h264DecoderV4L2Helper Class Reference

#include <H264DecoderV4L2Helper.h>

Collaboration diagram for h264DecoderV4L2Helper:

Classes
struct	context_t

Public Member Functions
	h264DecoderV4L2Helper ()
	Struct defining the decoder context. The video decoder device node is /dev/nvhost-nvdec. The category name for the decoder is "NVDEC".
	~h264DecoderV4L2Helper ()
void	read_input_chunk_frame_sp (void *inputFrameBuffer, size_t inputFrameSize, Buffer *buffer)
	Reads the encoded data from a file to the buffer structure.
int	sendFrames (int dmaOutFrameFd, frame_sp outFrame)
	Writes a plane data of the buffer to a file.
int	set_capture_plane_format (context_t *ctx, uint32_t pixfmt, uint32_t width, uint32_t height)
	Sets the format on the decoder capture plane.
void	query_set_capture (context_t *ctx)
	Query and Set Capture plane.
bool	decode_process (context_t &ctx, void *inputFrameBuffer, size_t inputFrameSize)
	Decode processing function for blocking mode.
int	dq_event (context_t *ctx, struct v4l2_event &event, uint32_t max_wait_ms)
	Dequeues an event.
int	dq_buffer (context_t *ctx, struct v4l2_buffer &v4l2_buf, Buffer **buffer, enum v4l2_buf_type buf_type, enum v4l2_memory memory_type, uint32_t num_retries)
	Dequeues a buffer from the plane.
int	q_buffer (context_t *ctx, struct v4l2_buffer &v4l2_buf, Buffer *buffer, enum v4l2_buf_type buf_type, enum v4l2_memory memory_type, int num_planes)
	Queues a buffer on the plane.
int	req_buffers_on_capture_plane (context_t *ctx, enum v4l2_buf_type buf_type, enum v4l2_memory mem_type, int num_buffers)
	Requests for buffers on the decoder capture plane.
int	req_buffers_on_output_plane (context_t *ctx, enum v4l2_buf_type buf_type, enum v4l2_memory mem_type, int num_buffers)
	Requests for buffers on the decoder output plane.
int	set_output_plane_format (context_t &ctx, uint32_t pixfmt, uint32_t sizeimage)
	Sets the format on the decoder output plane.
int	set_ext_controls (int fd, uint32_t id, uint32_t value)
	Sets the value of controls.
int	subscribe_event (int fd, uint32_t type, uint32_t id, uint32_t flags)
	Subscribes to an V4L2 event.
int	process (void *inputFrameBuffer, size_t inputFrameSize, uint64_t inputFrameTS)
bool	init (std::function< void(frame_sp &)> send, std::function< frame_sp()> makeFrame)
bool	initializeDecoder ()
void	closeAllThreads (frame_sp eosFrame)
void	deQueAllBuffers ()

Static Public Member Functions
static void *	capture_thread (void *arg)
	Callback function on capture thread.

Protected Attributes
boost::shared_ptr< Buffer >	mBuffer
context_t	ctx
std::function< frame_sp()>	makeFrame
std::function< void(frame_sp &)>	send
int	ret = 0
std::queue< uint64_t >	framesTimestampEntry
std::mutex	m

Constructor & Destructor Documentation

h264DecoderV4L2Helper()

h264DecoderV4L2Helper::h264DecoderV4L2Helper ( )

inline

Struct defining the decoder context. The video decoder device node is /dev/nvhost-nvdec. The category name for the decoder is "NVDEC".

The context stores the information for decoding. Refer to V4L2 Video Decoder for more information on the decoder.

~h264DecoderV4L2Helper()

h264DecoderV4L2Helper::~h264DecoderV4L2Helper ( )

inline

Member Function Documentation

capture_thread()

void * h264DecoderV4L2Helper::capture_thread ( void * arg )

static

Callback function on capture thread.

This is a callback function of the capture loop thread created. the function runs infinitely until signaled to stop, or error is encountered.

Setting the stream to off automatically stops the thread.

Parameters

[in]

arg

A pointer to the application data.

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closeAllThreads()

void h264DecoderV4L2Helper::closeAllThreads

(

frame_sp

eosFrame

)

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decode_process()

bool h264DecoderV4L2Helper::decode_process	(	context_t &	ctx,
		void *	inputFrameBuffer,
		size_t	inputFrameSize )

Decode processing function for blocking mode.

Function loop to DQ and EnQ buffers on output plane till eos is signalled

Parameters

[in]

ctx

Reference to the decoder context struct created.

