2 * Copyright (c) 2002 Anders Johansson <ajh@atri.curtin.edu.au>
3 * Copyright (c) 2011 Clément Bœsch <ubitux@gmail.com>
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 63
42 typedef struct PanContext {
45 int64_t out_channel_layout;
46 double gain[MAX_CHANNELS][MAX_CHANNELS];
49 int nb_input_channels;
50 int nb_output_channels;
53 /* channel mapping specific */
54 int channel_map[SWR_CH_MAX];
55 struct SwrContext *swr;
58 static void skip_spaces(char **arg)
62 sscanf(*arg, " %n", &len);
66 static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
69 int len, i, channel_id = 0;
70 int64_t layout, layout0;
73 /* try to parse a channel name, e.g. "FL" */
74 if (sscanf(*arg, "%7[A-Z]%n", buf, &len)) {
75 layout0 = layout = av_get_channel_layout(buf);
76 /* channel_id <- first set bit in layout */
77 for (i = 32; i > 0; i >>= 1) {
78 if (layout >= (int64_t)1 << i) {
83 /* reject layouts that are not a single channel */
84 if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
85 return AVERROR(EINVAL);
86 *rchannel = channel_id;
91 /* try to parse a channel number, e.g. "c2" */
92 if (sscanf(*arg, "c%d%n", &channel_id, &len) &&
93 channel_id >= 0 && channel_id < MAX_CHANNELS) {
94 *rchannel = channel_id;
99 return AVERROR(EINVAL);
102 static av_cold int init(AVFilterContext *ctx)
104 PanContext *const pan = ctx->priv;
105 char *arg, *arg0, *tokenizer, *args = av_strdup(pan->args);
106 int out_ch_id, in_ch_id, len, named, ret;
107 int nb_in_channels[2] = { 0, 0 }; // number of unnamed and named input channels
111 av_log(ctx, AV_LOG_ERROR,
112 "pan filter needs a channel layout and a set "
113 "of channels definitions as parameter\n");
114 return AVERROR(EINVAL);
117 return AVERROR(ENOMEM);
118 arg = av_strtok(args, "|", &tokenizer);
119 ret = ff_parse_channel_layout(&pan->out_channel_layout, arg, ctx);
122 pan->nb_output_channels = av_get_channel_layout_nb_channels(pan->out_channel_layout);
124 /* parse channel specifications */
125 while ((arg = arg0 = av_strtok(NULL, "|", &tokenizer))) {
127 if (parse_channel_name(&arg, &out_ch_id, &named)) {
128 av_log(ctx, AV_LOG_ERROR,
129 "Expected out channel name, got \"%.8s\"\n", arg);
130 ret = AVERROR(EINVAL);
134 if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
135 av_log(ctx, AV_LOG_ERROR,
136 "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
137 ret = AVERROR(EINVAL);
140 /* get the channel number in the output channel layout:
141 * out_channel_layout & ((1 << out_ch_id) - 1) are all the
142 * channels that come before out_ch_id,
143 * so their count is the index of out_ch_id */
144 out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
146 if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
147 av_log(ctx, AV_LOG_ERROR,
148 "Invalid out channel name \"%.8s\"\n", arg0);
149 ret = AVERROR(EINVAL);
155 } else if (*arg == '<') {
156 pan->need_renorm |= (int64_t)1 << out_ch_id;
159 av_log(ctx, AV_LOG_ERROR,
160 "Syntax error after channel name in \"%.8s\"\n", arg0);
161 ret = AVERROR(EINVAL);
167 if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
169 if (parse_channel_name(&arg, &in_ch_id, &named)){
170 av_log(ctx, AV_LOG_ERROR,
171 "Expected in channel name, got \"%.8s\"\n", arg);
172 ret = AVERROR(EINVAL);
175 nb_in_channels[named]++;
176 if (nb_in_channels[!named]) {
177 av_log(ctx, AV_LOG_ERROR,
178 "Can not mix named and numbered channels\n");
179 ret = AVERROR(EINVAL);
182 pan->gain[out_ch_id][in_ch_id] = gain;
187 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
188 ret = AVERROR(EINVAL);
194 pan->need_renumber = !!nb_in_channels[1];
202 static int are_gains_pure(const PanContext *pan)
206 for (i = 0; i < MAX_CHANNELS; i++) {
209 for (j = 0; j < MAX_CHANNELS; j++) {
210 double gain = pan->gain[i][j];
212 /* channel mapping is effective only if 0% or 100% of a channel is
214 if (gain != 0. && gain != 1.)
