LUMIERA.clone/src/lib/time/timecode.cpp
Ichthyostega 38837da65e Timehandling: choose safer representation for fractional seconds (closes #939)
When drafting the time handling framework some years ago,
I foresaw the possible danger of mixing up numbers relating
to fractional seconds, with other plain numbers intended as
frame counts or as micro ticks. Thus I deliberately picked
an incompatible integer type for FSecs = boost::rational<long>

However, using long is problematic in itself, since its actual
bit length is not fixed, and especially on 32bit platforms long
is quite surprisingly defined to be the same as int.

However, meanwhile, using the new C++ features, I have blocked
pretty much any possible implicit conversion path, requiring
explicit conversions in the relevant ctor invocations. So,
after weighting in the alternatives, FSecs is now defined
as boost::rational<int64_t>.
2020-02-17 03:13:36 +01:00

488 lines
14 KiB
C++

/*
Timecode - implementation of fixed grid aligned time specifications
Copyright (C) Lumiera.org
2010, Hermann Vosseler <Ichthyostega@web.de>
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., 675 Mass Ave, Cambridge, MA 02139, USA.
* *****************************************************/
/** @file timecode.cpp
** Implementation parts of the timecode handling library.
** @todo a started implementation exists since 2010,
** yet crucial parts still need to be filled in as of 2016
*/
#include "lib/time/timecode.hpp"
#include "lib/time/timevalue.hpp"
#include "lib/time/timequant.hpp"
#include "lib/time/formats.hpp"
#include "lib/time.h"
#include "lib/util.hpp"
#include "lib/util-quant.hpp"
#include <regex>
#include <functional>
#include <boost/lexical_cast.hpp>
using util::unConst;
using util::isSameObject;
using util::floorwrap;
using std::string;
using std::regex;
using std::smatch;
using std::regex_search;
using boost::lexical_cast;
namespace error = lumiera::error;
namespace lib {
namespace time {
namespace format { /* ================= Timecode implementation details ======== */
LUMIERA_ERROR_DEFINE (INVALID_TIMECODE, "timecode format error, illegal value encountered");
/** try to parse a frame number specification
* @param frameNumber string containing an integral number with trailing '#'
* @param frameGrid coordinate system (and thus framerate) to use for the conversion
* @return (opaque internal) lumiera time value of the given frame's start position
* @throw error::Invalid in case of parsing failure
* @note the string may contain any additional content, as long as a
* regular-expression search is able to pick out a suitable value
*/
TimeValue
Frames::parse (string const& frameNumber, QuantR frameGrid)
{
static regex frameNr_parser{"(?:^|[^\\d\\.\\-])(\\-?\\d+)#"}; // no leading [.-\d], digit+'#'
smatch match; // note: ECMA regexp does not support lookbehind
if (regex_search (frameNumber, match, frameNr_parser))
return frameGrid.timeOf (lexical_cast<FrameCnt> (match[1]));
else
throw error::Invalid ("unable to parse framecount \""+frameNumber+"\""
, LERR_(INVALID_TIMECODE));
}
TimeValue
Smpte::parse (string const&, QuantR)
{
UNIMPLEMENTED("parsing SMPTE timecode");
}
TimeValue
Hms::parse (string const&, QuantR)
{
UNIMPLEMENTED("parse a hours:mins:secs time specification");
}
/** try to parse a time specification in seconds or fractional seconds.
* The value is interpreted relative to the origin of a the given time grid
* This parser recognises full seconds, fractional seconds and both together.
* In any case, the actual number is required to end with a trailing \c 'sec'
* @par Example specifications
\verbatim
12sec --> 12 * TimeValue::SCALE
-4sec --> -4 * TimeValue::SCALE
5/4sec --> 1.25 * TimeValue::SCALE
-5/25sec --> -0.2 * TimeValue::SCALE
1+1/2sec --> 1.5 * TimeValue::SCALE
1-1/25sec --> 0.96 * TimeValue::SCALE
-12-1/4sec --> -11.75 * TimeValue::SCALE
\endverbatim
* @param seconds string containing a time spec in seconds
* @param grid coordinate system the parsed value is based on
* @return the corresponding (opaque internal) lumiera time value
* @throw error::Invalid in case of parsing failure
* @note the string may contain any additional content, as long as a
* regular-expression search is able to pick out a suitable value
*/
TimeValue
Seconds::parse (string const& seconds, QuantR grid)
{
static regex fracSecs_parser ("(?:^|[^\\./\\d\\-])(\\-?\\d+)(?:([\\-\\+]\\d+)?/(\\d+))?sec");
//__no leading[./-\d] number [+-] number '/' number 'sec'
#define SUB_EXPR(N) lexical_cast<int> (match[N])
smatch match;
if (regex_search (seconds, match, fracSecs_parser))
if (match[2].matched)
{
// complete spec with all parts
FSecs fractionalPart (SUB_EXPR(2), SUB_EXPR(3));
int fullSeconds (SUB_EXPR(1));
return grid.timeOf (fullSeconds + fractionalPart);
}
else
if (match[3].matched)
{
// only a fractional part was given
return grid.timeOf (FSecs (SUB_EXPR(1), SUB_EXPR(3)));
}
else
{
// just simple non-fractional seconds
return grid.timeOf (FSecs (SUB_EXPR(1)));
}
else
throw error::Invalid ("unable to parse \""+seconds+"\" as (fractional)seconds"
, LERR_(INVALID_TIMECODE));
}
/** build up a frame count
* by quantising the given time value
*/
void
Frames::rebuild (FrameNr& framecnt, QuantR quantiser, TimeValue const& rawTime)
{
framecnt.setValueRaw (quantiser.gridPoint (rawTime));
}
/** calculate the time point denoted by this frame count */
TimeValue
Frames::evaluate (FrameNr const& framecnt, QuantR quantiser)
{
return quantiser.timeOf (framecnt);
}
/** build up a SMPTE timecode
* by quantising the given time value and then splitting it
* into hours, minutes, seconds and frame offset.
