ts::TLVSyntax Class Reference

Representation of a Tag, Length, Value (TVL) syntax. More...

#include <tsTLVSyntax.h>

Public Member Functions
	TLVSyntax (int start=-1, int size=-1, size_t tagSize=1, size_t lengthSize=1, bool msb=true, Report &report=(ts::CerrReport::Instance()))
	Default constructor.
bool	fromString (const UString &s, Report &report=(ts::CerrReport::Instance()))
	Set the values of a TLVSyntax object from a string representation.
size_t	getLengthSize () const
	Get the size in bytes of the Length field.
size_t	getTagAndLength (const uint8_t *data, size_t size, uint32_t &tag, size_t &length) const
	Extract a tag and length value from a data area.
size_t	getTagSize () const
	Get the size in bytes of the Tag field.
bool	locateTLV (const uint8_t *data, size_t dataSize, size_t &tlvStart, size_t &tlvSize) const
	Locate the "TLV area" inside a data area.
bool	operator< (const TLVSyntax &other) const
	Comparison operator, typically used to sort containers of TLVSyntax.
bool	set (int start=-1, int size=-1, size_t tagSize=1, size_t lengthSize=1, bool msb=true, Report &report=(ts::CerrReport::Instance()))
	Set the values of a TLVSyntax object.
void	setAutoLocation ()
	Update the TLV syntax to automatically locate the TLV area.

Detailed Description

Representation of a Tag, Length, Value (TVL) syntax.

An instance of this class describe how a part of a data area, typically in the payload of an MPEG section, is structured as a suite of TLV records. The complete suite of all contiguous TLV records is named the "TLV area" inside the larger data area.

A TLV area is described by the following values:

• The start index in the data area. This is the starting index of the first tag field. A negative value for start means "auto". The best match of a "TLV area" will be found automatically.
• The size in bytes of the TLV area. A negative value means "auto", up to the last consistent TLV record before the end of the data area.
• The tag size in bytes. The valid sizes are 1 (default), 2 and 4.
• The length size in bytes. The valid sizes are 1 (default), 2 and 4.
• The byte order of the tag and length fields. The default is MSB.

Constructor & Destructor Documentation

TLVSyntax()

ts::TLVSyntax::TLVSyntax	(	int	start = -1,
		int	size = -1,
		size_t	tagSize = 1,
		size_t	lengthSize = 1,
		bool	msb = true,
		Report &	report = (ts::CerrReport::Instance())
	)

Default constructor.

Parameters

[in]	start	Starting index of the "TLV area" in the "data area". A negative value means "auto".
[in]	size	Size in bytes of the "TLV area". A negative value means "auto".
[in]	tagSize	Size in bytes of the tag field. The valid sizes are 1 (default), 2 and 4.
[in]	lengthSize	Size in bytes of the length field. The valid sizes are 1 (default), 2 and 4.
[in]	msb	If true, the tag and length fields are represented in MSB-first.
[in,out]	report	Where to report errors.

Member Function Documentation

set()

bool ts::TLVSyntax::set	(	int	start = -1,
		int	size = -1,
		size_t	tagSize = 1,
		size_t	lengthSize = 1,
		bool	msb = true,
		Report &	report = (ts::CerrReport::Instance())
	)

Set the values of a TLVSyntax object.

Parameters

[in]	start	Starting index of the "TLV area" in the "data area". A negative value means "auto".
[in]	size	Size in bytes of the "TLV area". A negative value means "auto".
[in]	tagSize	Size in bytes of the tag field. The valid sizes are 1 (default), 2 and 4.
[in]	lengthSize	Size in bytes of the length field. The valid sizes are 1 (default), 2 and 4.
[in]	msb	If true, the tag and length fields are represented in MSB-first.
[in,out]	report	Where to report errors.

Returns

True on success, false on error (invalid sizes).

getTagSize()

size_t ts::TLVSyntax::getTagSize ( ) const

inline

Get the size in bytes of the Tag field.

Returns

The size in bytes of the Tag field.

getLengthSize()

size_t ts::TLVSyntax::getLengthSize ( ) const

inline

Get the size in bytes of the Length field.

Returns

The size in bytes of the Length field.

fromString()

bool ts::TLVSyntax::fromString	(	const UString &	s,
		Report &	report = (ts::CerrReport::Instance())
	)

Set the values of a TLVSyntax object from a string representation.

Typically used to ingest command line parameters.

Parameters

[in]	s	The string representation in the form "start,size,tagSize,lengthSize,order". The start and size fields can be set to "auto". The order field shall be either "msb" or lsb". All fields are optional. Missing fields receive the default value as defined in the constructor.
[in,out]	report	Where to report errors.

Returns

True on success, false on error.

getTagAndLength()

size_t ts::TLVSyntax::getTagAndLength	(	const uint8_t *	data,
		size_t	size,
		uint32_t &	tag,
		size_t &	length
	)		const

Extract a tag and length value from a data area.

Parameters

[in]	data	Address of the TLV record.
[in]	size	Total size in bytes of the data area after data address.
[out]	tag	Returned tag value.
[out]	length	Returned length value.

Returns

The size of the tag and length field, ie. the offset after data where the value field starts. Return 0 on error (if the TLV record does not fit).

locateTLV()

bool ts::TLVSyntax::locateTLV	(	const uint8_t *	data,
		size_t	dataSize,
		size_t &	tlvStart,
		size_t &	tlvSize
	)		const

Locate the "TLV area" inside a data area.

If the start or size are set to "auto", return the best match.

Parameters

[in]	data	Address of the TLV data area.
[in]	dataSize	Total size in bytes of the data area.
[out]	tlvStart	Starting offset of the "TLV area" after data.
[out]	tlvSize	Size in bytes of the "TLV area". Zero if no suitable TLV area was found.

Returns

True if TLV area found, false otherwise.

operator<()

bool ts::TLVSyntax::operator< ( const TLVSyntax &  other ) const

inline

Comparison operator, typically used to sort containers of TLVSyntax.

Parameters

[in]

other

Other instance to compare.

Returns

True if this object logically preceeds other.

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

• tsTLVSyntax.h