Convenience routines to access a single component
[Low level access to single components]

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Detailed Description

Characteristic of these routines is that they perform a transformation between the user buffer and the data. In particular, the following is possible:

• Type conversions to/from float, int, short user buffer
• Signed user buffer with:
  • offset parameter
  • negation parameter
• Scaling parameter

As a result, these functions are not fast; their focus is on ease-of-use.

Typical use is a vector component with e.g. 2 bits subpixel precision that is stored in a floating point application buffer.

These functions are built upon the p_write_frame/field_comp_16() functions. They perform dynamic memory allocation using malloc()/free().

Most of the parameters are standard, the special ones are:

Parameters:

	field	0: frame, 1/2: field access.
	abuf	the pointer to the application buffer
	atype	type of the application buffer
	offset	zero value for signed data pfspd data is always unsigned, this specifies the pfspd value that maps to zero for signed appl buffers.
	gain	multiplication factor (may be negative)

When writing, an application value a is transformed into a pfspd value p:

  p = (unsigned short)((a * gain) + offset) 

When reading, the inverse transformation is:

  a = (p - offset) / (atype)gain    

When the component has type P_16_REAL_FILE, float and double values are converted to and from an internal 16-bit float format.

Functions
pT_status	p_cce_read_comp (const char *filename, pT_header *header, int frame, int field, int comp, void *abuf, pT_buf_type atype, int offset, int gain, int width, int height, int stride)
pT_status	p_cce_write_comp (const char *filename, pT_header *header, int frame, int field, int comp, const void *abuf, pT_buf_type atype, int offset, int gain, int width, int height, int stride)

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Function Documentation

pT_status p_cce_read_comp (  const char *  filename, pT_header *  header, int  frame, int  field, int  comp, void *  abuf, pT_buf_type  atype, int  offset, int  gain, int  width, int  height, int  stride )

pT_status p_cce_write_comp (  const char *  filename, pT_header *  header, int  frame, int  field, int  comp, const void *  abuf, pT_buf_type  atype, int  offset, int  gain, int  width, int  height, int  stride )

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