Mac Dev Center Mac OS X Reference Library Drivers, Kernel, & Hardware: User-Space Device Access Disc Recording Framework Reference

Overview

Representation of a time interval expressed in minutes, seconds and frames.

Discussion

On CDs, minutes/seconds/frames are used to identify positioning on a disc (which is most useful on an audio disc), but applies to any position on a disc no matter what type of data is present.

A frame is equivalent to a sector or block in normal disk parlance. 75 frames make up one second, so a 2 second pause (typical pregap size) is 150 frames.

Methods

-description

Returns a textual representation of the receiver.

-descriptionWithFormat:

Returns a textual representation of the receiver.

-frames

Returns the number of frames represented by the receiver.

-initWithFrames:

Initializes an msf object whose length is frames.

-initWithString:

Initializes an msf object initialized to the value represented by string

-isEqualToMSF:

Compares on emsf to another.

-minutes

Returns the number of minutes represented by the receiver.

+msf

Creates an msf object with no length/time.

-msfByAdding:

Adds an msf to the receiver.

-msfBySubtracting:

Subtracts an msf to the receiver.

+msfWithFrames:

Creates an msf object whose length is frames.

+msfWithString:

Creates an msf object initialized to the value represented by string

-seconds

Returns the number of seconds represented by the receiver.

-sectors

Returns the total number of frames/sectors represented by the receiver.

Returns a textual representation of the receiver.

- (NSString*) description; 

Return Value

NSString containing a textual representation of the object with the standard formatting.

Returns a textual representation of the receiver.

- (NSString*) descriptionWithFormat:(NSString*) format; 

Parameters

Return Value

NSString containing a textual representation of the object utilizing the specified format.

Discussion

The format string is very similar to a printf-style format string with %-escaped formatting characters.

• %% A "%" character
• %m Minutes as a decimal number
• %s Seconds as a decimal number
• %f Frames as a decimal number

In addition to these formatting characters an optional length specifier can come between then % and the formatting character. This length specifier will force the field in question to be at least that wide. For example a format specifier of "%02m:%02s" will cause a DRMSF object representing 3 minutes 9 seconds to be formatted as "03:09".

A formatter is aware of and respects rounding. If a bit of the msf is not zero, but the format does not display that value, the next higher value will be increased by one to reflect that. Extending our example above, an DRMSF with a value of 3 minutes, 9 seconds, 15 frames using a format specfier of "%02m:%02s", will be formatted as "03:10" since the 15 frames rounds up the seconds to the next value

Returns the number of frames represented by the receiver.

- (UInt32) frames; 

Discussion

This method differs from sectors in that it returns to the caller the number of frames remaining in the current second. For example an DRMSF value of 5:30:72 will return 72 from a message to frames.

Initializes an msf object whose length is frames.

- (id) initWithFrames:(UInt32)frames; 

Return Value

A DRMSF object.

Initializes an msf object initialized to the value represented by string

- (id) initWithString:(NSString*)string; 

Return Value

A DRMSF object.

Compares on emsf to another.

- (BOOL) isEqualToMSF:(DRMSF*)otherDRMSF; 

Parameters

Return Value

YES if the two object are equal, NO otherwise.

Returns the number of minutes represented by the receiver.

- (UInt32) minutes; 

Discussion

If the receiver represents a non integral number of minutes, only the whole minute value is returned. For example an DRMSF value of 5:30:72 will return 5 from a message to minutes.

Creates an msf object with no length/time.

+ (DRMSF*) msf; 

Return Value

An autoreleased DRMSF object.

Adds an msf to the receiver.

- (DRMSF*) msfByAdding:(DRMSF*)msf; 

Parameters

Return Value

A new DRMSF object totalling the sum of the reciever and msf

Subtracts an msf to the receiver.

- (DRMSF*) msfBySubtracting:(DRMSF*)msf; 

Parameters

Return Value

A new DRMSF object totalling the difference of the reciever and msf

Creates an msf object whose length is frames.

+ (DRMSF*) msfWithFrames:(UInt32)frames; 

Return Value

An autoreleased DRMSF object.

Creates an msf object initialized to the value represented by string

+ (DRMSF*) msfWithString:(NSString*)string; 

Return Value

An autoreleased DRMSF object.

Returns the number of seconds represented by the receiver.

- (UInt32) seconds; 

Discussion

If the receiver represents a non integral number of seconds, only the whole second value is returned. For example an DRMSF value of 5:30:72 will return 30 from a message to seconds.

Returns the total number of frames/sectors represented by the receiver.

- (UInt32) sectors; 

Discussion

This method differs from frames in that it returns to the caller the total number of frames/sectors represented by the object. For example an DRMSF value of 5:30:72 will return 24822 from a message to sectors.