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>
6 * This file is part of FFmpeg.
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.
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.
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
25 * Audio panning filter (channels mixing)
26 * Original code written by Anders Johansson for MPlayer,
27 * reimplemented for FFmpeg.
31 #include "libavutil/avstring.h"
32 #include "libavutil/channel_layout.h"
33 #include "libavutil/opt.h"
34 #include "libswresample/swresample.h"
40 #define MAX_CHANNELS 64
42 typedef struct PanContext {
45 int64_t out_channel_layout;
46 double gain[MAX_CHANNELS][MAX_CHANNELS];
49 int nb_output_channels;
52 /* channel mapping specific */
53 int channel_map[MAX_CHANNELS];
54 struct SwrContext *swr;
57 static void skip_spaces(char **arg)
61 sscanf(*arg, " %n", &len);
65 static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
68 int len, i, channel_id = 0;
69 int64_t layout, layout0;
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) {
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;
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;
98 return AVERROR(EINVAL);
101 static av_cold int init(AVFilterContext *ctx)
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
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);
116 return AVERROR(ENOMEM);
117 arg = av_strtok(args, "|", &tokenizer);
119 av_log(ctx, AV_LOG_ERROR, "Channel layout not specified\n");
120 ret = AVERROR(EINVAL);
123 ret = ff_parse_channel_layout(&pan->out_channel_layout,
124 &pan->nb_output_channels, arg, ctx);
128 /* parse channel specifications */
129 while ((arg = arg0 = av_strtok(NULL, "|", &tokenizer))) {
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);
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);
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));
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);
159 } else if (*arg == '<') {
160 pan->need_renorm |= (int64_t)1 << out_ch_id;
163 av_log(ctx, AV_LOG_ERROR,
164 "Syntax error after channel name in \"%.8s\"\n", arg0);
165 ret = AVERROR(EINVAL);
172 if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
174 if (parse_channel_name(&arg, &in_ch_id, &named)){
175 av_log(ctx, AV_LOG_ERROR,
176 "Expected in channel name, got \"%.8s\"\n", arg);
177 ret = AVERROR(EINVAL);
180 nb_in_channels[named]++;
181 if (nb_in_channels[!named]) {
182 av_log(ctx, AV_LOG_ERROR,
183 "Can not mix named and numbered channels\n");
184 ret = AVERROR(EINVAL);
187 pan->gain[out_ch_id][in_ch_id] = sign * gain;
193 } else if (*arg != '+') {
194 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
195 ret = AVERROR(EINVAL);
203 pan->need_renumber = !!nb_in_channels[1];
211 static int are_gains_pure(const PanContext *pan)
215 for (i = 0; i < MAX_CHANNELS; i++) {
218 for (j = 0; j < MAX_CHANNELS; j++) {
219 double gain = pan->gain[i][j];
221 /* channel mapping is effective only if 0% or 100% of a channel is
223 if (gain != 0. && gain != 1.)
225 /* ...and if the output channel is only composed of one input */
226 if (gain && nb_gain++)
233 static int query_formats(AVFilterContext *ctx)
235 PanContext *pan = ctx->priv;
236 AVFilterLink *inlink = ctx->inputs[0];
237 AVFilterLink *outlink = ctx->outputs[0];
238 AVFilterFormats *formats = NULL;
239 AVFilterChannelLayouts *layouts;
242 pan->pure_gains = are_gains_pure(pan);
243 /* libswr supports any sample and packing formats */
244 if ((ret = ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO))) < 0)
247 formats = ff_all_samplerates();
248 if ((ret = ff_set_common_samplerates(ctx, formats)) < 0)
251 // inlink supports any channel layout
252 layouts = ff_all_channel_counts();
253 if ((ret = ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts)) < 0)
256 // outlink supports only requested output channel layout
258 if ((ret = ff_add_channel_layout(&layouts,
259 pan->out_channel_layout ? pan->out_channel_layout :
260 FF_COUNT2LAYOUT(pan->nb_output_channels))) < 0)
262 return ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
265 static int config_props(AVFilterLink *link)
267 AVFilterContext *ctx = link->dst;
268 PanContext *pan = ctx->priv;
269 char buf[1024], *cur;
273 if (pan->need_renumber) {
