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 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/opt.h"
33 #include "libswresample/swresample.h"
36 #define MAX_CHANNELS 63
38 typedef struct PanContext {
39 int64_t out_channel_layout;
41 double d[MAX_CHANNELS][MAX_CHANNELS];
42 // i is 1:7:8 fixed-point, i.e. in [-128*256; +128*256[
43 int i[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, void *opaque)
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;
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 pan->out_channel_layout = av_get_channel_layout(arg);
117 if (!pan->out_channel_layout) {
118 av_log(ctx, AV_LOG_ERROR, "Unknown channel layout \"%s\"\n", arg);
119 return AVERROR(EINVAL);
121 pan->nb_output_channels = av_get_channel_layout_nb_channels(pan->out_channel_layout);
123 /* parse channel specifications */
124 while ((arg = arg0 = av_strtok(NULL, ":", &tokenizer))) {
126 if (parse_channel_name(&arg, &out_ch_id, &named)) {
127 av_log(ctx, AV_LOG_ERROR,
128 "Expected out channel name, got \"%.8s\"\n", arg);
129 return AVERROR(EINVAL);
132 if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
133 av_log(ctx, AV_LOG_ERROR,
134 "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
135 return 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 return AVERROR(EINVAL);
150 } else if (*arg == '<') {
151 pan->need_renorm |= (int64_t)1 << out_ch_id;
154 av_log(ctx, AV_LOG_ERROR,
155 "Syntax error after channel name in \"%.8s\"\n", arg0);
156 return AVERROR(EINVAL);
161 if (sscanf(arg, " %lf %n* %n", &gain, &len, &len))
163 if (parse_channel_name(&arg, &in_ch_id, &named)){
164 av_log(ctx, AV_LOG_ERROR,
165 "Expected in channel name, got \"%.8s\"\n", arg);
166 return AVERROR(EINVAL);
168 nb_in_channels[named]++;
169 if (nb_in_channels[!named]) {
170 av_log(ctx, AV_LOG_ERROR,
171 "Can not mix named and numbered channels\n");
172 return AVERROR(EINVAL);
174 pan->gain.d[out_ch_id][in_ch_id] = gain;
178 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
179 return AVERROR(EINVAL);
185 pan->need_renumber = !!nb_in_channels[1];
191 static int are_gains_pure(const PanContext *pan)
195 for (i = 0; i < MAX_CHANNELS; i++) {
198 for (j = 0; j < MAX_CHANNELS; j++) {
199 double gain = pan->gain.d[i][j];
201 /* channel mapping is effective only if 0% or 100% of a channel is
203 if (gain != 0. && gain != 1.)
205 /* ...and if the output channel is only composed of one input */
206 if (gain && nb_gain++)
213 static int query_formats(AVFilterContext *ctx)
215 PanContext *pan = ctx->priv;
216 AVFilterLink *inlink = ctx->inputs[0];
217 AVFilterLink *outlink = ctx->outputs[0];
218 AVFilterFormats *formats;
220 pan->pure_gains = are_gains_pure(pan);
221 /* libswr supports any sample and packing formats */
222 avfilter_set_common_sample_formats(ctx, avfilter_make_all_formats(AVMEDIA_TYPE_AUDIO));
223 avfilter_set_common_packing_formats(ctx, avfilter_make_all_packing_formats());
225 // inlink supports any channel layout
226 formats = avfilter_make_all_channel_layouts();
227 avfilter_formats_ref(formats, &inlink->out_chlayouts);
229 // outlink supports only requested output channel layout
231 avfilter_add_format(&formats, pan->out_channel_layout);
232 avfilter_formats_ref(formats, &outlink->in_chlayouts);
236 static int config_props(AVFilterLink *link)
238 AVFilterContext *ctx = link->dst;
239 PanContext *pan = ctx->priv;
240 char buf[1024], *cur;
244 pan->nb_input_channels = av_get_channel_layout_nb_channels(link->channel_layout);
245 if (pan->need_renumber) {
246 // input channels were given by their name: renumber them
247 for (i = j = 0; i < MAX_CHANNELS; i++) {
248 if ((link->channel_layout >> i) & 1) {
249 for (k = 0; k < pan->nb_output_channels; k++)
250 pan->gain.d[k][j] = pan->gain.d[k][i];
256 // sanity check; can't be done in query_formats since the inlink
