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  1. /*
  2.  * Copyright (c) 2002 Anders Johansson <ajh@atri.curtin.edu.au>
  3.  * Copyright (c) 2011 Clément Bœsch <u pkh me>
  4.  * Copyright (c) 2011 Nicolas George <nicolas.george@normalesup.org>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  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.
  12.  *
  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.
  17.  *
  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
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * Audio panning filter (channels mixing)
  26.  * Original code written by Anders Johansson for MPlayer,
  27.  * reimplemented for FFmpeg.
  28.  */
  29.  
  30. #include <stdio.h>
  31. #include "libavutil/avstring.h"
  32. #include "libavutil/channel_layout.h"
  33. #include "libavutil/opt.h"
  34. #include "libswresample/swresample.h"
  35. #include "audio.h"
  36. #include "avfilter.h"
  37. #include "formats.h"
  38. #include "internal.h"
  39.  
  40. #define MAX_CHANNELS 64
  41.  
  42. typedef struct PanContext {
  43.     const AVClass *class;
  44.     char *args;
  45.     int64_t out_channel_layout;
  46.     double gain[MAX_CHANNELS][MAX_CHANNELS];
  47.     int64_t need_renorm;
  48.     int need_renumber;
  49.     int nb_output_channels;
  50.  
  51.     int pure_gains;
  52.     /* channel mapping specific */
  53.     int channel_map[MAX_CHANNELS];
  54.     struct SwrContext *swr;
  55. } PanContext;
  56.  
  57. static void skip_spaces(char **arg)
  58. {
  59.     int len = 0;
  60.  
  61.     sscanf(*arg, " %n", &len);
  62.     *arg += len;
  63. }
  64.  
  65. static int parse_channel_name(char **arg, int *rchannel, int *rnamed)
  66. {
  67.     char buf[8];
  68.     int len, i, channel_id = 0;
  69.     int64_t layout, layout0;
  70.  
  71.     skip_spaces(arg);
  72.     /* try to parse a channel name, e.g. "FL" */
  73.     if (sscanf(*arg, "%7[A-Z]%n", buf, &len)) {
  74.         layout0 = layout = av_get_channel_layout(buf);
  75.         /* channel_id <- first set bit in layout */
  76.         for (i = 32; i > 0; i >>= 1) {
  77.             if (layout >= (int64_t)1 << i) {
  78.                 channel_id += i;
  79.                 layout >>= i;
  80.             }
  81.         }
  82.         /* reject layouts that are not a single channel */
  83.         if (channel_id >= MAX_CHANNELS || layout0 != (int64_t)1 << channel_id)
  84.             return AVERROR(EINVAL);
  85.         *rchannel = channel_id;
  86.         *rnamed = 1;
  87.         *arg += len;
  88.         return 0;
  89.     }
  90.     /* try to parse a channel number, e.g. "c2" */
  91.     if (sscanf(*arg, "c%d%n", &channel_id, &len) &&
  92.         channel_id >= 0 && channel_id < MAX_CHANNELS) {
  93.         *rchannel = channel_id;
  94.         *rnamed = 0;
  95.         *arg += len;
  96.         return 0;
  97.     }
  98.     return AVERROR(EINVAL);
  99. }
  100.  
  101. static av_cold int init(AVFilterContext *ctx)
  102. {
  103.     PanContext *const pan = ctx->priv;
  104.     char *arg, *arg0, *tokenizer, *args = av_strdup(pan->args);
  105.     int out_ch_id, in_ch_id, len, named, ret;
  106.     int nb_in_channels[2] = { 0, 0 }; // number of unnamed and named input channels
  107.     double gain;
  108.  
  109.     if (!pan->args) {
  110.         av_log(ctx, AV_LOG_ERROR,
  111.                "pan filter needs a channel layout and a set "
  112.                "of channels definitions as parameter\n");
  113.         return AVERROR(EINVAL);
  114.     }
  115.     if (!args)
  116.         return AVERROR(ENOMEM);
  117.     arg = av_strtok(args, "|", &tokenizer);
  118.     ret = ff_parse_channel_layout(&pan->out_channel_layout,
  119.                                   &pan->nb_output_channels, arg, ctx);
  120.     if (ret < 0)
  121.         goto fail;
  122.  
