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 {
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 ret = AVERROR(EINVAL);
131 if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
132 av_log(ctx, AV_LOG_ERROR,
133 "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
134 ret = AVERROR(EINVAL);
137 /* get the channel number in the output channel layout:
138 * out_channel_layout & ((1 << out_ch_id) - 1) are all the
139 * channels that come before out_ch_id,
140 * so their count is the index of out_ch_id */
141 out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
143 if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
144 av_log(ctx, AV_LOG_ERROR,
145 "Invalid out channel name \"%.8s\"\n", arg0);
146 ret = AVERROR(EINVAL);
152 } else if (*arg == '<') {
153 pan->need_renorm |= (int64_t)1 << out_ch_id;
156 av_log(ctx, AV_LOG_ERROR,
157 "Syntax error after channel name in \"%.8s\"\n", arg0);
158 ret = AVERROR(EINVAL);
164 if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
166 if (parse_channel_name(&arg, &in_ch_id, &named)){
167 av_log(ctx, AV_LOG_ERROR,
168 "Expected in channel name, got \"%.8s\"\n", arg);
169 ret = AVERROR(EINVAL);
172 nb_in_channels[named]++;
173 if (nb_in_channels[!named]) {
174 av_log(ctx, AV_LOG_ERROR,
175 "Can not mix named and numbered channels\n");
176 ret = AVERROR(EINVAL);
179 pan->gain[out_ch_id][in_ch_id] = gain;
184 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
185 ret = AVERROR(EINVAL);
191 pan->need_renumber = !!nb_in_channels[1];
199 static int are_gains_pure(const PanContext *pan)
203 for (i = 0; i < MAX_CHANNELS; i++) {
206 for (j = 0; j < MAX_CHANNELS; j++) {
207 double gain = pan->gain[i][j];
209 /* channel mapping is effective only if 0% or 100% of a channel is
211 if (gain != 0. && gain != 1.)
213 /* ...and if the output channel is only composed of one input */
214 if (gain && nb_gain++)
221 static int query_formats(AVFilterContext *ctx)
223 PanContext *pan = ctx->priv;
224 AVFilterLink *inlink = ctx->inputs[0];
225 AVFilterLink *outlink = ctx->outputs[0];
226 AVFilterFormats *formats = NULL;
227 AVFilterChannelLayouts *layouts;
229 pan->pure_gains = are_gains_pure(pan);
230 /* libswr supports any sample and packing formats */
231 ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
233 formats = ff_all_samplerates();
235 return AVERROR(ENOMEM);
236 ff_set_common_samplerates(ctx, formats);
238 // inlink supports any channel layout
239 layouts = ff_all_channel_layouts();
240 ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
242 // outlink supports only requested output channel layout
244 ff_add_channel_layout(&layouts, pan->out_channel_layout);
245 ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
249 static int config_props(AVFilterLink *link)
251 AVFilterContext *ctx = link->dst;
252 PanContext *pan = ctx->priv;
253 char buf[1024], *cur;
257 pan->nb_input_channels = av_get_channel_layout_nb_channels(link->channel_layout);
258 if (pan->need_renumber) {
259 // input channels were given by their name: renumber them
260 for (i = j = 0; i < MAX_CHANNELS; i++) {
261 if ((link->channel_layout >> i) & 1) {
262 for (k = 0; k < pan->nb_output_channels; k++)
263 pan->gain[k][j] = pan->gain[k][i];
269 // sanity check; can't be done in query_formats since the inlink
270 // channel layout is unknown at that time
271 if (pan->nb_input_channels > SWR_CH_MAX ||
272 pan->nb_output_channels > SWR_CH_MAX) {
273 av_log(ctx, AV_LOG_ERROR,
274 "libswresample support a maximum of %d channels. "
275 "Feel free to ask for a higher limit.\n", SWR_CH_MAX);
276 return AVERROR_PATCHWELCOME;
279 // init libswresample context
280 pan->swr = swr_alloc_set_opts(pan->swr,
281 pan->out_channel_layout, link->format, link->sample_rate,
282 link->channel_layout, link->format, link->sample_rate,
285 return AVERROR(ENOMEM);
287 // gains are pure, init the channel mapping
288 if (pan->pure_gains) {
290 // get channel map from the pure gains
291 for (i = 0; i < pan->nb_output_channels; i++) {
293 for (j = 0; j < pan->nb_input_channels; j++) {
294 if (pan->gain[i][j]) {
299 pan->channel_map[i] = ch_id;
302 av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
303 av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
304 swr_set_channel_mapping(pan->swr, pan->channel_map);
307 for (i = 0; i < pan->nb_output_channels; i++) {
308 if (!((pan->need_renorm >> i) & 1))
311 for (j = 0; j < pan->nb_input_channels; j++)
312 t += pan->gain[i][j];
313 if (t > -1E-5 && t < 1E-5) {
314 // t is almost 0 but not exactly, this is probably a mistake
316 av_log(ctx, AV_LOG_WARNING,
317 "Degenerate coefficients while renormalizing\n");
320 for (j = 0; j < pan->nb_input_channels; j++)
321 pan->gain[i][j] /= t;
323 av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
324 av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
325 swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
328 r = swr_init(pan->swr);
333 for (i = 0; i < pan->nb_output_channels; i++) {
335 for (j = 0; j < pan->nb_input_channels; j++) {
336 r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
337 j ? " + " : "", pan->gain[i][j], j);
338 cur += FFMIN(buf + sizeof(buf) - cur, r);
340 av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
342 // add channel mapping summary if possible
343 if (pan->pure_gains) {
344 av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
345 for (i = 0; i < pan->nb_output_channels; i++)
346 if (pan->channel_map[i] < 0)
347 av_log(ctx, AV_LOG_INFO, " M");
349 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
350 av_log(ctx, AV_LOG_INFO, "\n");
356 static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
359 int n = insamples->nb_samples;
360 AVFilterLink *const outlink = inlink->dst->outputs[0];
361 AVFrame *outsamples = ff_get_audio_buffer(outlink, n);
362 PanContext *pan = inlink->dst->priv;
364 swr_convert(pan->swr, outsamples->data, n, (void *)insamples->data, n);
365 av_frame_copy_props(outsamples, insamples);
366 outsamples->channel_layout = outlink->channel_layout;
367 av_frame_set_channels(outsamples, outlink->channels);
369 ret = ff_filter_frame(outlink, outsamples);
370 av_frame_free(&insamples);
374 static av_cold void uninit(AVFilterContext *ctx)
376 PanContext *pan = ctx->priv;
380 static const AVFilterPad pan_inputs[] = {
383 .type = AVMEDIA_TYPE_AUDIO,
384 .config_props = config_props,
385 .filter_frame = filter_frame,
390 static const AVFilterPad pan_outputs[] = {
393 .type = AVMEDIA_TYPE_AUDIO,
398 AVFilter avfilter_af_pan = {
400 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
401 .priv_size = sizeof(PanContext),
404 .query_formats = query_formats,
405 .inputs = pan_inputs,
406 .outputs = pan_outputs,