 0 }; // number of unnamed and named input channels
107  double gain;
108 
109  if (!pan->args) {
110  av_log(ctx, AV_LOG_ERROR,
111  "pan filter needs a channel layout and a set "
112  "of channel definitions as parameter\n");
113  return AVERROR(EINVAL);
114  }
115  if (!args)
116  return AVERROR(ENOMEM);
117  arg = av_strtok(args, "|", &tokenizer);
118  if (!arg) {
119  av_log(ctx, AV_LOG_ERROR, "Channel layout not specified\n");
120  ret = AVERROR(EINVAL);
121  goto fail;
122  }
124  &pan->nb_output_channels, arg, ctx);
125  if (ret < 0)
126  goto fail;
127 
128  /* parse channel specifications */
129  while ((arg = arg0 = av_strtok(NULL, "|", &tokenizer))) {
130  /* channel name */
131  if (parse_channel_name(&arg, &out_ch_id, &named)) {
132  av_log(ctx, AV_LOG_ERROR,
133  "Expected out channel name, got \"%.8s\"\n", arg);
134  ret = AVERROR(EINVAL);
135  goto fail;
136  }
137  if (named) {
138  if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
139  av_log(ctx, AV_LOG_ERROR,
140  "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
141  ret = AVERROR(EINVAL);
142  goto fail;
143  }
144  /* get the channel number in the output channel layout:
145  * out_channel_layout & ((1 << out_ch_id) - 1) are all the
146  * channels that come before out_ch_id,
147  * so their count is the index of out_ch_id */
148  out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
149  }
150  if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
151  av_log(ctx, AV_LOG_ERROR,
152  "Invalid out channel name \"%.8s\"\n", arg0);
153  ret = AVERROR(EINVAL);
154  goto fail;
155  }
156  skip_spaces(&arg);
157  if (*arg == '=') {
158  arg++;
159  } else if (*arg == '<') {
160  pan->need_renorm |= (int64_t)1 << out_ch_id;
161  arg++;
162  } else {
163  av_log(ctx, AV_LOG_ERROR,
164  "Syntax error after channel name in \"%.8s\"\n", arg0);
165  ret = AVERROR(EINVAL);
166  goto fail;
167  }
168  /* gains */
169  while (1) {
170  gain = 1;
171  if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
172  arg += len;
173  if (parse_channel_name(&arg, &in_ch_id, &named)){
174  av_log(ctx, AV_LOG_ERROR,
175  "Expected in channel name, got \"%.8s\"\n", arg);
176  ret = AVERROR(EINVAL);
177  goto fail;
178  }
179  nb_in_channels[named]++;
180  if (nb_in_channels[!named]) {
181  av_log(ctx, AV_LOG_ERROR,
182  "Can not mix named and numbered channels\n");
183  ret = AVERROR(EINVAL);
184  goto fail;
185  }
186  pan->gain[out_ch_id][in_ch_id] = sign * gain;
187  skip_spaces(&arg);
188  if (!*arg)
189  break;
190  if (*arg == '-') {
191  sign = -1;
192  } else if (*arg != '+') {
193  av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
194  ret = AVERROR(EINVAL);
195  goto fail;
196  } else {
197  sign = 1;
198  }
199  arg++;
200  }
201  }
202  pan->need_renumber = !!nb_in_channels[1];
203 
204  ret = 0;
205 fail:
206  av_free(args);
207  return ret;
208 }
209 
210 static int are_gains_pure(const PanContext *pan)
211 {
212  int i, j;
213 
214  for (i = 0; i < MAX_CHANNELS; i++) {
215  int nb_gain = 0;
216 
217  for (j = 0; j < MAX_CHANNELS; j++) {
218  double gain = pan->gain[i][j];
219 
220  /* channel mapping is effective only if 0% or 100% of a channel is
221  * selected... */
222  if (gain != 0. && gain != 1.)
