summaryrefslogtreecommitdiffstats
path: root/libavfilter/af_pan.c
blob: 77ca5491672b821677365bd319df2354603c0af5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
/*
 * Copyright (c) 2002 Anders Johansson <ajh@atri.curtin.edu.au>
 * Copyright (c) 2011 Clément Bœsch <ubitux@gmail.com>
 * Copyright (c) 2011 Nicolas George <nicolas.george@normalesup.org>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * Audio panning filter (channels mixing)
 * Original code written by Anders Johansson for MPlayer,
 * reimplemented for FFmpeg.
 */

#include <stdio.h>
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/opt.h"
#include "libswresample/swresample.h"
#include "audio.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"

#define MAX_CHANNELS 63

typedef struct PanContext {
    int64_t out_channel_layout;
    double gain[MAX_CHANNELS][MAX_CHANNELS];
    int64_t need_renorm;
    int need_renumber;
    int nb_input_channels;
    int nb_output_channels;

    int pure_gains;
    /* channel mapping specific */
    int channel_map[SWR_CH_MAX];
    struct SwrContext *swr;
} PanContext;

static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
{
    char buf[8];
    int len, i, channel_id = 0;
    int64_t layout, layout0;

    /* try to parse a channel name, e.g. "FL" */
    if (sscanf(*arg, "%7[A-Z]%n", buf, &len)) {
        layout0 = layout = av_get_channel_layout(buf);
        /* channel_id <- first set bit in layout */
        for (i = 32; i > 0; i >>= 1) {
            if (layout >= (int64_t)1 << i) {
                channel_id += i;
                layout >>= i;
            }
        }
        /* reject layouts that are not a single channel */
        if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
            return AVERROR(EINVAL);
        *rchannel = channel_id;
        *rnamed = 1;
        *arg += len;
        return 0;
    }
    /* try to parse a channel number, e.g. "c2" */
    if (sscanf(*arg, "c%d%n", &channel_id, &len) &&
        channel_id >= 0 && channel_id < MAX_CHANNELS) {
        *rchannel = channel_id;
        *rnamed = 0;
        *arg += len;
        return 0;
    }
    return AVERROR(EINVAL);
}

static void skip_spaces(char **arg)
{
    int len = 0;

    sscanf(*arg, " %n", &len);
    *arg += len;
}

static av_cold int init(AVFilterContext *ctx, const char *args0)
{
    PanContext *const pan = ctx->priv;
    char *arg, *arg0, *tokenizer, *args = av_strdup(args0);
    int out_ch_id, in_ch_id, len, named, ret;
    int nb_in_channels[2] = { 0, 0 }; // number of unnamed and named input channels
    double gain;

    if (!args0) {
        av_log(ctx, AV_LOG_ERROR,
               "pan filter needs a channel layout and a set "
               "of channels definitions as parameter\n");
        return AVERROR(EINVAL);
    }
    if (!args)
        return AVERROR(ENOMEM);
    arg = av_strtok(args, ":", &tokenizer);
    ret = ff_parse_channel_layout(&pan->out_channel_layout, arg, ctx);
    if (ret < 0)
        goto fail;
    pan->nb_output_channels = av_get_channel_layout_nb_channels(pan->out_channel_layout);