257 // channel layout is unknown at that time
258 if (pan->nb_input_channels > SWR_CH_MAX ||
259 pan->nb_output_channels > SWR_CH_MAX) {
260 av_log(ctx, AV_LOG_ERROR,
261 "libswresample support a maximum of %d channels. "
262 "Feel free to ask for a higher limit.\n", SWR_CH_MAX);
263 return AVERROR_PATCHWELCOME;
266 // init libswresample context
267 pan->swr = swr_alloc_set_opts(pan->swr,
268 pan->out_channel_layout, link->format, link->sample_rate,
269 link->channel_layout, link->format, link->sample_rate,
272 return AVERROR(ENOMEM);
274 // gains are pure, init the channel mapping
275 if (pan->pure_gains) {
277 // get channel map from the pure gains
278 for (i = 0; i < pan->nb_output_channels; i++) {
280 for (j = 0; j < pan->nb_input_channels; j++) {
281 if (pan->gain.d[i][j]) {
286 pan->channel_map[i] = ch_id;
289 av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
290 av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
291 swr_set_channel_mapping(pan->swr, pan->channel_map);
294 for (i = 0; i < pan->nb_output_channels; i++) {
295 if (!((pan->need_renorm >> i) & 1))
298 for (j = 0; j < pan->nb_input_channels; j++)
299 t += pan->gain.d[i][j];
300 if (t > -1E-5 && t < 1E-5) {
301 // t is almost 0 but not exactly, this is probably a mistake
303 av_log(ctx, AV_LOG_WARNING,
304 "Degenerate coefficients while renormalizing\n");
307 for (j = 0; j < pan->nb_input_channels; j++)
308 pan->gain.d[i][j] /= t;
310 av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
311 av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
312 swr_set_matrix(pan->swr, pan->gain.d[0],
313 pan->gain.d[1] - pan->gain.d[0]);
316 r = swr_init(pan->swr);
321 for (i = 0; i < pan->nb_output_channels; i++) {
323 for (j = 0; j < pan->nb_input_channels; j++) {
324 r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
325 j ? " + " : "", pan->gain.d[i][j], j);
326 cur += FFMIN(buf + sizeof(buf) - cur, r);
328 av_log(ctx, AV_LOG_INFO, "o%d = %s\n", i, buf);
330 // add channel mapping summary if possible
331 if (pan->pure_gains) {
332 av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
333 for (i = 0; i < pan->nb_output_channels; i++)
334 if (pan->channel_map[i] < 0)
335 av_log(ctx, AV_LOG_INFO, " M");
337 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
338 av_log(ctx, AV_LOG_INFO, "\n");
341 // convert to integer
342 for (i = 0; i < pan->nb_output_channels; i++) {
343 for (j = 0; j < pan->nb_input_channels; j++) {
344 if (pan->gain.d[i][j] < -128 || pan->gain.d[i][j] > 128)
345 av_log(ctx, AV_LOG_WARNING,
346 "Gain #%d->#%d too large, clamped\n", j, i);
347 pan->gain.i[i][j] = av_clipf(pan->gain.d[i][j], -128, 128) * 256.0;
353 static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *insamples)
355 int n = insamples->audio->nb_samples;
356 AVFilterLink *const outlink = inlink->dst->outputs[0];
357 AVFilterBufferRef *outsamples = avfilter_get_audio_buffer(outlink, AV_PERM_WRITE, n);
358 PanContext *pan = inlink->dst->priv;
360 swr_convert(pan->swr, outsamples->data, n, (void *)insamples->data, n);
361 avfilter_copy_buffer_ref_props(outsamples, insamples);
362 outsamples->audio->channel_layout = outlink->channel_layout;
363 outsamples->audio->planar = outlink->planar;
365 avfilter_filter_samples(outlink, outsamples);
366 avfilter_unref_buffer(insamples);
369 static av_cold void uninit(AVFilterContext *ctx)
371 PanContext *pan = ctx->priv;
375 AVFilter avfilter_af_pan = {
377 .description = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
378 .priv_size = sizeof(PanContext),
381 .query_formats = query_formats,
383 .inputs = (const AVFilterPad[]) {
385 .type = AVMEDIA_TYPE_AUDIO,
386 .config_props = config_props,
387 .filter_samples = filter_samples,
388 .min_perms = AV_PERM_READ, },
391 .outputs = (const AVFilterPad[]) {
393 .type = AVMEDIA_TYPE_AUDIO, },