223  return 0;
224  /* ...and if the output channel is only composed of one input */
225  if (gain && nb_gain++)
226  return 0;
227  }
228  }
229  return 1;
230 }
231 
233 {
234  PanContext *pan = ctx->priv;
235  AVFilterLink *inlink = ctx->inputs[0];
236  AVFilterLink *outlink = ctx->outputs[0];
239  int ret;
240 
241  pan->pure_gains = are_gains_pure(pan);
242  /* libswr supports any sample and packing formats */
244  return ret;
245 
246  formats = ff_all_samplerates();
247  if ((ret = ff_set_common_samplerates(ctx, formats)) < 0)
248  return ret;
249 
250  // inlink supports any channel layout
251  layouts = ff_all_channel_counts();
252  if ((ret = ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts)) < 0)
253  return ret;
254 
255  // outlink supports only requested output channel layout
256  layouts = NULL;
257  if ((ret = ff_add_channel_layout(&layouts,
260  return ret;
261  return ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
262 }
263 
264 static int config_props(AVFilterLink *link)
265 {
266  AVFilterContext *ctx = link->dst;
267  PanContext *pan = ctx->priv;
268  char buf[1024], *cur;
269  int i, j, k, r;
270  double t;
271 
272  if (pan->need_renumber) {
273  // input channels were given by their name: renumber them
274  for (i = j = 0; i < MAX_CHANNELS; i++) {
275  if ((link->channel_layout >> i) & 1) {
276  for (k = 0; k < pan->nb_output_channels; k++)
277  pan->gain[k][j] = pan->gain[k][i];
278  j++;
279  }
280  }
281  }
282 
283  // sanity check; can't be done in query_formats since the inlink
284  // channel layout is unknown at that time
285  if (link->channels > MAX_CHANNELS ||
287  av_log(ctx, AV_LOG_ERROR,
288  "af_pan supports a maximum of %d channels. "
289  "Feel free to ask for a higher limit.\n", MAX_CHANNELS);
290  return AVERROR_PATCHWELCOME;
291  }
292 
293  // init libswresample context
294  pan->swr = swr_alloc_set_opts(pan->swr,
295  pan->out_channel_layout, link->format, link->sample_rate,
296  link->channel_layout, link->format, link->sample_rate,
297  0, ctx);
298  if (!pan->swr)
299  return AVERROR(ENOMEM);
300  if (!link->channel_layout) {
301  if (av_opt_set_int(pan->swr, "ich", link->channels, 0) < 0)
302  return AVERROR(EINVAL);
303  }
304  if (!pan->out_channel_layout) {
305  if (av_opt_set_int(pan->swr, "och", pan->nb_output_channels, 0) < 0)
306  return AVERROR(EINVAL);
307  }
308 
309  // gains are pure, init the channel mapping
310  if (pan->pure_gains) {
311 
312  // get channel map from the pure gains
313  for (i = 0; i < pan->nb_output_channels; i++) {
314  int ch_id = -1;
315  for (j = 0; j < link->channels; j++) {
316  if (pan->gain[i][j]) {
317  ch_id = j;
318  break;
319  }
320  }
321  pan->channel_map[i] = ch_id;
322  }
323 
324  av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
325  av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
327  } else {
328  // renormalize
329  for (i = 0; i < pan->nb_output_channels; i++) {
330  if (!((pan->need_renorm >> i) & 1))
331  continue;
332  t = 0;
333  for (j = 0; j < link->channels; j++)
334  t += fabs(pan->gain[i][j]);
335  if (t > -1E-5 && t < 1E-5) {
336  // t is almost 0 but not exactly, this is probably a mistake
337  if (t)
338  av_log(ctx, AV_LOG_WARNING,
339  "Degenerate coefficients while renormalizing\n");
340  continue;
341  }
342  for (j = 0; j < link->channels; j++)
343  pan->gain[i][j] /= t;
344  }
345  av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
346  av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
347  swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
348  }
349 
350  r = swr_init(pan->swr);
351  if (r < 0)
352  return r;
353 
354  // summary
355  for (i = 0; i < pan->nb_output_channels; i++) {
356  cur = buf;
357  for (j = 0; j < link->channels; j++) {
358  r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
359  j ? " + " : "", pan->gain[i][j], j);
360  cur += FFMIN(buf + sizeof(buf) - cur, r);
361  }
362  av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
363  }
364  // add channel mapping summary if possible
365  if (pan->pure_gains) {
366  av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
367  for (i = 0; i < pan->nb_output_channels; i++)
368  if (pan->channel_map[i] < 0)
369  av_log(ctx, AV_LOG_INFO, " M");
370  else
371  av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
