NvJPEGDecoder Class Reference

Detailed Description

Helper class for decoding JPEG images using libjpeg APIs.

NvJPEGDecoder uses the libjpeg APIs for decoding JPEG images. It supports two methods for decoding:

• Decode to a DMABUF and return its file descriptor (FD).
• Decode and write data to a NvBuffer object, i.e., software allocated memory (malloc).

The JPEG decoder is capable of decoding YUV420, YUV422, and YUV444 JPEG images.

Note

Only the JCS_YCbCr (YUV420) color space is currently supported.

Definition at line 86 of file NvJpegDecoder.h.

Inheritance diagram for NvJPEGDecoder:

Collaboration diagram for NvJPEGDecoder:

Public Member Functions
	~NvJPEGDecoder ()
int	decodeToFd (int &fd, unsigned char *in_buf, unsigned long in_buf_size, uint32_t &pixfmt, uint32_t &width, uint32_t &height)
	Decodes a JPEG image to hardware buffer memory. More...
int	decodeToBuffer (NvBuffer **buffer, unsigned char *in_buf, unsigned long in_buf_size, uint32_t *pixfmt, uint32_t *width, uint32_t *height)
	Decodes a JPEG image to software buffer memory. More...
virtual int	isInError ()
	Indicates whether the element encountered an error during its operation. More...
void	getProfilingData (NvElementProfiler::NvElementProfilerData &data)
	Gets profiling data for the element. More...
void	printProfilingStats (std::ostream &out_stream=std::cout)
	Prints profiling data for the element to an output stream. More...
virtual void	enableProfiling ()
	Enables profiling for the element. More...
bool	isProfilingEnabled ()
	Checks whether profiling is enabled for the element. More...

Static Public Member Functions
static NvJPEGDecoder *	createJPEGDecoder (const char *comp_name)
	Creates a new JPEG Decoder named comp_name. More...

Protected Attributes
int	is_in_error
	Indicates if an error was encountered during the operation of the element. More...
const char *	comp_name
	Specifies the name of the component, for debugging. More...
NvElementProfiler	profiler
	Profiler for the element. More...

Constructor & Destructor Documentation

~NvJPEGDecoder()

NvJPEGDecoder::~NvJPEGDecoder

(

)

Member Function Documentation

createJPEGDecoder()

static NvJPEGDecoder* NvJPEGDecoder::createJPEGDecoder ( const char *  comp_name )

static

Creates a new JPEG Decoder named comp_name.

Returns

Reference to the newly created decoder object, or NULL in case of failure during initialization.

decodeToBuffer()

int NvJPEGDecoder::decodeToBuffer	(	NvBuffer **	buffer,
		unsigned char *	in_buf,
		unsigned long	in_buf_size,
		uint32_t *	pixfmt,
		uint32_t *	width,
		uint32_t *	height
	)

Decodes a JPEG image to software buffer memory.

This method decodes JPEG images in software memory to a specified width and size.

Note

The decodeToBuffer method is slower than the NvJPEGDecoder::decodeToFd method because it involves conversion from hardware buffer memory to software buffer memory.

Attention

The application must free the NvBuffer object.

Parameters

[out]	buffer	Indirect pointer to an NvBuffer object that contains the decoded image. The object is allocated by the method and the buffer memory is allocated using NvBuffer::allocateMemory.
[in]	in_buf	A pointer to the memory containing the JPEG.
[in]	in_buf_size	Size of the input buffer in bytes.
[out]	pixfmt	A pointer to the V4L2 pixel format of the decoded image.
[out]	width	A pointer to the width of the decoded image in pixels.
[out]	height	A pointer to the height of the decoded image in pixels.

Returns

0 for success, -1 otherwise.

decodeToFd()

int NvJPEGDecoder::decodeToFd	(	int &	fd,
		unsigned char *	in_buf,
		unsigned long	in_buf_size,
		uint32_t &	pixfmt,
		uint32_t &	width,
		uint32_t &	height
	)

Decodes a JPEG image to hardware buffer memory.

This method decodes JPEG images in hardware memory to a specified width and size.

Parameters

[out]	fd	A reference to the file descriptor (FD) of the hardware buffer.
[in]	in_buf	A pointer to the memory containing the JPEG image.
[in]	in_buf_size	Size of the input buffer in bytes.
[out]	pixfmt	A reference to the V4L2 pixel format of the decoded image.
[out]	width	A reference to the width of the decoded image in pixels.
[out]	height	A reference to the height of the decoded image in pixels.

Returns

0 for success, -1 otherwise.

enableProfiling()

virtual void NvElement::enableProfiling ( )

virtualinherited

Enables profiling for the element.

Reimplemented in NvV4l2Element.

getProfilingData()

void NvElement::getProfilingData ( NvElementProfiler::NvElementProfilerData &  data )

inherited

Gets profiling data for the element.

Returns

A constant reference to the element's profiling data.

isInError()

virtual int NvElement::isInError ( )

inlinevirtualinherited

Indicates whether the element encountered an error during its operation.

Returns

0 if no error was encountered, a non-zero value if an error was encountered.

Reimplemented in NvV4l2Element.

Definition at line 72 of file NvElement.h.

References NvElement::is_in_error.

isProfilingEnabled()

bool NvElement::isProfilingEnabled ( )

inherited

Checks whether profiling is enabled for the element.

Returns

Boolean value indicating if profiling is enabled.

printProfilingStats()

void NvElement::printProfilingStats ( std::ostream &  out_stream = std::cout )

inherited

Prints profiling data for the element to an output stream.

Parameters

[in]

out_stream

Output stream of type std::ostream to print the data to. It takes the default value std::cout if not specified.

Field Documentation

comp_name

const char* NvElement::comp_name

protectedinherited

Specifies the name of the component, for debugging.

Definition at line 122 of file NvElement.h.

is_in_error

int NvElement::is_in_error

protectedinherited

Indicates if an error was encountered during the operation of the element.

Definition at line 120 of file NvElement.h.

Referenced by NvElement::isInError().

profiler

NvElementProfiler NvElement::profiler

protectedinherited

Profiler for the element.

Definition at line 124 of file NvElement.h.

---

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

• multimedia_api/ll_samples/include/NvJpegDecoder.h