  123.     /* parse channel specifications */
  124.     while ((arg = arg0 = av_strtok(NULL, "|", &tokenizer))) {
  125.         /* channel name */
  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.             ret = AVERROR(EINVAL);
  130.             goto fail;
  131.         }
  132.         if (named) {
  133.             if (!((pan->out_channel_layout >> out_ch_id) & 1)) {
  134.                 av_log(ctx, AV_LOG_ERROR,
  135.                        "Channel \"%.8s\" does not exist in the chosen layout\n", arg0);
  136.                 ret = AVERROR(EINVAL);
  137.                 goto fail;
  138.             }
  139.             /* get the channel number in the output channel layout:
  140.              * out_channel_layout & ((1 << out_ch_id) - 1) are all the
  141.              * channels that come before out_ch_id,
  142.              * so their count is the index of out_ch_id */
  143.             out_ch_id = av_get_channel_layout_nb_channels(pan->out_channel_layout & (((int64_t)1 << out_ch_id) - 1));
  144.         }
  145.         if (out_ch_id < 0 || out_ch_id >= pan->nb_output_channels) {
  146.             av_log(ctx, AV_LOG_ERROR,
  147.                    "Invalid out channel name \"%.8s\"\n", arg0);
  148.             ret = AVERROR(EINVAL);
  149.             goto fail;
  150.         }
  151.         skip_spaces(&arg);
  152.         if (*arg == '=') {
  153.             arg++;
  154.         } else if (*arg == '<') {
  155.             pan->need_renorm |= (int64_t)1 << out_ch_id;
  156.             arg++;
  157.         } else {
  158.             av_log(ctx, AV_LOG_ERROR,
  159.                    "Syntax error after channel name in \"%.8s\"\n", arg0);
  160.             ret = AVERROR(EINVAL);
  161.             goto fail;
  162.         }
  163.         /* gains */
  164.         while (1) {
  165.             gain = 1;
  166.             if (sscanf(arg, "%lf%n *%n", &gain, &len, &len))
  167.                 arg += len;
  168.             if (parse_channel_name(&arg, &in_ch_id, &named)){
  169.                 av_log(ctx, AV_LOG_ERROR,
  170.                        "Expected in channel name, got \"%.8s\"\n", arg);
  171.                  ret = AVERROR(EINVAL);
  172.                  goto fail;
  173.             }
  174.             nb_in_channels[named]++;
  175.             if (nb_in_channels[!named]) {
  176.                 av_log(ctx, AV_LOG_ERROR,
  177.                        "Can not mix named and numbered channels\n");
  178.                 ret = AVERROR(EINVAL);
  179.                 goto fail;
  180.             }
  181.             pan->gain[out_ch_id][in_ch_id] = gain;
  182.             skip_spaces(&arg);
  183.             if (!*arg)
  184.                 break;
  185.             if (*arg != '+') {
  186.                 av_log(ctx, AV_LOG_ERROR, "Syntax error near \"%.8s\"\n", arg);
  187.                 ret = AVERROR(EINVAL);
  188.                 goto fail;
  189.             }
  190.             arg++;
  191.         }
  192.     }
  193.     pan->need_renumber = !!nb_in_channels[1];
  194.  
  195.     ret = 0;
  196. fail:
  197.     av_free(args);
  198.     return ret;
  199. }
  200.  
  201. static int are_gains_pure(const PanContext *pan)
  202. {
  203.     int i, j;
  204.  
  205.     for (i = 0; i < MAX_CHANNELS; i++) {
  206.         int nb_gain = 0;
  207.  
  208.         for (j = 0; j < MAX_CHANNELS; j++) {
  209.             double gain = pan->gain[i][j];
  210.  
  211.             /* channel mapping is effective only if 0% or 100% of a channel is
  212.              * selected... */
  213.             if (gain != 0. && gain != 1.)
  214.                 return 0;
  215.             /* ...and if the output channel is only composed of one input */
  216.             if (gain && nb_gain++)
  217.                 return 0;
  218.         }
  219.     }
  220.     return 1;
  221. }
  222.  
  223. static int query_formats(AVFilterContext *ctx)
  224. {
  225.     PanContext *pan = ctx->priv;
  226.     AVFilterLink *inlink  = ctx->inputs[0];
  227.     AVFilterLink *outlink = ctx->outputs[0];
  228.     AVFilterFormats *formats = NULL;
  229.     AVFilterChannelLayouts *layouts;
  230.  