372  av_log(ctx, AV_LOG_INFO, "\n");
373  return 0;
374  }
375  return 0;
376 }
377 
378 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
379 {
380  int ret;
381  int n = insamples->nb_samples;
382  AVFilterLink *const outlink = inlink->dst->outputs[0];
383  AVFrame *outsamples = ff_get_audio_buffer(outlink, n);
384  PanContext *pan = inlink->dst->priv;
385 
386  if (!outsamples) {
387  av_frame_free(&insamples);
388  return AVERROR(ENOMEM);
389  }
390  swr_convert(pan->swr, outsamples->extended_data, n,
391  (void *)insamples->extended_data, n);
392  av_frame_copy_props(outsamples, insamples);
393  outsamples->channel_layout = outlink->channel_layout;
394  outsamples->channels = outlink->channels;
395 
396  ret = ff_filter_frame(outlink, outsamples);
397  av_frame_free(&insamples);
398  return ret;
399 }
400 
402 {
403  PanContext *pan = ctx->priv;
404  swr_free(&pan->swr);
405 }
406 
407 #define OFFSET(x) offsetof(PanContext, x)
408 
409 static const AVOption pan_options[] = {
410  { "args", NULL, OFFSET(args), AV_OPT_TYPE_STRING, { .str = NULL }, CHAR_MIN, CHAR_MAX, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
411  { NULL }
412 };
413 
415 
416 static const AVFilterPad pan_inputs[] = {
417  {
418  .name = "default",
419  .type = AVMEDIA_TYPE_AUDIO,
420  .config_props = config_props,
421  .filter_frame = filter_frame,
422  },
423  { NULL }
424 };
425 
426 static const AVFilterPad pan_outputs[] = {
427  {
428  .name = "default",
429  .type = AVMEDIA_TYPE_AUDIO,
430  },
431  { NULL }
432 };
433 
435  .name = "pan",
436  .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
437  .priv_size = sizeof(PanContext),
438  .priv_class = &pan_class,
439  .init = init,
440  .uninit = uninit,
442  .inputs = pan_inputs,
443  .outputs = pan_outputs,
444 };
#define NULL
Definition: coverity.c:32
char * args
Definition: af_pan.c:44
#define MAX_CHANNELS
Definition: af_pan.c:40
double gain[MAX_CHANNELS][MAX_CHANNELS]
Definition: af_pan.c:46
This structure describes decoded (raw) audio or video data.
Definition: frame.h:201
AVOption.
Definition: opt.h:246
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
Main libavfilter public API header.
#define AV_OPT_FLAG_AUDIO_PARAM
Definition: opt.h:281
static int config_props(AVFilterLink *link)
Definition: af_pan.c:264
int av_get_channel_layout_nb_channels(uint64_t channel_layout)
Return the number of channels in the channel layout.
static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
Definition: af_pan.c:378
const char * name
Pad name.
Definition: internal.h:60
uint64_t av_get_channel_layout(const char *name)
Return a channel layout id that matches name, or 0 if no match is found.
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:346
int ff_channel_layouts_ref(AVFilterChannelLayouts *f, AVFilterChannelLayouts **ref)
Add *ref as a new reference to f.
Definition: formats.c:435
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1151
#define av_cold
Definition: attributes.h:82
AVOptions.
int need_renumber
Definition: af_pan.c:48
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:192
#define av_log(a,...)
AVFilterFormats * ff_all_formats(enum AVMediaType type)
Return a list of all formats supported by FFmpeg for the given media type.
Definition: formats.c:350
static const AVFilterPad pan_inputs[]
Definition: af_pan.c:416
static const AVOption pan_options[]
Definition: af_pan.c:409
A filter pad used for either input or output.
Definition: internal.h:54
libswresample public header
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
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:568
int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout)
Definition: formats.c:343
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:86
#define AV_OPT_FLAG_FILTERING_PARAM
a generic parameter which can be set by the user for filtering
Definition: opt.h:293
#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
The libswresample context.
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:179
const char * r
Definition: vf_curves.c:111
void * priv
private data for use by the filter
Definition: avfilter.h:353
int ff_parse_channel_layout(int64_t *ret, int *nret, const char *arg, void *log_ctx)
Parse a channel layout or a corresponding integer representation.