274 // input channels were given by their name: renumber them
275 for (i = j = 0; i < MAX_CHANNELS; i++) {
276 if ((link->channel_layout >> i) & 1) {
277 for (k = 0; k < pan->nb_output_channels; k++)
278 pan->gain[k][j] = pan->gain[k][i];
284 // sanity check; can't be done in query_formats since the inlink
285 // channel layout is unknown at that time
286 if (link->channels > MAX_CHANNELS ||
287 pan->nb_output_channels > MAX_CHANNELS) {
288 av_log(ctx, AV_LOG_ERROR,
289 "af_pan supports a maximum of %d channels. "
290 "Feel free to ask for a higher limit.\n", MAX_CHANNELS);
291 return AVERROR_PATCHWELCOME;
294 // init libswresample context
295 pan->swr = swr_alloc_set_opts(pan->swr,
296 pan->out_channel_layout, link->format, link->sample_rate,
297 link->channel_layout, link->format, link->sample_rate,
300 return AVERROR(ENOMEM);
301 if (!link->channel_layout) {
302 if (av_opt_set_int(pan->swr, "ich", link->channels, 0) < 0)
303 return AVERROR(EINVAL);
305 if (!pan->out_channel_layout) {
306 if (av_opt_set_int(pan->swr, "och", pan->nb_output_channels, 0) < 0)
307 return AVERROR(EINVAL);
310 // gains are pure, init the channel mapping
311 if (pan->pure_gains) {
313 // get channel map from the pure gains
314 for (i = 0; i < pan->nb_output_channels; i++) {
316 for (j = 0; j < link->channels; j++) {
317 if (pan->gain[i][j]) {
322 pan->channel_map[i] = ch_id;
325 av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
326 av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
327 swr_set_channel_mapping(pan->swr, pan->channel_map);
330 for (i = 0; i < pan->nb_output_channels; i++) {
331 if (!((pan->need_renorm >> i) & 1))
334 for (j = 0; j < link->channels; j++)
335 t += fabs(pan->gain[i][j]);
336 if (t > -1E-5 && t < 1E-5) {
337 // t is almost 0 but not exactly, this is probably a mistake
339 av_log(ctx, AV_LOG_WARNING,
340 "Degenerate coefficients while renormalizing\n");
343 for (j = 0; j < link->channels; j++)
344 pan->gain[i][j] /= t;
346 av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
347 av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
348 swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
351 r = swr_init(pan->swr);
356 for (i = 0; i < pan->nb_output_channels; i++) {
358 for (j = 0; j < link->channels; j++) {
359 r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
360 j ? " + " : "", pan->gain[i][j], j);
361 cur += FFMIN(buf + sizeof(buf) - cur, r);
363 av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
365 // add channel mapping summary if possible
366 if (pan->pure_gains) {
367 av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
368 for (i = 0; i < pan->nb_output_channels; i++)
369 if (pan->channel_map[i] < 0)
370 av_log(ctx, AV_LOG_INFO, " M");
372 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
373 av_log(ctx, AV_LOG_INFO, "\n");
379 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
382 int n = insamples->nb_samples;
383 AVFilterLink *const outlink = inlink->dst->outputs[0];
384 AVFrame *outsamples = ff_get_audio_buffer(outlink, n);
385 PanContext *pan = inlink->dst->priv;
388 av_frame_free(&insamples);
389 return AVERROR(ENOMEM);
391 swr_convert(pan->swr, outsamples->extended_data, n,
392 (void *)insamples->extended_data, n);
393 av_frame_copy_props(outsamples, insamples);
394 outsamples->channel_layout = outlink->channel_layout;
395 outsamples->channels = outlink->channels;
397 ret = ff_filter_frame(outlink, outsamples);
398 av_frame_free(&insamples);
402 static av_cold void uninit(AVFilterContext *ctx)
404 PanContext *pan = ctx->priv;
408 #define OFFSET(x) offsetof(PanContext, x)
410 static const AVOption pan_options[] = {
411 { "args", NULL, OFFSET(args), AV_OPT_TYPE_STRING, { .str = NULL }, CHAR_MIN, CHAR_MAX, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
415 AVFILTER_DEFINE_CLASS(pan);
417 static const AVFilterPad pan_inputs[] = {
420 .type = AVMEDIA_TYPE_AUDIO,
421 .config_props = config_props,
422 .filter_frame = filter_frame,
427 static const AVFilterPad pan_outputs[] = {
430 .type = AVMEDIA_TYPE_AUDIO,
435 AVFilter ff_af_pan = {
437 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
438 .priv_size = sizeof(PanContext),
439 .priv_class = &pan_class,
442 .query_formats = query_formats,
443 .inputs = pan_inputs,
444 .outputs = pan_outputs,