  231.     pan->pure_gains = are_gains_pure(pan);
  232.     /* libswr supports any sample and packing formats */
  233.     ff_set_common_formats(ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
  234.  
  235.     formats = ff_all_samplerates();
  236.     if (!formats)
  237.         return AVERROR(ENOMEM);
  238.     ff_set_common_samplerates(ctx, formats);
  239.  
  240.     // inlink supports any channel layout
  241.     layouts = ff_all_channel_counts();
  242.     ff_channel_layouts_ref(layouts, &inlink->out_channel_layouts);
  243.  
  244.     // outlink supports only requested output channel layout
  245.     layouts = NULL;
  246.     ff_add_channel_layout(&layouts,
  247.                           pan->out_channel_layout ? pan->out_channel_layout :
  248.                           FF_COUNT2LAYOUT(pan->nb_output_channels));
  249.     ff_channel_layouts_ref(layouts, &outlink->in_channel_layouts);
  250.     return 0;
  251. }
  252.  
  253. static int config_props(AVFilterLink *link)
  254. {
  255.     AVFilterContext *ctx = link->dst;
  256.     PanContext *pan = ctx->priv;
  257.     char buf[1024], *cur;
  258.     int i, j, k, r;
  259.     double t;
  260.  
  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];
  267.                 j++;
  268.             }
  269.         }
  270.     }
  271.  
  272.     // sanity check; can't be done in query_formats since the inlink
  273.     // channel layout is unknown at that time
  274.     if (link->channels > MAX_CHANNELS ||
  275.         pan->nb_output_channels > MAX_CHANNELS) {
  276.         av_log(ctx, AV_LOG_ERROR,
  277.                "af_pan support a maximum of %d channels. "
  278.                "Feel free to ask for a higher limit.\n", MAX_CHANNELS);
  279.         return AVERROR_PATCHWELCOME;
  280.     }
  281.  
  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,
  286.                                   0, ctx);
  287.     if (!pan->swr)
  288.         return AVERROR(ENOMEM);
  289.     if (!link->channel_layout) {
  290.         if (av_opt_set_int(pan->swr, "ich", link->channels, 0) < 0)
  291.             return AVERROR(EINVAL);
  292.     }
  293.     if (!pan->out_channel_layout) {
  294.         if (av_opt_set_int(pan->swr, "och", pan->nb_output_channels, 0) < 0)
  295.             return AVERROR(EINVAL);
  296.     }
  297.  
  298.     // gains are pure, init the channel mapping
  299.     if (pan->pure_gains) {
  300.  
  301.         // get channel map from the pure gains
  302.         for (i = 0; i < pan->nb_output_channels; i++) {
  303.             int ch_id = -1;
  304.             for (j = 0; j < link->channels; j++) {
  305.                 if (pan->gain[i][j]) {
  306.                     ch_id = j;
  307.                     break;
  308.                 }
  309.             }
  310.             pan->channel_map[i] = ch_id;
  311.         }
  312.  
  313.         av_opt_set_int(pan->swr, "icl", pan->out_channel_layout, 0);
  314.         av_opt_set_int(pan->swr, "uch", pan->nb_output_channels, 0);
  315.         swr_set_channel_mapping(pan->swr, pan->channel_map);
  316.     } else {
  317.         // renormalize
  318.         for (i = 0; i < pan->nb_output_channels; i++) {
  319.             if (!((pan->need_renorm >> i) & 1))
  320.                 continue;
  321.             t = 0;
  322.             for (j = 0; j < link->channels; j++)
  323.                 t += pan->gain[i][j];
  324.             if (t > -1E-5 && t < 1E-5) {
  325.                 // t is almost 0 but not exactly, this is probably a mistake
  326.                 if (t)
  327.                     av_log(ctx, AV_LOG_WARNING,
  328.                            "Degenerate coefficients while renormalizing\n");
  329.                 continue;
  330.             }
  331.             for (j = 0; j < link->channels; j++)
  332.                 pan->gain[i][j] /= t;
  333.         }
  334.         av_opt_set_int(pan->swr, "icl", link->channel_layout, 0);
  335.         av_opt_set_int(pan->swr, "ocl", pan->out_channel_layout, 0);
  336.         swr_set_matrix(pan->swr, pan->gain[0], pan->gain[1] - pan->gain[0]);
  337.     }
  338.  