Returns

If the application implementing this call returns TRUE, EOS is detected by the decoder and all the buffers are dequeued; else the decode process continues running.

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deQueAllBuffers()

void h264DecoderV4L2Helper::deQueAllBuffers

(

)

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dq_buffer()

int h264DecoderV4L2Helper::dq_buffer	(	context_t *	ctx,
		struct v4l2_buffer &	v4l2_buf,
		Buffer **	buffer,
		enum v4l2_buf_type	buf_type,
		enum v4l2_memory	memory_type,
		uint32_t	num_retries )

Dequeues a buffer from the plane.

This method calls VIDIOC_DQBUF IOCTL internally. This is a blocking call. This call returns when a buffer is successfully dequeued or timeout is reached. If the buffer is not NULL, returns the Buffer object at the index returned by VIDIOC_DQBUF IOCTL

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in]	v4l2_buf	A reference to the v4l2_buffer structure to use for dequeueing.
[in]	buffer	A double pointer to the Buffer object associated with the dequeued buffer. Can be NULL.
[in]	buf_type	Type of buffer, one of the enum v4l2_buf_type.
[in]	mem_type	Memory type of the plane, one of the enum v4l2_memory mem_type
[in]	num_retries	Number of times to try dequeuing a buffer before a failure is returned.

Returns

0 for success, -1 otherwise.

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dq_event()

int h264DecoderV4L2Helper::dq_event	(	context_t *	ctx,
		struct v4l2_event &	event,
		uint32_t	max_wait_ms )

Dequeues an event.

Calls VIDIOC_DQEVENT IOCTL internally. This is a blocking call. The call returns when an event is successfully dequeued or timeout is reached.

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in,out]	event	A reference to the v4l2_event structure to fill.
[in]	max_wait_ms	Specifies the max wait time for dequeuing an event, in milliseconds.

Returns

0 for success, -1 otherwise.

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init()

bool h264DecoderV4L2Helper::init	(	std::function< void(frame_sp &)>	send,
		std::function< frame_sp()>	makeFrame )

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initializeDecoder()

bool h264DecoderV4L2Helper::initializeDecoder

(

)

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process()

int h264DecoderV4L2Helper::process	(	void *	inputFrameBuffer,
		size_t	inputFrameSize,
		uint64_t	inputFrameTS )

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q_buffer()

int h264DecoderV4L2Helper::q_buffer	(	context_t *	ctx,
		struct v4l2_buffer &	v4l2_buf,
		Buffer *	buffer,
		enum v4l2_buf_type	buf_type,
		enum v4l2_memory	memory_type,
		int	num_planes )

Queues a buffer on the plane.

This method calls VIDIOC_QBUF IOCTL internally.

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in]	v4l2_buf	A reference to the v4l2_buffer structure to use for queueing.
[in]	buffer	A pointer to the Buffer object.
[in]	buf_type	Type of buffer, one of the enum v4l2_buf_type.
[in]	mem_type	Memory type of the plane, one of the enum v4l2_memory mem_type
[in]	num_planes	Number of planes in the buffer.

Returns

0 for success, -1 otherwise.

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query_set_capture()

void h264DecoderV4L2Helper::query_set_capture

(

context_t *

ctx

)

Query and Set Capture plane.

On successful dqevent, this method sets capture plane properties, buffers and streaming status.

Parameters

[in]

ctx

Pointer to the decoder context struct created.

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read_input_chunk_frame_sp()

void h264DecoderV4L2Helper::read_input_chunk_frame_sp	(	void *	inputFrameBuffer,
		size_t	inputFrameSize,
		Buffer *	buffer )

Reads the encoded data from a file to the buffer structure.

Helper function to read the filestream to mmaped buffer

Parameters

[in]	stream	Input stream
[in]	buffer	Buffer class pointer

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req_buffers_on_capture_plane()

int h264DecoderV4L2Helper::req_buffers_on_capture_plane	(	context_t *	ctx,
		enum v4l2_buf_type	buf_type,
		enum v4l2_memory	mem_type,
		int	num_buffers )

Requests for buffers on the decoder capture plane.

Calls the VIDIOC_REQBUFS IOCTL internally on the capture plane.

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in]	buf_type	Type of buffer, one of the enum v4l2_buf_type.
[in]	mem_type	Memory type of the plane, one of the enum v4l2_memory mem_type, here V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
[in]	num_buffers	Number of buffers to be requested.

Returns

0 for success, -1 otherwise.

