ffmpeg/libavfilter/vsrc_mandelbrot.c

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/*
* Copyright (c) 2011 Michael Niedermayer
*
* 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
*
* The vsrc_color filter from Stefano Sabatini was used as template to create
* this
*/
/**
* @file
* Mandelbrot fraktal renderer
*/
#include "avfilter.h"
#include "libavutil/imgutils.h"
#include "libavutil/parseutils.h"
enum Outer{
ITERATION_COUNT,
NORMALIZED_ITERATION_COUNT,
};
typedef struct {
int w, h;
AVRational time_base;
uint64_t pts;
int maxiter;
double start_x;
double start_y;
double start_scale;
double end_scale;
double end_pts;
double bailout;
enum Outer outer;
} MBContext;
static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
{
MBContext *mb = ctx->priv;
char frame_size [128] = "320x240";
char frame_rate [128] = "25";
AVRational frame_rate_q;
int ret;
mb->maxiter=256;
mb->start_x=0;
mb->start_y=1;
mb->start_scale=3.0;
mb->end_scale=0.3;
mb->end_pts=200;
mb->bailout=100;
mb->outer= NORMALIZED_ITERATION_COUNT;
if (args)
sscanf(args, "%127[^:]:%127[^:]:%d,%lf:%lf:%lf", frame_size, frame_rate, &mb->maxiter, &mb->start_x, &mb->start_y, &mb->start_scale);
if (av_parse_video_size(&mb->w, &mb->h, frame_size) < 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid frame size: %s\n", frame_size);
return AVERROR(EINVAL);
}
mb->start_scale /=mb->h;
mb->end_scale /=mb->h;
if (av_parse_video_rate(&frame_rate_q, frame_rate) < 0 ||
frame_rate_q.den <= 0 || frame_rate_q.num <= 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid frame rate: %s\n", frame_rate);
return AVERROR(EINVAL);
}
mb->time_base.num = frame_rate_q.den;
mb->time_base.den = frame_rate_q.num;
return 0;
}
static av_cold void uninit(AVFilterContext *ctx)
{
MBContext *mb = ctx->priv;
int i;
}
static int query_formats(AVFilterContext *ctx)
{
static const enum PixelFormat pix_fmts[] = {
PIX_FMT_BGR32,
PIX_FMT_NONE
};
avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
return 0;
}
static int config_props(AVFilterLink *inlink)
{
AVFilterContext *ctx = inlink->src;
MBContext *mb = ctx->priv;
if (av_image_check_size(mb->w, mb->h, 0, ctx) < 0)
return AVERROR(EINVAL);
inlink->w = mb->w;
inlink->h = mb->h;
inlink->time_base = mb->time_base;
return 0;
}
static void draw_mandelbrot(AVFilterContext *ctx, uint32_t *color, int linesize, int64_t pts)
{
MBContext *mb = ctx->priv;
int x,y,i;
double scale= mb->start_scale*pow(mb->end_scale/mb->start_scale, pts/mb->end_pts);
for(y=0; y<mb->h; y++){
for(x=0; x<mb->w; x++){
const double cr=mb->start_x+scale*(x-mb->w/2);
const double ci=mb->start_y+scale*(y-mb->h/2);
double zr=cr;
double zi=ci;
uint32_t c=0;
for(i=0; i<mb->maxiter; i++){
double t;
if(zr*zr + zi*zi > mb->bailout){
switch(mb->outer){
case ITERATION_COUNT: zr= i; break;
case NORMALIZED_ITERATION_COUNT: zr= i + (log(log(mb->bailout)) - log(log(sqrt(zr*zr + zi*zi))))/log(2); break;
}
c= lrintf((sin(zr)+1)*127) + lrintf((sin(zr/1.234)+1)*127)*256*256 + lrintf((sin(zr/100)+1)*127)*256;
break;
}
t= zr*zr - zi*zi;
zi= 2*zr*zi + ci;
zr= t + cr;
}
color[x + y*linesize]= c;
}
}
}
static int request_frame(AVFilterLink *link)
{
MBContext *mb = link->src->priv;
AVFilterBufferRef *picref = avfilter_get_video_buffer(link, AV_PERM_WRITE, mb->w, mb->h);
picref->video->sample_aspect_ratio = (AVRational) {1, 1};
picref->pts = mb->pts++;
picref->pos = -1;
avfilter_start_frame(link, avfilter_ref_buffer(picref, ~0));
draw_mandelbrot(link->src, picref->data[0], picref->linesize[0]/4, picref->pts);
avfilter_draw_slice(link, 0, mb->h, 1);
avfilter_end_frame(link);
avfilter_unref_buffer(picref);
return 0;
}
AVFilter avfilter_vsrc_mandelbrot = {
.name = "mandelbrot",
.description = NULL_IF_CONFIG_SMALL("Mandelbrot renderer"),
.priv_size = sizeof(MBContext),
.init = init,
.uninit = uninit,
.query_formats = query_formats,
.inputs = (const AVFilterPad[]) {{ .name = NULL}},
.outputs = (const AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.request_frame = request_frame,
.config_props = config_props },
{ .name = NULL}},
};