  339.     r = swr_init(pan->swr);
  340.     if (r < 0)
  341.         return r;
  342.  
  343.     // summary
  344.     for (i = 0; i < pan->nb_output_channels; i++) {
  345.         cur = buf;
  346.         for (j = 0; j < link->channels; j++) {
  347.             r = snprintf(cur, buf + sizeof(buf) - cur, "%s%.3g i%d",
  348.                          j ? " + " : "", pan->gain[i][j], j);
  349.             cur += FFMIN(buf + sizeof(buf) - cur, r);
  350.         }
  351.         av_log(ctx, AV_LOG_VERBOSE, "o%d = %s\n", i, buf);
  352.     }
  353.     // add channel mapping summary if possible
  354.     if (pan->pure_gains) {
  355.         av_log(ctx, AV_LOG_INFO, "Pure channel mapping detected:");
  356.         for (i = 0; i < pan->nb_output_channels; i++)
  357.             if (pan->channel_map[i] < 0)
  358.                 av_log(ctx, AV_LOG_INFO, " M");
  359.             else
  360.                 av_log(ctx, AV_LOG_INFO, " %d", pan->channel_map[i]);
  361.         av_log(ctx, AV_LOG_INFO, "\n");
  362.         return 0;
  363.     }
  364.     return 0;
  365. }
  366.  
  367. static int filter_frame(AVFilterLink *inlink, AVFrame *insamples)
  368. {
  369.     int ret;
  370.     int n = insamples->nb_samples;
  371.     AVFilterLink *const outlink = inlink->dst->outputs[0];
  372.     AVFrame *outsamples = ff_get_audio_buffer(outlink, n);
  373.     PanContext *pan = inlink->dst->priv;
  374.  
  375.     if (!outsamples)
  376.         return AVERROR(ENOMEM);
  377.     swr_convert(pan->swr, outsamples->extended_data, n,
  378.                 (void *)insamples->extended_data, n);
  379.     av_frame_copy_props(outsamples, insamples);
  380.     outsamples->channel_layout = outlink->channel_layout;
  381.     av_frame_set_channels(outsamples, outlink->channels);
  382.  
  383.     ret = ff_filter_frame(outlink, outsamples);
  384.     av_frame_free(&insamples);
  385.     return ret;
  386. }
  387.  
  388. static av_cold void uninit(AVFilterContext *ctx)
  389. {
  390.     PanContext *pan = ctx->priv;
  391.     swr_free(&pan->swr);
  392. }
  393.  
  394. #define OFFSET(x) offsetof(PanContext, x)
  395.  
  396. static const AVOption pan_options[] = {
  397.     { "args", NULL, OFFSET(args), AV_OPT_TYPE_STRING, { .str = NULL }, CHAR_MIN, CHAR_MAX, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_FILTERING_PARAM },
  398.     { NULL }
  399. };
  400.  
  401. AVFILTER_DEFINE_CLASS(pan);
  402.  
  403. static const AVFilterPad pan_inputs[] = {
  404.     {
  405.         .name         = "default",
  406.         .type         = AVMEDIA_TYPE_AUDIO,
  407.         .config_props = config_props,
  408.         .filter_frame = filter_frame,
  409.     },
  410.     { NULL }
  411. };
  412.  
  413. static const AVFilterPad pan_outputs[] = {
  414.     {
  415.         .name = "default",
  416.         .type = AVMEDIA_TYPE_AUDIO,
  417.     },
  418.     { NULL }
  419. };
  420.  
  421. AVFilter ff_af_pan = {
  422.     .name          = "pan",
  423.     .description   = NULL_IF_CONFIG_SMALL("Remix channels with coefficients (panning)."),
  424.     .priv_size     = sizeof(PanContext),
  425.     .priv_class    = &pan_class,
  426.     .init          = init,
  427.     .uninit        = uninit,
  428.     .query_formats = query_formats,
  429.     .inputs        = pan_inputs,
  430.     .outputs       = pan_outputs,
  431. };
  432.