*/
void
Smpte::rebuild (SmpteTC& tc, QuantR quantiser, TimeValue const& rawTime)
{
tc.clear();
tc.frames = quantiser.gridPoint (rawTime);
// will automatically wrap over to the seconds, minutes and hour fields
}
/** calculate the time point denoted by this SMPTE timecode,
* by summing up the timecode's components */
TimeValue
Smpte::evaluate (SmpteTC const& tc, QuantR quantiser)
{
uint frameRate = tc.getFps();
int64_t gridPoint(tc.frames);
gridPoint += int64_t(tc.secs) * frameRate;
gridPoint += int64_t(tc.mins) * frameRate * 60;
gridPoint += int64_t(tc.hours) * frameRate * 60 * 60;
return quantiser.timeOf (tc.sgn * gridPoint);
}
/** yield the Framerate in effect at that point.
* Especially Timecode in SMPTE format exposes a "frames" field
* to contain the remainder of frames in addition to the h:m:s value.
* Obviously this value has to be kept below the number of frames for
* a full second and wrap around accordingly.
* @note SMPTE format assumes this framerate to be constant. Actually,
* in this implementation the value returned here neither needs
* to be constant (independent of the given rawTime), nor does
* it need to be the actual framerate used by the quantiser.
* Especially in case of NTSC drop-frame, the timecode
* uses 30fps here, while the quantisation uses 29.97
* @todo this design just doesn't feel quite right...
*/
uint
Smpte::getFramerate (QuantR quantiser_, TimeValue const& rawTime)
{
FrameCnt refCnt = quantiser_.gridPoint(rawTime);
FrameCnt newCnt = quantiser_.gridPoint(Time(0,1) + rawTime);
FrameCnt effectiveFrames = newCnt - refCnt;
ENSURE (1000 > effectiveFrames);
ENSURE (0 < effectiveFrames);
return uint(effectiveFrames);
}
/** handle the limits of SMPTE timecode range.
* This is an extension and configuration point to control how
* to handle values beyond the official SMPTE timecode range of
* 0:0:0:0 to 23:59:59:##. When this strategy function is invoked,
* the frames, seconds, minutes and hours fields have already been processed
* and stored into the component digxels, under the assumption the overall
* value stays in range.
* @note currently the range is extended "naturally" (i.e. mathematically).
