H264Decoder Class Reference

H.264 video decoder: wraps TinyH264Decoder (https://github.com/pschatzmann/TinyH264) as a VideoOutput, so it can be plugged directly into e.g. DemuxerAVI::setOutputVideo()/ DemuxerMP4::setOutputVideo(). Consumes an Annex-B H.264 bitstream via write() and, once a complete picture has been decoded, writes it - converted to setVideoFormat()'s format (RGB565 by default, the common TFT wire format) - to the Print target configured via setOutput(), one write() call per decoded picture. More...

#include <CodecH264.h>

Inheritance diagram for H264Decoder:

Public Member Functions
	H264Decoder ()
	H264Decoder (Print &out)
	H264Decoder (VideoOutput &out)
bool	begin () override
tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32< uint8_t > > &	driver ()
void	end () override
	Releases the decoder's picture buffers - see TinyH264Decoder::end().
void	flush () override
bool	hasError ()
void	setMaxRefFrames (int n)
void	setOutput (Print &out)
void	setOutput (VideoOutput &out)
void	setVideoFormat (VideoFormat format) override
VideoInfo	videoInfo () override
size_t	write (const uint8_t *data, size_t len) override

Protected Member Functions
void	writeToOutput ()
size_t	writeToOutput (uint8_t *data, size_t len)

Static Protected Member Functions
static void	onFrame (tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32< uint8_t > > &decoder, void *userData)

Protected Attributes
tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32< uint8_t > >	decoder_
Vector< uint8_t >	frame_buffer
Print *	p_out = nullptr
VideoOutput *	p_out_video = nullptr
VideoFormat	pixel_format = VideoFormat::RGB565

Detailed Description

H.264 video decoder: wraps TinyH264Decoder (https://github.com/pschatzmann/TinyH264) as a VideoOutput, so it can be plugged directly into e.g. DemuxerAVI::setOutputVideo()/ DemuxerMP4::setOutputVideo(). Consumes an Annex-B H.264 bitstream via write() and, once a complete picture has been decoded, writes it - converted to setVideoFormat()'s format (RGB565 by default, the common TFT wire format) - to the Print target configured via setOutput(), one write() call per decoded picture.

write()/flush() implement the VideoOutput contract (see Video.h): write() may be called one or more times per frame - bytes are forwarded to the decoder immediately (Annex-B start codes are self-delimiting, so no internal buffering is needed here; a picture may complete partway through any write() call, not just at flush()). flush() is a no-op, kept only because some producers (e.g. DemuxerAVI/DemuxerMP4) call it unconditionally after each frame.

Uses H264_DEFAULT_ALLOCATOR for the decoded picture buffers - see that macro's own comment above for the PSRAM-on-ESP32/heap- elsewhere default it picks, and how to override it.

Author

Phil Schatzmann

Copyright

GPLv3

Constructor & Destructor Documentation

H264Decoder() [1/3]

H264Decoder ( )

inline

H264Decoder() [2/3]

H264Decoder ( Print &  out )

inline

H264Decoder() [3/3]

H264Decoder ( VideoOutput &  out )

inline

Member Function Documentation

begin()

bool begin ( )

inlineoverridevirtual

Reserves the decoder's picture buffers up front - see TinyH264Decoder::begin().

Implements VideoDecoder.

driver()

tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32< uint8_t > > & driver ( )

inline

Direct access to the wrapped TinyH264Decoder, e.g. for its width()/ height()/y()/u()/v()/getY()/getU()/getV() accessors.

end()

void end ( )

inlineoverridevirtual

Releases the decoder's picture buffers - see TinyH264Decoder::end().

Implements VideoDecoder.

flush()

void flush ( )

inlineoverridevirtual

No-op - kept to satisfy the VideoOutput/Print contract; decoding already happens synchronously in write() (see class comment).

Reimplemented from VideoOutput.

hasError()

bool hasError ( )

inline

True if the most recent write() call ended in a bitstream error or hit an unsupported stream feature.

onFrame()

static void onFrame ( tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32< uint8_t > > &  decoder, void *  userData  )

inlinestaticprotected

setMaxRefFrames()

void setMaxRefFrames ( int  n )

inline

Runtime-active maximum stored reference pictures - see TinyH264Decoder::setMaxRefFrames().

setOutput() [1/2]

void setOutput ( Print &  out )

inlinevirtual

Defines the target the decoded picture is written to, one write() call per decoded picture, in the format selected via setVideoFormat() (RGB565 by default).

Implements VideoDecoder.

setOutput() [2/2]

void setOutput ( VideoOutput &  out )

inline

setVideoFormat()

void setVideoFormat ( VideoFormat  format )

inlineoverridevirtual

Selects the pixel format written to setOutput()'s target - RGB565 (the default) is what most TFT display libraries expect; RGB666/ RGB888 for higher color depth displays; I420 to pass the decoded planes through unconverted (tightly packed: Y bytes, then U bytes, then V bytes, no row padding - see TinyH264Decoder::toYUV420()). Any other VideoFormat is logged and ignored (previous format kept).

Implements VideoDecoder.

videoInfo()

VideoInfo videoInfo ( )

inlineoverridevirtual

Reports the format/dimensions of the picture written to setOutput()'s target - format is setVideoFormat()'s most recently selected value (RGB565 if never called); width/height are the most recently decoded picture's (0 before any picture has been decoded).

Implements VideoDecoder.

write()

size_t write ( const uint8_t *  data, size_t  len  )

inlineoverridevirtual

Feeds one chunk of Annex-B H.264 data - may be called more than once per frame (e.g. from a demuxer that hands over payload in pieces). Decodes immediately, invoking setOutput()'s Print once per completed picture from within this call (not deferred to flush()).

Implements VideoOutput.

writeToOutput() [1/2]

void writeToOutput ( )

inlineprotected

writeToOutput() [2/2]

size_t writeToOutput ( uint8_t *  data, size_t  len  )

inlineprotected

Member Data Documentation

decoder_

tinyh264::TinyH264Decoder< tinyh264::PSRAMAllocatorESP32<uint8_t> > decoder_

protected

frame_buffer

Vector<uint8_t> frame_buffer

protected

p_out

Print* p_out = nullptr

protected

p_out_video

VideoOutput* p_out_video = nullptr

protected

pixel_format

VideoFormat pixel_format = VideoFormat::RGB565

protected

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

• src/AudioTools/Video/CodecH264.h