| /* |
| * Copyright (c) 2015 The FFmpeg Project |
| * |
| * 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 |
| */ |
| |
| #include "libavutil/channel_layout.h" |
| #include "libavutil/opt.h" |
| #include "avfilter.h" |
| #include "audio.h" |
| #include "formats.h" |
| |
| typedef struct ExtraStereoContext { |
| const AVClass *class; |
| float mult; |
| int clip; |
| } ExtraStereoContext; |
| |
| #define OFFSET(x) offsetof(ExtraStereoContext, x) |
| #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM |
| |
| static const AVOption extrastereo_options[] = { |
| { "m", "set the difference coefficient", OFFSET(mult), AV_OPT_TYPE_FLOAT, {.dbl=2.5}, -10, 10, A }, |
| { "c", "enable clipping", OFFSET(clip), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, A }, |
| { NULL } |
| }; |
| |
| AVFILTER_DEFINE_CLASS(extrastereo); |
| |
| static int query_formats(AVFilterContext *ctx) |
| { |
| AVFilterFormats *formats = NULL; |
| AVFilterChannelLayouts *layout = NULL; |
| int ret; |
| |
| if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_FLT )) < 0 || |
| (ret = ff_set_common_formats (ctx , formats )) < 0 || |
| (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 || |
| (ret = ff_set_common_channel_layouts (ctx , layout )) < 0) |
| return ret; |
| |
| formats = ff_all_samplerates(); |
| return ff_set_common_samplerates(ctx, formats); |
| } |
| |
| static int filter_frame(AVFilterLink *inlink, AVFrame *in) |
| { |
| AVFilterContext *ctx = inlink->dst; |
| AVFilterLink *outlink = ctx->outputs[0]; |
| ExtraStereoContext *s = ctx->priv; |
| const float *src = (const float *)in->data[0]; |
| const float mult = s->mult; |
| AVFrame *out; |
| float *dst; |
| int n; |
| |
| if (av_frame_is_writable(in)) { |
| out = in; |
| } else { |
| out = ff_get_audio_buffer(inlink, in->nb_samples); |
| if (!out) { |
| av_frame_free(&in); |
| return AVERROR(ENOMEM); |
| } |
| av_frame_copy_props(out, in); |
| } |
| dst = (float *)out->data[0]; |
| |
| for (n = 0; n < in->nb_samples; n++) { |
| float average, left, right; |
| |
| left = src[n * 2 ]; |
| right = src[n * 2 + 1]; |
| average = (left + right) / 2.; |
| left = average + mult * (left - average); |
| right = average + mult * (right - average); |
| |
| if (s->clip) { |
| dst[n * 2 ] = av_clipf(left, -1, 1); |
| dst[n * 2 + 1] = av_clipf(right, -1, 1); |
| } |
| } |
| |
| if (out != in) |
| av_frame_free(&in); |
| return ff_filter_frame(outlink, out); |
| } |
| |
| static const AVFilterPad inputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_AUDIO, |
| .filter_frame = filter_frame, |
| }, |
| { NULL } |
| }; |
| |
| static const AVFilterPad outputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_AUDIO, |
| }, |
| { NULL } |
| }; |
| |
| AVFilter ff_af_extrastereo = { |
| .name = "extrastereo", |
| .description = NULL_IF_CONFIG_SMALL("Increase difference between stereo audio channels."), |
| .query_formats = query_formats, |
| .priv_size = sizeof(ExtraStereoContext), |
| .priv_class = &extrastereo_class, |
| .inputs = inputs, |
| .outputs = outputs, |
| }; |