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/audioconvert.h"
32 #include "libavutil/avstring.h"
33 #include "libavutil/opt.h"
34 #include "libswresample/swresample.h"
40 #define MAX_CHANNELS 63
42 typedef struct PanContext {
43 int64_t out_channel_layout;
44 double gain[MAX_CHANNELS][MAX_CHANNELS];
47 int nb_input_channels;
48 int nb_output_channels;
51 /* channel mapping specific */
52 int channel_map[SWR_CH_MAX];
53 struct SwrContext *swr;
56 static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
59 int len, i, channel_id = 0;
60 int64_t layout, layout0;
62 /* try to parse a channel name, e.g. "FL" */
63 if (sscanf(*arg, "%7[A-Z]%n", buf, &len)) {
64 layout0 = layout = av_get_channel_layout(buf);
65 /* channel_id <- first set bit in layout */
66 for (i = 32; i > 0; i >>= 1) {
67 if (layout >= (int64_t)1 << i) {
72 /* reject layouts that are not a single channel */
73 if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
74 return AVERROR(EINVAL);
75 *rchannel = channel_id;
80 /* try to parse a channel number, e.g. "c2" */
81 if (sscanf(*arg, "c%d%n", &channel_id, &len) &&
82 channel_id >= 0 && channel_id < MAX_CHANNELS) {
83 *rchannel = channel_id;
88 return AVERROR(EINVAL);
91 static void skip_spaces(char **arg)
95 sscanf(*arg, " %n", &len);
99 static av_cold int init(AVFilterContext *ctx, const char *args0)
101 PanContext *const pan = ctx->priv;
102 char *arg, *arg0, *tokenizer, *args = av_strdup(args0);
103 int out_ch_id, in_ch_id, len, named, ret;
104 int nb_in_channels[2] = { 0, 0 }; // number of unnamed and named input channels
108 av_log(ctx, AV_LOG_ERROR,
109 "pan filter needs a channel layout and a set "
110 "of channels definitions as parameter\n");
111 return AVERROR(EINVAL);
114 return AVERROR(ENOMEM);
115 arg = av_strtok(args, ":", &tokenizer);
116 ret = ff_parse_channel_layout(&pan->out_channel_layout, arg, ctx);
119 pan->nb_output_channels = av_get_channel_layout_nb_channels(pan->out_channel_layout);
121 /* parse channel specifications */
122 while ((arg = arg0 = av_strtok(NULL, ":", &tokenizer))) {
124 if (parse_channel_name(&arg, &out_ch_id, &named)) {
125 av_log(ctx, AV_LOG_ERROR,
126 "Expected out channel name, got \"%.8s\"\n", arg);
127 return AVERROR(EINVAL);
130 if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
131 av_log(ctx, AV_LOG_ERROR,
132 "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
133 return AVERROR(EINVAL);
135 /* get the channel number in the output channel layout:
136 * out_channel_layout & ((1 << out_ch_id) - 1) are all the
137 * channels that come before out_ch_id,
138 * so their count is the index of out_ch_id */
139 out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
141 if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
142 av_log(ctx, AV_LOG_ERROR,
143 "Invalid out channel name \"%.8s\"\n", arg0);
144 return AVERROR(EINVAL);
149 } else if (*arg == '<') {
150 pan->need_renorm |= (int64_t)1 << out_ch_id;
153 av_log(ctx, AV_LOG_ERROR,
154 "Syntax error after channel name in \"%.8s\"\n", arg0);
155 return AVERROR(EINVAL);
160 if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
162 if (parse_channel_name(&arg, &in_ch_id, &named)){
163 av_log(ctx, AV_LOG_ERROR,
164 "Expected in channel name, got \"%.8s\"\n", arg);
165 return AVERROR(EINVAL);
167 nb_in_channels[named]++;
168 if (nb_in_channels[!named]) {
169 av_log(ctx, AV_LOG_ERROR,
170 "Can not mix named and numbered channels\n");
171 return AVERROR(EINVAL);
173 pan->gain[out_ch_id][in_ch_id] = gain;
178 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
179 return AVERROR(EINVAL);
184 pan->need_renumber = !!nb_in_channels[1];
190 static int are_gains_pure(const PanContext *pan)
194 for (i = 0; i < MAX_CHANNELS; i++) {
197 for (j = 0; j < MAX_CHANNELS; j++) {
198 double gain = pan->gain[i][j];
200 /* channel mapping is effective only if 0% or 100% of a channel is
202 if (gain != 0. && gain != 1.)
