LtcDecoder Class Reference

Decodes LTC (Linear Timecode) audio samples into timecode values. More...

#include <ltcdecoder.h>

Classes
struct	DecodedTimecode
	Result of decoding a single LTC frame. More...

Public Types
using	DecodedList = List< DecodedTimecode >
	List of decoded timecode results.

Public Member Functions
	LtcDecoder (int sampleRate)
	Constructs an LTC decoder.
	~LtcDecoder ()=default
	Destructor.
	LtcDecoder (const LtcDecoder &)=delete
LtcDecoder &	operator= (const LtcDecoder &)=delete
	LtcDecoder (LtcDecoder &&)=default
LtcDecoder &	operator= (LtcDecoder &&)=default
int	sampleRate () const
	Returns the configured sample rate.
void	setThresholds (int8_t lower, int8_t upper)
	Sets the hysteresis thresholds for edge detection.
void	setFuzz (int fuzz)
	Sets the timing tolerance in samples.
DecodedList	decode (const int8_t *samples, size_t count)
	Feeds raw int8_t audio samples to the decoder.
DecodedList	decode (const Audio &audio)
	Feeds an Audio object to the decoder.
void	reset ()
	Clears the decoder state.

Detailed Description

Decodes LTC (Linear Timecode) audio samples into timecode values.

Wraps libvtc's VtcLTCDecoder to extract SMPTE timecode from biphase-mark-encoded audio. Supports incremental decoding (audio can be fed in chunks) and detects forward/reverse playback direction.

Not copyable (owns decoder state). Movable.

Example

LtcDecoder dec(48000);
auto results = dec.decode(audioSamples, sampleCount);
for(auto &r : results) {
    // r.timecode is the decoded value
}

Constructor & Destructor Documentation

LtcDecoder()

LtcDecoder::LtcDecoder

(

int

sampleRate

)

Constructs an LTC decoder.

Parameters

sampleRate

Audio sample rate (e.g. 48000).

Member Function Documentation

decode() [1/2]

DecodedList LtcDecoder::decode

(

const Audio &

audio

)

Feeds an Audio object to the decoder.

The Audio must be mono PCMI_S8. Other formats are not supported.

Parameters

audio

The audio to decode.

Returns

List of decoded timecodes found in this chunk.

decode() [2/2]

DecodedList LtcDecoder::decode	(	const int8_t *	samples,
		size_t	count
	)

Feeds raw int8_t audio samples to the decoder.

Parameters

samples	Pointer to int8_t audio data.
count	Number of samples.

Returns

List of decoded timecodes found in this chunk.

reset()

void LtcDecoder::reset

(

)

Clears the decoder state.

Use after seeking or switching sources.

sampleRate()

int LtcDecoder::sampleRate ( ) const

inline

Returns the configured sample rate.

Returns

The sample rate in Hz.

setFuzz()

void LtcDecoder::setFuzz

(

int

fuzz

)

Sets the timing tolerance in samples.

Parameters

fuzz	Fuzz tolerance (default: 3).

setThresholds()

void LtcDecoder::setThresholds	(	int8_t	lower,
		int8_t	upper
	)

Sets the hysteresis thresholds for edge detection.

Parameters

lower	Lower threshold (typically negative, e.g. -3).
upper	Upper threshold (typically positive, e.g. 3).

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

• include/promeki/proav/ltcdecoder.h