SmpteTC Class Reference

#include "lib/time/timecode.hpp"

Description

Classical Timecode value reminiscent to SMPTE format.

After quantisation, the resulting (materialised) time value is decimated into a hours, a minutes, a seconds part and the remainder is cast into a frame number relative to the seconds. Consequently, a SmpteTC representation is always linked implicitly to a specific framerate.

range extensions

Historically, SMPTE timecode format was focused mainly on how to encode a unique timestamp in a way allowing to 'piggyback' these timestamps into an existing (analogue) media data format. As a side effect, quite tight limits had to be imposed on the possible component values in such a fixed-length format. This whole concern is completely beyond the scope of a typical computer based video implementation; thus we can consider ways to extend the value range to be represented in this SMPTE-like timecode format:

• we can allow time values below the zero point
• we can allow time values beyond 24 hours. Several different schemes how to do this extensions could be devised (and in addition, we could also wrap around the hours field, jumping from 23:59:59:## to 0:0:0:0). Currently, we implement an extension, where the timecode representation is symmetrical to the zero point and the hours field is just extended beyond 23 hours. To give an example: 0:0:0:0 minus 1 frame yields -0:0:0:1

Todo:

the range extension scheme could be a configurable strategy

Definition at line 150 of file timecode.hpp.

Public Types
typedef format::Smpte	Format

Public Member Functions
	SmpteTC (QuTime const &quantisedTime)
	SmpteTC (SmpteTC const &)
void	clear ()
uint	getFps () const
void	invertOrientation ()
	flip the orientation of min, sec, and frames. More...
SmpteTC &	operator++ ()
SmpteTC &	operator-- ()
SmpteTC &	operator= (SmpteTC const &)
void	rebuild ()
Public Member Functions inherited from TCode
string	describe () const
Time	getTime () const
	operator string () const

Public Attributes
SexaDigit	frames
HourDigit	hours
SexaDigit	mins
SexaDigit	secs
Signum	sgn

Private Member Functions
virtual string	show () const
virtual Literal	tcID () const
virtual TimeValue	value () const

Private Attributes
uint	effectiveFramerate_

Additional Inherited Members
Protected Member Functions inherited from TCode
	TCode (PQuant const &quant)
Protected Attributes inherited from TCode
PQuant	quantiser_

Member Function Documentation

invertOrientation()

void invertOrientation

(

)

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)

Definition at line 398 of file timecode.cpp.

Referenced by Smpte::applyRangeLimitStrategy().

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Inheritance diagram for SmpteTC:

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The documentation for this class was generated from the following files:

• timecode.hpp
• timecode.cpp