/* * Copyright (c) 2000 Chris Ausbrooks <weed@bucket.pp.ualr.edu> * Copyright (c) 2000 Fabien COELHO <fabien@coelho.net> * * 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/opt.h" #include "libavutil/samplefmt.h" #include "avfilter.h" #include "audio.h" #include "internal.h" typedef struct DCShiftContext { const AVClass *class; double dcshift; double limiterthreshold; double limitergain; } DCShiftContext; #define OFFSET(x) offsetof(DCShiftContext, x) #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM static const AVOption dcshift_options[] = { { "shift", "set DC shift", OFFSET(dcshift), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -1, 1, A }, { "limitergain", "set limiter gain", OFFSET(limitergain), AV_OPT_TYPE_DOUBLE, {.dbl=0}, 0, 1, A }, { NULL } }; AVFILTER_DEFINE_CLASS(dcshift); static av_cold int init(AVFilterContext *ctx) { DCShiftContext *s = ctx->priv; s->limiterthreshold = INT32_MAX * (1.0 - (fabs(s->dcshift) - s->limitergain)); return 0; } static int query_formats(AVFilterContext *ctx) { AVFilterChannelLayouts *layouts; AVFilterFormats *formats; static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_S32P, AV_SAMPLE_FMT_NONE }; int ret; layouts = ff_all_channel_counts(); if (!layouts) return AVERROR(ENOMEM); ret = ff_set_common_channel_layouts(ctx, layouts); if (ret < 0) return ret; formats = ff_make_format_list(sample_fmts); if (!formats) return AVERROR(ENOMEM); ret = ff_set_common_formats(ctx, formats); if (ret < 0) return ret; formats = ff_all_samplerates(); if (!formats) return AVERROR(ENOMEM); return ff_set_common_samplerates(ctx, formats); } static int filter_frame(AVFilterLink *inlink, AVFrame *in) { AVFilterContext *ctx = inlink->dst; AVFilterLink *outlink = ctx->outputs[0]; AVFrame *out; DCShiftContext *s = ctx->priv; int i, j; double dcshift = s->dcshift; if (av_frame_is_writable(in)) { out = in; } else { out = ff_get_audio_buffer(outlink, in->nb_samples); if (!out) { av_frame_free(&in); return AVERROR(ENOMEM); } av_frame_copy_props(out, in); } if (s->limitergain > 0) { for (i = 0; i < inlink->channels; i++) { const int32_t *src = (int32_t *)in->extended_data[i]; int32_t *dst = (int32_t *)out->extended_data[i]; for (j = 0; j < in->nb_samples; j++) { double d; d = src[j]; if (d > s->limiterthreshold && dcshift > 0) { d = (d - s->limiterthreshold) * s->limitergain / (INT32_MAX - s->limiterthreshold) + s->limiterthreshold + dcshift; } else if (d < -s->limiterthreshold && dcshift < 0) { d = (d + s->limiterthreshold) * s->limitergain / (INT32_MAX - s->limiterthreshold) - s->limiterthreshold + dcshift; } else { d = dcshift * INT32_MAX + d; } dst[j] = av_clipl_int32(d); } } } else { for (i = 0; i < inlink->channels; i++) { const int32_t *src = (int32_t *)in->extended_data[i]; int32_t *dst = (int32_t *)out->extended_data[i]; for (j = 0; j < in->nb_samples; j++) { double d = dcshift * (INT32_MAX + 1.) + src[j]; dst[j] = av_clipl_int32(d); } } } if (out != in) av_frame_free(&in); return ff_filter_frame(outlink, out); } static const AVFilterPad dcshift_inputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, .filter_frame = filter_frame, }, { NULL } }; static const AVFilterPad dcshift_outputs[] = { { .name = "default", .type = AVMEDIA_TYPE_AUDIO, }, { NULL } }; AVFilter ff_af_dcshift = { .name = "dcshift", .description = NULL_IF_CONFIG_SMALL("Apply a DC shift to the audio."), .query_formats = query_formats, .priv_size = sizeof(DCShiftContext), .priv_class = &dcshift_class, .init = init, .inputs = dcshift_inputs, .outputs = dcshift_outputs, .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, };