MJPEGEncoder Class Reference

Motion-JPEG video encoder: wraps TinyJPEGEncoder (https://github.com/pschatzmann/TinyJPEG) as a VideoEncoder - the MJPEG counterpart of H264Encoder (CodecH264.h), e.g. for VideoMuxer/ VideoMuxerWithTasks with a camera that delivers raw pictures. Configure it via setSize()/setVideoFormat() (RGB565 - the default -, RGB888 or RGB666, packed) and optionally setQuality()/setSubsample(), then feed raw pictures via write(): each one is encoded into one complete JPEG image, which is written to the target configured via setOutput() in a single write() call - as the muxers expect one frame per call. More...

#include <CodecJPEG.h>

Inheritance diagram for MJPEGEncoder:

Public Member Functions
	MJPEGEncoder (int width=0, int height=0)
	MJPEGEncoder (Print &out)
	MJPEGEncoder (VideoOutput &out)
bool	begin () override
	Initializes the encoder (allocates its picture buffers, etc).
tinyjpeg::TinyJPEGEncoder &	driver ()
	Direct access to the wrapped TinyJPEGEncoder.
void	end () override
	Releases the encoder's resources.
void	setBufferSize (size_t size)
void	setOutput (Print &out) override
	Defines the target each encoded JPEG image is written to.
void	setOutput (VideoOutput &out)
void	setQuality (uint8_t quality)
	JPEG quality: 1 (smallest) to 100 (best) - see TinyJPEGEncoder::setQuality()
void	setSize (int width, int height)
	Defines the picture size.
void	setSubsample (bool enable)
	4:2:0 chroma subsampling on/off - see TinyJPEGEncoder::setSubsample()
void	setVideoFormat (VideoFormat format) override
VideoInfo	videoInfo () override
	Reports VideoFormat::MJPEG and the size set via setSize().
size_t	write (const uint8_t *data, size_t len) override

Static Public Attributes
static constexpr size_t	kDefaultBufferSize = 16384
	Default size (bytes) of the internal JPEG buffer - see setBufferSize().

Protected Member Functions
JERESULT	encode (const uint8_t *data, size_t &size)

Protected Attributes
tinyjpeg::TinyJPEGEncoder	encoder_
int	height_ = 0
VideoFormat	input_format = VideoFormat::RGB565
Vector< uint8_t >	jpeg
Print *	p_out = nullptr
VideoOutput *	p_out_video = nullptr
int	width_ = 0

Static Protected Attributes
static constexpr int	kMaxGrowRetries = 4
	Number of times the buffer is doubled before giving up.

Detailed Description

Motion-JPEG video encoder: wraps TinyJPEGEncoder (https://github.com/pschatzmann/TinyJPEG) as a VideoEncoder - the MJPEG counterpart of H264Encoder (CodecH264.h), e.g. for VideoMuxer/ VideoMuxerWithTasks with a camera that delivers raw pictures. Configure it via setSize()/setVideoFormat() (RGB565 - the default -, RGB888 or RGB666, packed) and optionally setQuality()/setSubsample(), then feed raw pictures via write(): each one is encoded into one complete JPEG image, which is written to the target configured via setOutput() in a single write() call - as the muxers expect one frame per call.

The encoded image is assembled in an internal buffer, which starts at kDefaultBufferSize and grows (doubling, up to a few attempts) whenever an image doesn't fit - so it doesn't need to be sized by hand; use setBufferSize() to pre-size it.

Author

Phil Schatzmann

Copyright

GPLv3

Constructor & Destructor Documentation

MJPEGEncoder() [1/3]

MJPEGEncoder ( int  width = 0, int  height = 0  )

inline

MJPEGEncoder() [2/3]

MJPEGEncoder ( Print &  out )

inline

MJPEGEncoder() [3/3]

MJPEGEncoder ( VideoOutput &  out )

inline

Member Function Documentation

begin()

bool begin ( )

inlineoverridevirtual

Initializes the encoder (allocates its picture buffers, etc).

Implements VideoEncoder.

driver()

tinyjpeg::TinyJPEGEncoder & driver ( )

inline

Direct access to the wrapped TinyJPEGEncoder.

encode()

JERESULT encode ( const uint8_t *  data, size_t &  size  )

inlineprotected

end()

void end ( )

inlineoverridevirtual

Releases the encoder's resources.

Implements VideoEncoder.

setBufferSize()

void setBufferSize ( size_t  size )

inline

Pre-sizes the internal JPEG buffer (see class comment). Shrinks are ignored.

setOutput() [1/2]

void setOutput ( Print &  out )

inlineoverridevirtual

Defines the target each encoded JPEG image is written to.

Implements VideoEncoder.

setOutput() [2/2]

void setOutput ( VideoOutput &  out )

inline

setQuality()

void setQuality ( uint8_t  quality )

inline

JPEG quality: 1 (smallest) to 100 (best) - see TinyJPEGEncoder::setQuality()

setSize()

void setSize ( int  width, int  height  )

inline

Defines the picture size.

setSubsample()

void setSubsample ( bool  enable )

inline

4:2:0 chroma subsampling on/off - see TinyJPEGEncoder::setSubsample()

setVideoFormat()

void setVideoFormat ( VideoFormat  format )

inlineoverridevirtual

Selects the raw picture format write() expects: VideoFormat::RGB565 (the default), RGB888 or RGB666 (packed). Any other format is logged and ignored (previous format kept).

Implements VideoEncoder.

videoInfo()

VideoInfo videoInfo ( )

inlineoverridevirtual

Reports VideoFormat::MJPEG and the size set via setSize().

Implements VideoEncoder.

write()

size_t write ( const uint8_t *  data, size_t  len  )

inlineoverridevirtual

Encodes one raw picture (setVideoFormat()'s format, setSize()'s size) and writes the JPEG image to the output - returns its size (0 if nothing was written, e.g. if len doesn't match the configured format and size).

Implements VideoEncoder.

Member Data Documentation

encoder_

tinyjpeg::TinyJPEGEncoder encoder_

protected

height_

int height_ = 0

protected

input_format

VideoFormat input_format = VideoFormat::RGB565

protected

jpeg

Vector<uint8_t> jpeg

protected

kDefaultBufferSize

constexpr size_t kDefaultBufferSize = 16384

staticconstexpr

Default size (bytes) of the internal JPEG buffer - see setBufferSize().

kMaxGrowRetries

constexpr int kMaxGrowRetries = 4

staticconstexprprotected

Number of times the buffer is doubled before giving up.

p_out

Print* p_out = nullptr

protected

p_out_video

VideoOutput* p_out_video = nullptr

protected

width_

int width_ = 0

protected

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

• src/AudioTools/Video/CodecJPEG.h