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req_buffers_on_output_plane()

int h264DecoderV4L2Helper::req_buffers_on_output_plane	(	context_t *	ctx,
		enum v4l2_buf_type	buf_type,
		enum v4l2_memory	mem_type,
		int	num_buffers )

Requests for buffers on the decoder output plane.

Calls the VIDIOC_REQBUFS IOCTL internally on the output plane.

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in]	buf_type	Type of buffer, one of the enum v4l2_buf_type.
[in]	mem_type	Memory type of the plane, one of the enum v4l2_memory mem_type, here V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
[in]	num_buffers	Number of buffers to be requested.

Returns

0 for success, -1 otherwise.

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sendFrames()

int h264DecoderV4L2Helper::sendFrames	(	int	dmaOutFrameFd,
		frame_sp	outputFrame )

Writes a plane data of the buffer to a file.

This function writes data into the file from a plane of the DMA buffer.

Parameters

[in]	dmabuf_fd	DMABUF FD of buffer.
[in]	plane	video frame plane.
[in]	stream	A pointer to the output file stream.

Returns

0 for success, -1 otherwise.

This function writes the video frame from the HW buffer exported as FD into the destination file. Using the FD, HW buffer parameters are filled by calling NvBufferGetParams. The parameters received from the buffer are then used to read the planar stream from the HW buffer into the output filestream.

For reading from the HW buffer: A void data-pointer is created which stores the memory-mapped virtual addresses of the planes. For each plane, NvBufferMemMap is called which gets the memory-mapped virtual address of the plane with the access pointed by the flag into the void data-pointer. Before the mapped memory is accessed, a call to NvBufferMemSyncForCpu() with the virtual address returned must be present before any access is made by the CPU to the buffer.

After reading the data, the memory-mapped virtual address of the plane is unmapped.

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set_capture_plane_format()

int h264DecoderV4L2Helper::set_capture_plane_format	(	context_t *	ctx,
		uint32_t	pixfmt,
		uint32_t	width,
		uint32_t	height )

Sets the format on the decoder capture plane.

Calls the VIDIOC_S_FMT IOCTL internally on the capture plane.

Parameters

[in]	ctx	Pointer to the decoder context struct created.
[in]	pixfmt	One of the coded V4L2 pixel formats.
[in]	width	Width of the frame
[in]	height	Height of the frame

Returns

0 for success, -1 otherwise.

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set_ext_controls()

int h264DecoderV4L2Helper::set_ext_controls	(	int	fd,
		uint32_t	id,
		uint32_t	value )

Sets the value of controls.

Calls the VIDIOC_S_EXT_CTRLS IOCTL internally with Control ID as an input.

Parameters

[in]	fd	context FD
[in]	id	control id
[in]	value	control value

Returns

0 for success, -1 otherwise.

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set_output_plane_format()

int h264DecoderV4L2Helper::set_output_plane_format	(	context_t &	ctx,
		uint32_t	pixfmt,
		uint32_t	sizeimage )

Sets the format on the decoder output plane.

Calls the VIDIOC_S_FMT IOCTL internally on the output plane.

Parameters

[in]	ctx	Reference to the decoder context struct created.
[in]	pixfmt	One of the coded V4L2 pixel formats.
[in]	sizeimage	Maximum size of the buffers on the output plane. containing encoded data in bytes.

Returns

0 for success, -1 otherwise.

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subscribe_event()

int h264DecoderV4L2Helper::subscribe_event	(	int	fd,
		uint32_t	type,
		uint32_t	id,
		uint32_t	flags )

Subscribes to an V4L2 event.

Calls the VIDIOC_SUBSCRIBE_EVENT IOCTL internally

Parameters

[in]	fd	context FD
[in]	type	Type of the event
[in]	id	ID of the event source
[in]	flags	Event flags

Returns

0 for success, -1 otherwise.

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Member Data Documentation

ctx

context_t h264DecoderV4L2Helper::ctx

protected

framesTimestampEntry

std::queue<uint64_t> h264DecoderV4L2Helper::framesTimestampEntry

protected

m

std::mutex h264DecoderV4L2Helper::m

protected

makeFrame

std::function<frame_sp()> h264DecoderV4L2Helper::makeFrame

protected

mBuffer

boost::shared_ptr<Buffer> h264DecoderV4L2Helper::mBuffer

protected

ret

int h264DecoderV4L2Helper::ret = 0

protected

send

std::function<void(frame_sp &)> h264DecoderV4L2Helper::send

protected

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

• base/src/H264DecoderV4L2Helper.h
• base/src/H264DecoderV4L2Helper.cpp