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/* |
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* Copyright (c) 2015 The FFmpeg Project |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/channel_layout.h" |
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#include "libavutil/opt.h" |
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#include "avfilter.h" |
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#include "audio.h" |
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#include "formats.h" |
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typedef struct ExtraStereoContext { |
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const AVClass *class; |
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float mult; |
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int clip; |
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} ExtraStereoContext; |
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#define OFFSET(x) offsetof(ExtraStereoContext, x) |
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#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM |
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static const AVOption extrastereo_options[] = { |
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{ "m", "set the difference coefficient", OFFSET(mult), AV_OPT_TYPE_FLOAT, {.dbl=2.5}, -10, 10, A }, |
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{ "c", "enable clipping", OFFSET(clip), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, A }, |
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{ NULL } |
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}; |
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AVFILTER_DEFINE_CLASS(extrastereo); |
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static int query_formats(AVFilterContext *ctx) |
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{ |
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AVFilterFormats *formats = NULL; |
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AVFilterChannelLayouts *layout = NULL; |
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int ret; |
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✓✗✓✗
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if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_FLT )) < 0 || |
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✓✗ |
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(ret = ff_set_common_formats (ctx , formats )) < 0 || |
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✗✓ |
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(ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 || |
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(ret = ff_set_common_channel_layouts (ctx , layout )) < 0) |
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return ret; |
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formats = ff_all_samplerates(); |
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return ff_set_common_samplerates(ctx, formats); |
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} |
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static int filter_frame(AVFilterLink *inlink, AVFrame *in) |
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{ |
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AVFilterContext *ctx = inlink->dst; |
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AVFilterLink *outlink = ctx->outputs[0]; |
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ExtraStereoContext *s = ctx->priv; |
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const float *src = (const float *)in->data[0]; |
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const float mult = s->mult; |
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AVFrame *out; |
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float *dst; |
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int n; |
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✓✗ |
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if (av_frame_is_writable(in)) { |
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out = in; |
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} else { |
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out = ff_get_audio_buffer(outlink, in->nb_samples); |
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if (!out) { |
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av_frame_free(&in); |
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return AVERROR(ENOMEM); |
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} |
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av_frame_copy_props(out, in); |
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} |
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dst = (float *)out->data[0]; |
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✓✓ |
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for (n = 0; n < in->nb_samples; n++) { |
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float average, left, right; |
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left = src[n * 2 ]; |
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right = src[n * 2 + 1]; |
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average = (left + right) / 2.; |
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left = average + mult * (left - average); |
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right = average + mult * (right - average); |
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✓✗ |
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if (s->clip) { |
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left = av_clipf(left, -1, 1); |
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right = av_clipf(right, -1, 1); |
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} |
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dst[n * 2 ] = left; |
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dst[n * 2 + 1] = right; |
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} |
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✗✓ |
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if (out != in) |
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av_frame_free(&in); |
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return ff_filter_frame(outlink, out); |
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} |
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static const AVFilterPad inputs[] = { |
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{ |
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.name = "default", |
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.type = AVMEDIA_TYPE_AUDIO, |
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.filter_frame = filter_frame, |
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}, |
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{ NULL } |
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}; |
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static const AVFilterPad outputs[] = { |
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{ |
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.name = "default", |
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.type = AVMEDIA_TYPE_AUDIO, |
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}, |
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{ NULL } |
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}; |
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AVFilter ff_af_extrastereo = { |
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.name = "extrastereo", |
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.description = NULL_IF_CONFIG_SMALL("Increase difference between stereo audio channels."), |
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.query_formats = query_formats, |
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.priv_size = sizeof(ExtraStereoContext), |
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.priv_class = &extrastereo_class, |
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.inputs = inputs, |
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.outputs = outputs, |
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.flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, |
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.process_command = ff_filter_process_command, |
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}; |