    /* parse channel specifications */
    while ((arg = arg0 = av_strtok(NULL, ":", &tokenizer))) {
        /* channel name */
        if (parse_channel_name(&arg, &out_ch_id, &named)) {
            av_log(ctx, AV_LOG_ERROR,
                   "Expected out channel name, got \"%.8s\"\n", arg);
            ret = AVERROR(EINVAL);
            goto fail;
        }
        if (named) {
            if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
                av_log(ctx, AV_LOG_ERROR,
                       "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
                ret = AVERROR(EINVAL);
                goto fail;
            }
            /* get the channel number in the output channel layout:
             * out_channel_layout & ((1 << out_ch_id) - 1) are all the
             * channels that come before out_ch_id,
             * so their count is the index of out_ch_id */
            out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
        }
        if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
            av_log(ctx, AV_LOG_ERROR,
                   "Invalid out channel name \"%.8s\"\n", arg0);
            ret = AVERROR(EINVAL);
            goto fail;
        }
        skip_spaces(&arg);
        if (*arg == '=') {
            arg++;
        } else if (*arg == '<') {
            pan->need_renorm |= (int64_t)1 << out_ch_id;
            arg++;
        } else {
            av_log(ctx, AV_LOG_ERROR,
                   "Syntax error after channel name in \"%.8s\"\n", arg0);
            ret = AVERROR(EINVAL);
            goto fail;
        }
        /* gains */
        while (1) {
            gain = 1;
            if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
                arg += len;
            if (parse_channel_name(&arg, &in_ch_id, &named)){
                av_log(ctx, AV_LOG_ERROR,
                       "Expected in channel name, got \"%.8s\"\n", arg);
                 ret = AVERROR(EINVAL);
                 goto fail;
            }
            nb_in_channels[named]++;
            if (nb_in_channels[!named]) {
                av_log(ctx, AV_LOG_ERROR,
                       "Can not mix named and numbered channels\n");
                ret = AVERROR(EINVAL);
                goto fail;
            }
            pan->gain[out_ch_id][in_ch_id] = gain;
            skip_spaces(&arg);
            if (!*arg)
                break;
            if (*arg != '+') {
                av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
                ret = AVERROR(EINVAL);
                goto fail;
            }
            arg++;
        }
    }
    pan->need_renumber = !!nb_in_channels[1];

    ret = 0;
fail:
    av_free(args);
    return ret;
}

static int are_gains_pure(const PanContext *pan)
{
    int i, j;

    for (i = 0; i < MAX_CHANNELS; i++) {
        int nb_gain = 0;

        for (j = 0; j < MAX_CHANNELS; j++) {
            double gain = pan->gain[i][j];

            /* channel mapping is effective only if 0% or 100% of a channel is
             * selected... */
            if (gain != 0. && gain != 1.)
                return 0;
            /* ...and if the output channel is only composed of one input */
            if (gain && nb_gain++)
                return 0;
        }
    }
    return 1;
}

static int query_formats(AVFilterContext *ctx)
{
    PanContext *pan = ctx->priv;
    AVFilterLink *inlink  = ctx->inputs[0];
    AVFilterLink *outlink = ctx->outputs[0];
    AVFilterFormats *formats = NULL;
    AVFilterChannelLayouts *layouts;

    pan->pure_gains = are_gains_pure(pan);
    /* libswr supports any sample and packing formats */
    ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));

    formats = ff_all_samplerates();
    if (!formats)
        return AVERROR(ENOMEM);
    ff_set_common_samplerates(ctx, formats);

    // inlink supports any channel layout
    layouts = ff_all_channel_layouts();
    ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);

    // outlink supports only requested output channel layout
    layouts = NULL;
    ff_add_channel_layout(&layouts, pan->out_channel_layout);
    ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
    return 0;
}

static int config_props(AVFilterLink *link)
{
    AVFilterContext *ctx = link->dst;
    PanContext *pan = ctx->priv;
    char buf[1024], *cur;
    int i, j, k, r;
    double t;

    pan->nb_input_channels = av_get_channel_layout_nb_channels(link->channel_layout);
    if (pan->need_renumber) {
        // input channels were given by their name: renumber them
        for (i = j = 0; i < MAX_CHANNELS; i++) {
            if ((link->channel_layout >> i) & 1) {
                for (k = 0; k < pan->nb_output_channels; k++)
                    pan->gain[k][j] = pan->gain[k][i];
                j++;
            }
        }
    }

