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path: root/libavfilter/af_pan.c (plain)
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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"
32#include "libavutil/channel_layout.h"
33#include "libavutil/opt.h"
34#include "libswresample/swresample.h"
35#include "audio.h"
36#include "avfilter.h"
37#include "formats.h"
38#include "internal.h"
39
40#define MAX_CHANNELS 64
41
42typedef struct PanContext {
43 const AVClass *class;
44 char *args;
45 int64_t out_channel_layout;
46 double gain[MAX_CHANNELS][MAX_CHANNELS];
47 int64_t need_renorm;
48 int need_renumber;
49 int nb_output_channels;
50
51 int pure_gains;
52 /* channel mapping specific */
53 int channel_map[MAX_CHANNELS];
54 struct SwrContext *swr;
55} PanContext;
56
57static void skip_spaces(char **arg)
58{
59 int len = 0;
60
61 sscanf(*arg, " %n", &len);
62 *arg += len;
63}
64
65static 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
101static av_cold int init(AVFilterContext *ctx)
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 }
123 ret = ff_parse_channel_layout(&pan->out_channel_layout,
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;
205fail:
206 av_free(args);
207 return ret;
208}
209
210static 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
232static int query_formats(AVFilterContext *ctx)
233{
234 PanContext *pan = ctx->priv;
235 AVFilterLink *inlink = ctx->inputs[0];
236 AVFilterLink *outlink = ctx->outputs[0];
237 AVFilterFormats *formats = NULL;
238 AVFilterChannelLayouts *layouts;
239 int ret;
240
241 pan->pure_gains = are_gains_pure(pan);
242 /* libswr supports any sample and packing formats */
243 if ((ret = ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO))) < 0)
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,
258 pan->out_channel_layout ? pan->out_channel_layout :
259 FF_COUNT2LAYOUT(pan->nb_output_channels))) < 0)
260 return ret;
261 return ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
262}
263
264static 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 ||
286 pan->nb_output_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);
326 swr_set_channel_mapping(pan->swr, pan->channel_map);
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
378static 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 return AVERROR(ENOMEM);
388 swr_convert(pan->swr, outsamples->extended_data, n,
389 (void *)insamples->extended_data, n);
390 av_frame_copy_props(outsamples, insamples);
391 outsamples->channel_layout = outlink->channel_layout;
392 av_frame_set_channels(outsamples, outlink->channels);
393
394 ret = ff_filter_frame(outlink, outsamples);
395 av_frame_free(&insamples);
396 return ret;
397}
398
399static av_cold void uninit(AVFilterContext *ctx)
400{
401 PanContext *pan = ctx->priv;
402 swr_free(&pan->swr);
403}
404
405#define OFFSET(x) offsetof(PanContext, x)
406
407static const AVOption pan_options[] = {
408 { "args", NULL, OFFSET(args), AV_OPT_TYPE_STRING, { .str = NULL }, CHAR_MIN, CHAR_MAX, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
409 { NULL }
410};
411
412AVFILTER_DEFINE_CLASS(pan);
413
414static const AVFilterPad pan_inputs[] = {
415 {
416 .name = "default",
417 .type = AVMEDIA_TYPE_AUDIO,
418 .config_props = config_props,
419 .filter_frame = filter_frame,
420 },
421 { NULL }
422};
423
424static const AVFilterPad pan_outputs[] = {
425 {
426 .name = "default",
427 .type = AVMEDIA_TYPE_AUDIO,
428 },
429 { NULL }
430};
431
432AVFilter ff_af_pan = {
433 .name = "pan",
434 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
435 .priv_size = sizeof(PanContext),
436 .priv_class = &pan_class,
437 .init = init,
438 .uninit = uninit,
439 .query_formats = query_formats,
440 .inputs = pan_inputs,
441 .outputs = pan_outputs,
442};
443
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