Definition: formats.c:662
static int query_formats(AVFilterContext *ctx)
Definition: af_pan.c:232
const char * arg
Definition: jacosubdec.c:66
int av_opt_set_int(void *obj, const char *name, int64_t val, int search_flags)
Definition: opt.c:558
struct SwrContext * swr
Definition: af_pan.c:54
#define fail()
Definition: checkasm.h:109
static int are_gains_pure(const PanContext *pan)
Definition: af_pan.c:210
uint64_t channel_layout
Channel layout of the audio data.
Definition: frame.h:379
int channels
number of audio channels, only used for audio.
Definition: frame.h:506
audio channel layout utility functions
#define E
Definition: avdct.c:32
#define FFMIN(a, b)
Definition: common.h:96
int swr_set_matrix(struct SwrContext *s, const double *matrix, int stride)
Set a customized remix matrix.
Definition: rematrix.c:64
int pure_gains
Definition: af_pan.c:51
static void skip_spaces(char **arg)
Definition: af_pan.c:57
AVFormatContext * ctx
Definition: movenc.c:48
struct SwrContext * swr_alloc_set_opts(struct SwrContext *s, int64_t out_ch_layout, enum AVSampleFormat out_sample_fmt, int out_sample_rate, int64_t in_ch_layout, enum AVSampleFormat in_sample_fmt, int in_sample_rate, int log_offset, void *log_ctx)
Allocate SwrContext if needed and set/reset common parameters.
Definition: swresample.c:59
AVFilter ff_af_pan
Definition: af_pan.c:434
int n
Definition: avisynth_c.h:684
static const AVFilterPad outputs[]
Definition: af_afftfilt.c:389
A list of supported channel layouts.
Definition: formats.h:85
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
int64_t out_channel_layout
Definition: af_pan.c:45
#define AV_LOG_INFO
Standard information.
Definition: log.h:187
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:379
char * av_strdup(const char *s)
Duplicate a string.
Definition: mem.c:237
av_cold void swr_free(SwrContext **ss)
Free the given SwrContext and set the pointer to NULL.
Definition: swresample.c:137
void * buf
Definition: avisynth_c.h:690
int swr_set_channel_mapping(struct SwrContext *s, const int *channel_map)
Set a customized input channel mapping.
Definition: swresample.c:52
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:144
#define OFFSET(x)
Definition: af_pan.c:407
int64_t need_renorm
Definition: af_pan.c:47
int channel_map[MAX_CHANNELS]
Definition: af_pan.c:53
const char * name
Filter name.
Definition: avfilter.h:148
#define snprintf
Definition: snprintf.h:34
int attribute_align_arg swr_convert(struct SwrContext *s, uint8_t *out_arg[SWR_CH_MAX], int out_count, const uint8_t *in_arg[SWR_CH_MAX], int in_count)
Definition: swresample.c:706
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:350
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
AVFilterFormats * ff_all_samplerates(void)
Definition: formats.c:395
AVFILTER_DEFINE_CLASS(pan)
char * av_strtok(char *s, const char *delim, char **saveptr)
Split the string into several tokens which can be accessed by successive calls to av_strtok()...
Definition: avstring.c:184
static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
Definition: af_pan.c:65
#define av_free(p)
int len
static av_cold int init(AVFilterContext *ctx)
Definition: af_pan.c:101
A list of supported formats for one end of a filter link.
Definition: formats.h:64
uint64_t layout
An instance of a filter.
Definition: avfilter.h:338
#define FF_COUNT2LAYOUT(c)
Encode a channel count as a channel layout.
Definition: formats.h:102
formats
Definition: signature.h:48
internal API functions
AVFilterChannelLayouts * ff_all_channel_counts(void)
Construct an AVFilterChannelLayouts coding for any channel layout, with known or unknown disposition...
Definition: formats.c:410
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:248
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:267
static av_cold void uninit(AVFilterContext *ctx)
Definition: af_pan.c:401
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:556
int av_frame_copy_props(AVFrame *dst, const AVFrame *src)
Copy only "metadata" fields from src to dst.
Definition: frame.c:603
av_cold int swr_init(struct SwrContext *s)
Initialize context after user parameters have been set.
Definition: swresample.c:152
static const AVFilterPad pan_outputs[]
Definition: af_pan.c:426
int nb_output_channels
Definition: af_pan.c:49