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