    // sanity check; can't be done in query_formats since the inlink
    // channel layout is unknown at that time
    if (pan->nb_input_channels > SWR_CH_MAX ||
        pan->nb_output_channels > SWR_CH_MAX) {
        av_log(ctx, AV_LOG_ERROR,
               "libswresample support a maximum of %d channels. "
               "Feel free to ask for a higher limit.\n", SWR_CH_MAX);
        return AVERROR_PATCHWELCOME;
    }

    // init libswresample context
    pan->swr = swr_alloc_set_opts(pan->swr,
                                  pan->out_channel_layout, link->format, link->sample_rate,
                                  link->channel_layout,    link->format, link->sample_rate,
                                  0, ctx);
    if (!pan->swr)
        return AVERROR(ENOMEM);

    // gains are pure, init the channel mapping
    if (pan->pure_gains) {

        // get channel map from the pure gains
        for (i = 0; i < pan->nb_output_channels; i++) {
            int ch_id = -1;
            for (j = 0; j < pan->nb_input_channels; j++) {
                if (pan->gain[i][j]) {
                    ch_id = j;
                    break;
                }
            }
            pan->channel_map[i] = ch_id;
        }

        av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
        av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
        swr_set_channel_mapping(pan->swr, pan->channel_map);
    } else {
        // renormalize
        for (i = 0; i < pan->nb_output_channels; i++) {
            if (!((pan->need_renorm >> i) & 1))
                continue;
            t = 0;
            for (j = 0; j < pan->nb_input_channels; j++)
                t += pan->gain[i][j];
            if (t > -1E-5 && t < 1E-5) {
                // t is almost 0 but not exactly, this is probably a mistake
                if (t)
                    av_log(ctx, AV_LOG_WARNING,
                           "Degenerate coefficients while renormalizing\n");
                continue;
            }
            for (j = 0; j < pan->nb_input_channels; j++)
                pan->gain[i][j] /= t;
        }
        av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
        av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
        swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
    }

    r = swr_init(pan->swr);
    if (r < 0)
        return r;

    // summary
    for (i = 0; i < pan->nb_output_channels; i++) {
        cur = buf;
        for (j = 0; j < pan->nb_input_channels; j++) {
            r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
                         j ? " + " : "", pan->gain[i][j], j);
            cur += FFMIN(buf + sizeof(buf) - cur, r);
        }
        av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
    }
    // add channel mapping summary if possible
    if (pan->pure_gains) {
        av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
        for (i = 0; i < pan->nb_output_channels; i++)
            if (pan->channel_map[i] < 0)
                av_log(ctx, AV_LOG_INFO, " M");
            else
                av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
        av_log(ctx, AV_LOG_INFO, "\n");
        return 0;
    }
    return 0;
}

static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *insamples)
{
    int ret;
    int n = insamples->audio->nb_samples;
    AVFilterLink *const outlink = inlink->dst->outputs[0];
    AVFilterBufferRef *outsamples = ff_get_audio_buffer(outlink, AV_PERM_WRITE, n);
    PanContext *pan = inlink->dst->priv;

    swr_convert(pan->swr, outsamples->data, n, (void *)insamples->data, n);
    avfilter_copy_buffer_ref_props(outsamples, insamples);
    outsamples->audio->channel_layout = outlink->channel_layout;
    outsamples->audio->channels       = outlink->channels;

    ret = ff_filter_frame(outlink, outsamples);
    avfilter_unref_buffer(insamples);
    return ret;
}

static av_cold void uninit(AVFilterContext *ctx)
{
    PanContext *pan = ctx->priv;
    swr_free(&pan->swr);
}

static const AVFilterPad pan_inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_AUDIO,
        .config_props = config_props,
        .filter_frame = filter_frame,
        .min_perms    = AV_PERM_READ,
    },
    { NULL }
};

static const AVFilterPad pan_outputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_AUDIO,
    },
    { NULL }
};

AVFilter avfilter_af_pan = {
    .name          = "pan",
    .description   = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
    .priv_size     = sizeof(PanContext),
    .init          = init,
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = pan_inputs,
    .outputs       = pan_outputs,
};
OpenPOWER on IntegriCloud