* The representation is flipped around the zero point and the value
* of the hours is just allowed to increase beyond 23
* @todo If necessary, this extension point should be converted into a
* configurable strategy. Possible variations
* - clip values beyond the boundaries
* - throw an exception on illegal values
* - wrap around from 23:59:59:## to 0:0:0:0
* - just make the hour negative, but continue with the same
* orientation (0:0:0:0 - 1sec = -1:59:59:0)
*/
void
Smpte::applyRangeLimitStrategy (SmpteTC& tc)
{
if (tc.hours < 0)
tc.invertOrientation();
}
}
namespace { // Timecode implementation details
typedef util::IDiv<int> Div;
void
wrapFrames (SmpteTC* thisTC, int rawFrames)
{
Div scaleRelation = floorwrap<int> (rawFrames, thisTC->getFps());
thisTC->frames.setValueRaw (scaleRelation.rem);
thisTC->secs += scaleRelation.quot;
}
void
wrapSeconds (SmpteTC* thisTC, int rawSecs)
{
Div scaleRelation = floorwrap (rawSecs, 60);
thisTC->secs.setValueRaw (scaleRelation.rem);
thisTC->mins += scaleRelation.quot;
}
void
wrapMinutes (SmpteTC* thisTC, int rawMins)
{
Div scaleRelation = floorwrap (rawMins, 60);
thisTC->mins.setValueRaw (scaleRelation.rem);
thisTC->hours += scaleRelation.quot;
}
void
wrapHours (SmpteTC* thisTC, int rawHours)
{
thisTC->hours.setValueRaw (rawHours);
format::Smpte::applyRangeLimitStrategy (*thisTC);
}
using std::bind;
using std::placeholders::_1;
/** bind the individual Digxel mutation functors
* to normalise raw component values */
inline void
setupComponentNormalisation (SmpteTC& thisTC)
{
thisTC.hours.installMutator (wrapHours, thisTC);
thisTC.mins.installMutator (wrapMinutes, thisTC);
thisTC.secs.installMutator (wrapSeconds, thisTC);
thisTC.frames.installMutator(wrapFrames, thisTC);
}
}//(End)implementation details
/** */
FrameNr::FrameNr (QuTime const& quantisedTime)
: TCode(quantisedTime)
, CountVal()
{
quantisedTime.castInto (*this);
}
/** */
SmpteTC::SmpteTC (QuTime const& quantisedTime)
: TCode(quantisedTime)
, effectiveFramerate_(Format::getFramerate (*quantiser_, quantisedTime))
{
setupComponentNormalisation (*this);
quantisedTime.castInto (*this);
}
SmpteTC::SmpteTC (SmpteTC const& o)
: TCode(o)
, effectiveFramerate_(o.effectiveFramerate_)
{
setupComponentNormalisation (*this);
sgn = o.sgn;
hours = o.hours;
mins = o.mins;
secs = o.secs;
frames = o.frames;
}
SmpteTC&
SmpteTC::operator= (SmpteTC const& o)
{
if (!isSameObject (*this, o))
{
TCode::operator= (o);
effectiveFramerate_ = o.effectiveFramerate_;
sgn = o.sgn;
hours = o.hours;
mins = o.mins;
secs = o.secs;
frames = o.frames;
}
return *this;
}
/** */
HmsTC::HmsTC (QuTime const& quantisedTime)
: TCode(quantisedTime)
// : tpoint_(quantisedTime) /////////////////////////////TODO bullshit
{ }
/** */
Secs::Secs (QuTime const& quantisedTime)
: TCode(quantisedTime)
// : sec_(TimeVar(quantisedTime) / GAVL_TIME_SCALE) /////////////TODO bullshit
{ }
void
SmpteTC::clear()
{
frames.setValueRaw(0);
secs.setValueRaw (0);
mins.setValueRaw (0);
hours.setValueRaw (0);
sgn.setValueRaw (+1);
}
void
SmpteTC::rebuild()
{
TimeValue point = Format::evaluate (*this, *quantiser_);
Format::rebuild (*this, *quantiser_, point);
}
/** flip the orientation of min, sec, and frames.
* Besides changing the sign, this will flip the
* meaning of the component fields, which by
* definition are always oriented towards zero.
*
* Normalised value fields are defined positive,
* with automatic overflow to next higher field.
* This might cause the hours to become negative.
* When invoked in this case, the meaning changes
* from -h + (m+s+f) to -(h+m+s+f)
*/
void
SmpteTC::invertOrientation()
{
int fr (getFps());
int f (fr - frames); // revert orientation
int s (60 - secs); // of the components
int m (60 - mins); //
int h = -hours; // assumed to be negative
sgn *= -1; // flip sign field
if (f < fr) --s; else f -= fr;
if (s < 60) --m; else s -= 60;
if (m < 60) --h; else m -= 60;
hours.setValueRaw(h);
mins = m; // invoking setters
secs = s; // ensures normalisation
frames = f;
}
uint
SmpteTC::getFps() const
{
return effectiveFramerate_; //////////////////////////////////TODO better design. Shouldn't Format::getFramerate(QuantR, TimeValue) be moved here?
}
string
SmpteTC::show() const
{
string tc;
tc.reserve(15);
tc += sgn.show();
tc += hours.show();
tc += ':';
tc += mins.show();
tc += ':';
tc += secs.show();
tc += ':';
tc += frames.show();
return tc;
}
SmpteTC&
SmpteTC::operator++ ()
{
frames += sgn;
return *this;
}
SmpteTC&
SmpteTC::operator-- ()
{
frames -= sgn;
return *this;
}
/** */
int
HmsTC::getSecs() const
{
return lumiera_time_seconds (tpoint_);
}
/** */
int
HmsTC::getMins() const
{
return lumiera_time_minutes (tpoint_);
}
/** */
int
HmsTC::getHours() const
{
return lumiera_time_hours (tpoint_);
}
/** */
double
HmsTC::getMillis() const
{
TODO ("Frame-Quantisation");
return lumiera_time_millis (tpoint_);
}
/** */
}} // lib::time