blob: a746006f7107feb1712b56a6f8c98ff29bba8e8e
| 1 | /* |
| 2 | * Copyright (c) 2015 The FFmpeg Project |
| 3 | * |
| 4 | * This file is part of FFmpeg. |
| 5 | * |
| 6 | * FFmpeg is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public |
| 8 | * License as published by the Free Software Foundation; either |
| 9 | * version 2.1 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * FFmpeg is distributed in the hope that it will be useful, |
| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with FFmpeg; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 19 | */ |
| 20 | |
| 21 | #include "libavutil/channel_layout.h" |
| 22 | #include "libavutil/opt.h" |
| 23 | #include "avfilter.h" |
| 24 | #include "audio.h" |
| 25 | #include "formats.h" |
| 26 | |
| 27 | typedef struct ExtraStereoContext { |
| 28 | const AVClass *class; |
| 29 | float mult; |
| 30 | int clip; |
| 31 | } ExtraStereoContext; |
| 32 | |
| 33 | #define OFFSET(x) offsetof(ExtraStereoContext, x) |
| 34 | #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM |
| 35 | |
| 36 | static const AVOption extrastereo_options[] = { |
| 37 | { "m", "set the difference coefficient", OFFSET(mult), AV_OPT_TYPE_FLOAT, {.dbl=2.5}, -10, 10, A }, |
| 38 | { "c", "enable clipping", OFFSET(clip), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, A }, |
| 39 | { NULL } |
| 40 | }; |
| 41 | |
| 42 | AVFILTER_DEFINE_CLASS(extrastereo); |
| 43 | |
| 44 | static int query_formats(AVFilterContext *ctx) |
| 45 | { |
| 46 | AVFilterFormats *formats = NULL; |
| 47 | AVFilterChannelLayouts *layout = NULL; |
| 48 | int ret; |
| 49 | |
| 50 | if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_FLT )) < 0 || |
| 51 | (ret = ff_set_common_formats (ctx , formats )) < 0 || |
| 52 | (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 || |
| 53 | (ret = ff_set_common_channel_layouts (ctx , layout )) < 0) |
| 54 | return ret; |
| 55 | |
| 56 | formats = ff_all_samplerates(); |
| 57 | return ff_set_common_samplerates(ctx, formats); |
| 58 | } |
| 59 | |
| 60 | static int filter_frame(AVFilterLink *inlink, AVFrame *in) |
| 61 | { |
| 62 | AVFilterContext *ctx = inlink->dst; |
| 63 | AVFilterLink *outlink = ctx->outputs[0]; |
| 64 | ExtraStereoContext *s = ctx->priv; |
| 65 | const float *src = (const float *)in->data[0]; |
| 66 | const float mult = s->mult; |
| 67 | AVFrame *out; |
| 68 | float *dst; |
| 69 | int n; |
| 70 | |
| 71 | if (av_frame_is_writable(in)) { |
| 72 | out = in; |
| 73 | } else { |
| 74 | out = ff_get_audio_buffer(inlink, in->nb_samples); |
| 75 | if (!out) { |
| 76 | av_frame_free(&in); |
| 77 | return AVERROR(ENOMEM); |
| 78 | } |
| 79 | av_frame_copy_props(out, in); |
| 80 | } |
| 81 | dst = (float *)out->data[0]; |
| 82 | |
| 83 | for (n = 0; n < in->nb_samples; n++) { |
| 84 | float average, left, right; |
| 85 | |
| 86 | left = src[n * 2 ]; |
| 87 | right = src[n * 2 + 1]; |
| 88 | average = (left + right) / 2.; |
| 89 | left = average + mult * (left - average); |
| 90 | right = average + mult * (right - average); |
| 91 | |
| 92 | if (s->clip) { |
| 93 | dst[n * 2 ] = av_clipf(left, -1, 1); |
| 94 | dst[n * 2 + 1] = av_clipf(right, -1, 1); |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | if (out != in) |
| 99 | av_frame_free(&in); |
| 100 | return ff_filter_frame(outlink, out); |
| 101 | } |
| 102 | |
| 103 | static const AVFilterPad inputs[] = { |
| 104 | { |
| 105 | .name = "default", |
| 106 | .type = AVMEDIA_TYPE_AUDIO, |
| 107 | .filter_frame = filter_frame, |
| 108 | }, |
| 109 | { NULL } |
| 110 | }; |
| 111 | |
| 112 | static const AVFilterPad outputs[] = { |
| 113 | { |
| 114 | .name = "default", |
| 115 | .type = AVMEDIA_TYPE_AUDIO, |
| 116 | }, |
| 117 | { NULL } |
| 118 | }; |
| 119 | |
| 120 | AVFilter ff_af_extrastereo = { |
| 121 | .name = "extrastereo", |
| 122 | .description = NULL_IF_CONFIG_SMALL("Increase difference between stereo audio channels."), |
| 123 | .query_formats = query_formats, |
| 124 | .priv_size = sizeof(ExtraStereoContext), |
| 125 | .priv_class = &extrastereo_class, |
| 126 | .inputs = inputs, |
| 127 | .outputs = outputs, |
| 128 | }; |
| 129 |