mirror of https://github.com/FFmpeg/FFmpeg.git
Signed-off-by: Nicholas Robbins <nickrobbins@yahoo.com> Signed-off-by: Michael Niedermayer <michaelni@gmx.at>pull/58/head
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/*
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* Copyright (c) 2014 Nicholas Robbins |
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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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/**
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* @file |
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* remove judder in video stream |
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* |
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* Algorithm: |
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* - If the old packets had PTS of old_pts[i]. Replace these with new |
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* value based on the running average of the last n=cycle frames. So |
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* |
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* new_pts[i] = Sum(k=i-n+1, i, old_pts[k])/n |
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* + (old_pts[i]-old_pts[i-n])*(n-1)/2n |
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* |
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* For any repeating pattern of length n of judder this will produce |
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* an even progression of PTS's. |
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* |
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* - In order to avoid calculating this sum ever frame, a running tally |
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* is maintained in ctx->new_pts. Each frame the new term at the start |
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* of the sum is added, the one and the end is removed, and the offset |
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* terms (second line in formula above) are recalculated. |
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* |
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* - To aid in this a ringbuffer of the last n-2 PTS's is maintained in |
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* ctx->ringbuff. With the indices of the first two and last two entries |
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* stored in i1, i2, i3, & i4. |
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* |
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* - To ensure that the new PTS's are integers, time_base is divided |
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* by 2n. This removes the division in the new_pts calculation. |
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* |
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* - frame_rate is also multiplied by 2n to allow the frames to fall |
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* where they may in what may now be a VFR output. This produces more |
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* even output then setting frame_rate=1/0 in practice. |
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*/ |
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#include "libavutil/opt.h" |
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#include "libavutil/mathematics.h" |
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#include "avfilter.h" |
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#include "internal.h" |
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#include "video.h" |
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typedef struct { |
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const AVClass *class; |
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int64_t *ringbuff; |
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int i1, i2, i3, i4; |
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int64_t new_pts; |
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int start_count; |
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/* options */ |
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int cycle; |
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} DejudderContext; |
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#define OFFSET(x) offsetof(DejudderContext, x) |
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#define FLAGS AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM |
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static const AVOption dejudder_options[] = { |
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{"cycle", "set the length of the cycle to use for dejuddering", |
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OFFSET(cycle), AV_OPT_TYPE_INT, {.i64 = 4}, 2, 240, .flags = FLAGS}, |
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{NULL} |
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}; |
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AVFILTER_DEFINE_CLASS(dejudder); |
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static int config_out_props(AVFilterLink *outlink) |
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{ |
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AVFilterContext *ctx = outlink->src; |
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DejudderContext *dj = ctx->priv; |
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AVFilterLink *inlink = outlink->src->inputs[0]; |
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outlink->time_base = av_mul_q(inlink->time_base, av_make_q(1, 2 * dj->cycle)); |
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outlink->frame_rate = av_mul_q(inlink->frame_rate, av_make_q(2 * dj->cycle, 1)); |
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av_log(ctx, AV_LOG_VERBOSE, "cycle:%d\n", dj->cycle); |
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return 0; |
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} |
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static av_cold int dejudder_init(AVFilterContext *ctx) |
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{ |
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DejudderContext *dj = ctx->priv; |
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dj->ringbuff = av_mallocz(sizeof(*dj->ringbuff) * (dj->cycle+2)); |
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if (!dj->ringbuff) |
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return AVERROR(ENOMEM); |
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dj->new_pts = 0; |
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dj->i1 = 0; |
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dj->i2 = 1; |
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dj->i3 = 2; |
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dj->i4 = 3; |
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dj->start_count = dj->cycle + 2; |
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return 0; |
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} |
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static av_cold void dejudder_uninit(AVFilterContext *ctx) |
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{ |
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DejudderContext *dj = ctx->priv; |
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av_freep(&(dj->ringbuff)); |
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} |
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static int filter_frame(AVFilterLink *inlink, AVFrame *frame) |
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{ |
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int k; |
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AVFilterContext *ctx = inlink->dst; |
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AVFilterLink *outlink = ctx->outputs[0]; |
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DejudderContext *dj = ctx->priv; |
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int64_t *judbuff = dj->ringbuff; |
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int64_t next_pts = frame->pts; |
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int64_t offset; |
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if (next_pts == AV_NOPTS_VALUE) |
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return ff_filter_frame(outlink, frame); |
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if (dj->start_count) { |
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dj->start_count--; |
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dj->new_pts = next_pts * 2 * dj->cycle; |
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} else { |
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if (next_pts < judbuff[dj->i2]) { |
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offset = next_pts + judbuff[dj->i3] - judbuff[dj->i4] - judbuff[dj->i1]; |
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for (k = 0; k < dj->cycle + 2; k++) |
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judbuff[k] += offset; |
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} |
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dj->new_pts += (dj->cycle - 1) * (judbuff[dj->i3] - judbuff[dj->i1]) |
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+ (dj->cycle + 1) * (next_pts - judbuff[dj->i4]); |
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} |
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judbuff[dj->i2] = next_pts; |
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dj->i1 = dj->i2; |
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dj->i2 = dj->i3; |
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dj->i3 = dj->i4; |
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dj->i4 = (dj->i4 + 1) % (dj->cycle + 2); |
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frame->pts = dj->new_pts; |
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for (k = 0; k < dj->cycle + 2; k++) |
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av_log(ctx, AV_LOG_DEBUG, "%"PRId64"\t", judbuff[k]); |
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av_log(ctx, AV_LOG_DEBUG, "next=%"PRId64", new=%"PRId64"\n", next_pts, frame->pts); |
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return ff_filter_frame(outlink, frame); |
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} |
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static const AVFilterPad dejudder_inputs[] = { |
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{ |
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.name = "default", |
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.type = AVMEDIA_TYPE_VIDEO, |
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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 dejudder_outputs[] = { |
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{ |
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.name = "default", |
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.type = AVMEDIA_TYPE_VIDEO, |
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.config_props = config_out_props, |
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}, |
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{ NULL } |
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}; |
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AVFilter ff_vf_dejudder = { |
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.name = "dejudder", |
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.description = NULL_IF_CONFIG_SMALL("Remove judder produced by pullup."), |
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.priv_size = sizeof(DejudderContext), |
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.priv_class = &dejudder_class, |
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.inputs = dejudder_inputs, |
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.outputs = dejudder_outputs, |
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.init = dejudder_init, |
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.uninit = dejudder_uninit, |
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}; |
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