ts::TimeShiftBuffer Class Reference

A TS packet buffer for time shift. More...

Public Member Functions
	TimeShiftBuffer (size_t count=DEFAULT_TOTAL_PACKETS)
	Constructor. More...
virtual	~TimeShiftBuffer ()
	Destructor.
bool	close (Report &report)
	Close the buffer. More...
size_t	count () const
	Get the current number of packets in the time-shift buffer. More...
bool	empty () const
	Check if the buffer is empty. More...
bool	full () const
	Check if the buffer is full. More...
bool	isOpen () const
	Check if the buffer is open. More...
bool	memoryResident () const
	Check if the buffer is completely memory resident. More...
bool	open (Report &report)
	Open the buffer. More...
bool	setBackupDirectory (const UString &directory)
	Set the directory for the backup file on disk. More...
bool	setMemoryPackets (size_t count)
	Set the maximum number of cached packets to be held in memory. More...
bool	setTotalPackets (size_t count)
	Set the total size of the time shift buffer in packets. More...
bool	shift (TSPacket &packet, TSPacketMetadata &metadata, Report &report)
	Push a packet in the time-shift buffer and pull the oldest one. More...
size_t	size () const
	Get the total size in packets of the time-shift buffer. More...

Static Public Attributes
static constexpr size_t	DEFAULT_MEMORY_PACKETS = 128
	Default number of cached packets in memory.
static constexpr size_t	DEFAULT_TOTAL_PACKETS = 128
	Default size in packets of a time shift buffer.
static constexpr size_t	MIN_MEMORY_PACKETS = 2
	Minimum number of cached packets in memory.
static constexpr size_t	MIN_TOTAL_PACKETS = 2
	Minimum size in packets of a time shift buffer.

Detailed Description

A TS packet buffer for time shift.

The buffer is partly implemented in virtual memory and partly on disk.

Constructor & Destructor Documentation

TimeShiftBuffer()

ts::TimeShiftBuffer::TimeShiftBuffer

(

size_t

count = DEFAULT_TOTAL_PACKETS

)

Constructor.

Parameters

[in]

count

Max number of packets in the buffer.

Member Function Documentation

setTotalPackets()

bool ts::TimeShiftBuffer::setTotalPackets

(

size_t

count

)

Set the total size of the time shift buffer in packets.

Must be called before open().

Parameters

[in]

count

Max number of packets in the buffer.

Returns

True on success, false if already open.

setMemoryPackets()

bool ts::TimeShiftBuffer::setMemoryPackets

(

size_t

count

)

Set the maximum number of cached packets to be held in memory.

Must be called before open().

Parameters

[in]

count

Max number of cached packets in memory.

Returns

True on success, false if already open.

setBackupDirectory()

bool ts::TimeShiftBuffer::setBackupDirectory

(

const UString &

directory

)

Set the directory for the backup file on disk.

Must be called before open(). By default, the file is created in the system-dependent temporary directory. When the maximum number of cached packets in memory is larger than the buffer size, the buffer is entirely resident in memory and no file is created. The back file is automatically deleted when the time-shift buffer is closed.

Parameters

[in]

directory

Directory name.

Returns

True on success, false if already open or too small.

open()

bool ts::TimeShiftBuffer::open

(

Report &

report

)

Open the buffer.

Parameters

[in,out]

report

Where to report errors.

Returns

True on success, false on error.

close()

bool ts::TimeShiftBuffer::close

(

Report &

report

)

Close the buffer.

The memory is freed and the disk backup file is deleted.

Parameters

[in,out]

report

Where to report errors.

Returns

True on success, false on error.

isOpen()

bool ts::TimeShiftBuffer::isOpen ( ) const

inline

Check if the buffer is open.

Returns

True if the buffer is open.

size()

size_t ts::TimeShiftBuffer::size ( ) const

inline

Get the total size in packets of the time-shift buffer.

Returns

The total size in packets of the time-shift buffer.

count()

size_t ts::TimeShiftBuffer::count ( ) const

inline

Get the current number of packets in the time-shift buffer.

Returns

The current number of packets in the time-shift buffer.

empty()

bool ts::TimeShiftBuffer::empty ( ) const

inline

Check if the buffer is empty.

Returns

True when the buffer is empty, false otherwise.

full()

bool ts::TimeShiftBuffer::full ( ) const

inline

Check if the buffer is full.

Returns

True when the buffer is full, false otherwise.

memoryResident()

bool ts::TimeShiftBuffer::memoryResident ( ) const

inline

Check if the buffer is completely memory resident.

Returns

True when the buffer is memory resident, false when it is backup by a file.

shift()

bool ts::TimeShiftBuffer::shift	(	TSPacket &	packet,
		TSPacketMetadata &	metadata,
		Report &	report
	)

Push a packet in the time-shift buffer and pull the oldest one.

As long as the buffer is not full, a null packet is returned. When the buffer is full, the oldest packet is returned and removed from the buffer. Initial null packets which are generated while the time-shift buffer is filling can be recognized as they are marked as "input stuffing" in their metadata, after returning from shift().

Parameters

[in,out]	packet	On input, contains the packet to push. On output, contains the time-shifted packet.
[in,out]	metadata	Packet metadata.
[in,out]	report	Where to report errors.

Returns

True on success, false on error.

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

• tsTimeShiftBuffer.h