Aegisub/devel/OverLua/vfr.cpp

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/*
* VFR translation functions for OverLua
*
Copyright 2007 Niels Martin Hansen
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Contact:
E-mail: <jiifurusu@gmail.com>
IRC: jfs in #aegisub on irc.rizon.net
*/
#include "vfr.h"
#include <stdio.h>
#include <string.h>
#include <vector>
// Work with seconds per frame (spf) here instead of fps since that's more natural for the translation we're doing
class TimecodesV1 : public VFRTranslator {
private:
// Used when sections run out
double default_spf;
double first_non_section_timestamp;
int first_non_section_frame;
// Also generate sections for unspecified ones
// (use the default framerate then)
struct FrameRateSection {
double start_time;
double spf;
int start_frame;
int end_frame;
};
std::vector<FrameRateSection> sections;
public:
virtual double TimeStampFromFrameNumber(int n)
{
// Find correct section
for (size_t i = 0; i < sections.size(); i++) {
FrameRateSection &sect = sections[i];
if (n >= sect.start_frame && n <= sect.end_frame) {
return sect.start_time + (n - sect.start_frame) * sect.spf;
}
}
// Not in a section
if (n < 0) return 0.0;
return first_non_section_timestamp + (n - first_non_section_frame) * default_spf;
}
TimecodesV1(FILE *vfrfile)
{
char buf[100];
default_spf = -1;
double cur_time = 0.0;
FrameRateSection temp_section;
temp_section.start_time = 0.0;
temp_section.spf = -1;
temp_section.start_frame = 0;
temp_section.end_frame = 0;
while (fgets(buf, 100, vfrfile)) {
// Comment?
if (buf[0] == '#') continue;
if (strncmp(buf, "Assume ", 7) == 0 && default_spf < 0) {
char *num = buf+7;
default_spf = atof(num);
if (default_spf > 0)
default_spf = 1 / default_spf;
else
default_spf = -1;
temp_section.spf = default_spf;
continue;
}
int start_frame, end_frame;
double fps;
if (scanf("%d,%d,%f", &start_frame, &end_frame, &fps) == 3) {
// Finish the current temp section
temp_section.end_frame = start_frame - 1;
if (temp_section.end_frame >= temp_section.start_frame) {
cur_time += (temp_section.end_frame - temp_section.start_frame + 1) * temp_section.spf;
sections.push_back(temp_section);
}
// Insert the section corresponding to this line
temp_section.spf = 1/fps;
temp_section.start_frame = start_frame;
temp_section.end_frame = end_frame;
temp_section.start_time = cur_time;
cur_time += (end_frame - start_frame + 1) / fps;
sections.push_back(temp_section);
// Begin new temp section
temp_section.spf = default_spf;
temp_section.start_frame = end_frame + 1;
temp_section.end_frame = end_frame; // yes, negative duration
temp_section.start_time = cur_time;
}
}
first_non_section_timestamp = cur_time;
first_non_section_frame = temp_section.start_frame;
}
};
class TimecodesV2 : public VFRTranslator {
private:
// Main data
std::vector<double> timestamps;
// For when data are exhausted (well, they shouldn't, then the vfr file is bad)
int last_known_frame;
double last_known_timestamp;
double assumed_spf;
public:
virtual double TimeStampFromFrameNumber(int n)
{
if (n < (int)timestamps.size() && n >= 0) {
return timestamps[n];
}
if (n < 0) return 0.0;
return last_known_timestamp + (n - last_known_frame) * assumed_spf;
}
TimecodesV2(FILE *vfrfile)
{
char buf[50];
timestamps.reserve(8192); // should be enough for most cases
while (fgets(buf, 50, vfrfile)) {
// Comment?
if (buf[0] == '#') continue;
// Otherwise assume it's a good timestamp
timestamps.push_back(atof(buf));
}
last_known_frame = (int)timestamps.size()-1;
last_known_timestamp = timestamps[last_known_frame];
assumed_spf = 1/25.0; // yes, this is stupid - anyone got a better idea?
}
};
VFRTranslator *GetVFRTranslator(const char *vfrfile)
{
char buf[32];
buf[19] = 0; // In "# timecode format v1" the version number is character index 19
FILE *f = fopen(vfrfile, "r");
VFRTranslator *res = 0;
if (fgets(buf, 32, f) && buf[0] == '#') {
// So do some really shoddy parsing here, assume the file is good
if (buf[19] == '1') {
res = new TimecodesV1(f);
} else if (buf[19] == '2') {
res = new TimecodesV2(f);
}
}
fclose(f);
return res;
}