216 /* ...and if the output channel is only composed of one input */
217 if (gain && nb_gain++)
224 static int query_formats(AVFilterContext *ctx)
226 PanContext *pan = ctx->priv;
227 AVFilterLink *inlink = ctx->inputs[0];
228 AVFilterLink *outlink = ctx->outputs[0];
229 AVFilterFormats *formats = NULL;
230 AVFilterChannelLayouts *layouts;
232 pan->pure_gains = are_gains_pure(pan);
233 /* libswr supports any sample and packing formats */
234 ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
236 formats = ff_all_samplerates();
238 return AVERROR(ENOMEM);
239 ff_set_common_samplerates(ctx, formats);
241 // inlink supports any channel layout
242 layouts = ff_all_channel_layouts();
243 ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
245 // outlink supports only requested output channel layout
247 ff_add_channel_layout(&layouts, pan->out_channel_layout);
248 ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
252 static int config_props(AVFilterLink *link)
254 AVFilterContext *ctx = link->dst;
255 PanContext *pan = ctx->priv;
256 char buf[1024], *cur;
260 pan->nb_input_channels = av_get_channel_layout_nb_channels(link->channel_layout);
261 if (pan->need_renumber) {
262 // input channels were given by their name: renumber them
263 for (i = j = 0; i < MAX_CHANNELS; i++) {
264 if ((link->channel_layout >> i) & 1) {
265 for (k = 0; k < pan->nb_output_channels; k++)
266 pan->gain[k][j] = pan->gain[k][i];
272 // sanity check; can't be done in query_formats since the inlink
273 // channel layout is unknown at that time
274 if (pan->nb_input_channels > SWR_CH_MAX ||
275 pan->nb_output_channels > SWR_CH_MAX) {
276 av_log(ctx, AV_LOG_ERROR,
277 "libswresample support a maximum of %d channels. "
278 "Feel free to ask for a higher limit.\n", SWR_CH_MAX);
279 return AVERROR_PATCHWELCOME;
282 // init libswresample context
283 pan->swr = swr_alloc_set_opts(pan->swr,
284 pan->out_channel_layout, link->format, link->sample_rate,
285 link->channel_layout, link->format, link->sample_rate,
288 return AVERROR(ENOMEM);
290 // gains are pure, init the channel mapping
291 if (pan->pure_gains) {
293 // get channel map from the pure gains
294 for (i = 0; i < pan->nb_output_channels; i++) {
296 for (j = 0; j < pan->nb_input_channels; j++) {
297 if (pan->gain[i][j]) {
302 pan->channel_map[i] = ch_id;
305 av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
306 av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
307 swr_set_channel_mapping(pan->swr, pan->channel_map);
310 for (i = 0; i < pan->nb_output_channels; i++) {
311 if (!((pan->need_renorm >> i) & 1))
314 for (j = 0; j < pan->nb_input_channels; j++)
315 t += pan->gain[i][j];
316 if (t > -1E-5 && t < 1E-5) {
317 // t is almost 0 but not exactly, this is probably a mistake
319 av_log(ctx, AV_LOG_WARNING,
320 "Degenerate coefficients while renormalizing\n");
323 for (j = 0; j < pan->nb_input_channels; j++)
324 pan->gain[i][j] /= t;
326 av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
327 av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
328 swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
331 r = swr_init(pan->swr);
336 for (i = 0; i < pan->nb_output_channels; i++) {
338 for (j = 0; j < pan->nb_input_channels; j++) {
339 r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
340 j ? " + " : "", pan->gain[i][j], j);
341 cur += FFMIN(buf + sizeof(buf) - cur, r);
343 av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
345 // add channel mapping summary if possible
346 if (pan->pure_gains) {
347 av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
348 for (i = 0; i < pan->nb_output_channels; i++)
349 if (pan->channel_map[i] < 0)
350 av_log(ctx, AV_LOG_INFO, " M");
352 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
353 av_log(ctx, AV_LOG_INFO, "\n");
359 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
362 int n = insamples->nb_samples;
363 AVFilterLink *const outlink = inlink->dst->outputs[0];
364 AVFrame *outsamples = ff_get_audio_buffer(outlink, n);
365 PanContext *pan = inlink->dst->priv;
368 return AVERROR(ENOMEM);
369 swr_convert(pan->swr, outsamples->data, n, (void *)insamples->data, n);
370 av_frame_copy_props(outsamples, insamples);
371 outsamples->channel_layout = outlink->channel_layout;
372 av_frame_set_channels(outsamples, outlink->channels);
374 ret = ff_filter_frame(outlink, outsamples);
375 av_frame_free(&insamples);
379 static av_cold void uninit(AVFilterContext *ctx)
381 PanContext *pan = ctx->priv;
385 #define OFFSET(x) offsetof(PanContext, x)
387 static const AVOption pan_options[] = {
388 { "args", NULL, OFFSET(args), AV_OPT_TYPE_STRING, { .str = NULL }, CHAR_MIN, CHAR_MAX, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
392 AVFILTER_DEFINE_CLASS(pan);
395 static const AVFilterPad pan_inputs[] = {
398 .type = AVMEDIA_TYPE_AUDIO,
399 .config_props = config_props,
400 .filter_frame = filter_frame,
405 static const AVFilterPad pan_outputs[] = {
408 .type = AVMEDIA_TYPE_AUDIO,
413 AVFilter avfilter_af_pan = {
415 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
416 .priv_size = sizeof(PanContext),
417 .priv_class = &pan_class,
420 .query_formats = query_formats,
421 .inputs = pan_inputs,
422 .outputs = pan_outputs,