204 /* ...and if the output channel is only composed of one input */
205 if (gain && nb_gain++)
212 static int query_formats(AVFilterContext *ctx)
214 PanContext *pan = ctx->priv;
215 AVFilterLink *inlink = ctx->inputs[0];
216 AVFilterLink *outlink = ctx->outputs[0];
217 AVFilterFormats *formats = NULL;
218 AVFilterChannelLayouts *layouts;
220 pan->pure_gains = are_gains_pure(pan);
221 /* libswr supports any sample and packing formats */
222 ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
224 formats = ff_all_samplerates();
226 return AVERROR(ENOMEM);
227 ff_set_common_samplerates(ctx, formats);
229 // inlink supports any channel layout
230 layouts = ff_all_channel_layouts();
231 ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
233 // outlink supports only requested output channel layout
235 ff_add_channel_layout(&layouts, pan->out_channel_layout);
236 ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
240 static int config_props(AVFilterLink *link)
242 AVFilterContext *ctx = link->dst;
243 PanContext *pan = ctx->priv;
244 char buf[1024], *cur;
248 pan->nb_input_channels = av_get_channel_layout_nb_channels(link->channel_layout);
249 if (pan->need_renumber) {
250 // input channels were given by their name: renumber them
251 for (i = j = 0; i < MAX_CHANNELS; i++) {
252 if ((link->channel_layout >> i) & 1) {
253 for (k = 0; k < pan->nb_output_channels; k++)
254 pan->gain[k][j] = pan->gain[k][i];
260 // sanity check; can't be done in query_formats since the inlink
261 // channel layout is unknown at that time
262 if (pan->nb_input_channels > SWR_CH_MAX ||
263 pan->nb_output_channels > SWR_CH_MAX) {
264 av_log(ctx, AV_LOG_ERROR,
265 "libswresample support a maximum of %d channels. "
266 "Feel free to ask for a higher limit.\n", SWR_CH_MAX);
267 return AVERROR_PATCHWELCOME;
270 // init libswresample context
271 pan->swr = swr_alloc_set_opts(pan->swr,
272 pan->out_channel_layout, link->format, link->sample_rate,
273 link->channel_layout, link->format, link->sample_rate,
276 return AVERROR(ENOMEM);
278 // gains are pure, init the channel mapping
279 if (pan->pure_gains) {
281 // get channel map from the pure gains
282 for (i = 0; i < pan->nb_output_channels; i++) {
284 for (j = 0; j < pan->nb_input_channels; j++) {
285 if (pan->gain[i][j]) {
290 pan->channel_map[i] = ch_id;
293 av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
294 av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
295 swr_set_channel_mapping(pan->swr, pan->channel_map);
298 for (i = 0; i < pan->nb_output_channels; i++) {
299 if (!((pan->need_renorm >> i) & 1))
302 for (j = 0; j < pan->nb_input_channels; j++)
303 t += pan->gain[i][j];
304 if (t > -1E-5 && t < 1E-5) {
305 // t is almost 0 but not exactly, this is probably a mistake
307 av_log(ctx, AV_LOG_WARNING,
308 "Degenerate coefficients while renormalizing\n");
311 for (j = 0; j < pan->nb_input_channels; j++)
312 pan->gain[i][j] /= t;
314 av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
315 av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
316 swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
319 r = swr_init(pan->swr);
324 for (i = 0; i < pan->nb_output_channels; i++) {
326 for (j = 0; j < pan->nb_input_channels; j++) {
327 r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
328 j ? " + " : "", pan->gain[i][j], j);
329 cur += FFMIN(buf + sizeof(buf) - cur, r);
331 av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
333 // add channel mapping summary if possible
334 if (pan->pure_gains) {
335 av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
336 for (i = 0; i < pan->nb_output_channels; i++)
337 if (pan->channel_map[i] < 0)
338 av_log(ctx, AV_LOG_INFO, " M");
340 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
341 av_log(ctx, AV_LOG_INFO, "\n");
347 static int filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
350 int n = insamples->audio->nb_samples;
351 AVFilterLink *const outlink = inlink->dst->outputs[0];
352 AVFilterBufferRef *outsamples = ff_get_audio_buffer(outlink, AV_PERM_WRITE, n);
353 PanContext *pan = inlink->dst->priv;
355 swr_convert(pan->swr, outsamples->data, n, (void *)insamples->data, n);
356 avfilter_copy_buffer_ref_props(outsamples, insamples);
357 outsamples->audio->channel_layout = outlink->channel_layout;
359 ret = ff_filter_samples(outlink, outsamples);
360 avfilter_unref_buffer(insamples);
364 static av_cold void uninit(AVFilterContext *ctx)
366 PanContext *pan = ctx->priv;
370 AVFilter avfilter_af_pan = {
372 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
373 .priv_size = sizeof(PanContext),
376 .query_formats = query_formats,
378 .inputs = (const AVFilterPad[]) {
380 .type = AVMEDIA_TYPE_AUDIO,
381 .config_props = config_props,
382 .filter_samples = filter_samples,
383 .min_perms = AV_PERM_READ, },
386 .outputs = (const AVFilterPad[]) {
388 .type = AVMEDIA_TYPE_AUDIO, },