Dirac - A Video Codec

Created by the British Broadcasting Corporation.


dirac_parser.h File Reference

C interface to Dirac decoder. More...

Include dependency graph for dirac_parser.h:

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Classes

struct  dirac_decoder_t

Typedefs

typedef DecoderState dirac_decoder_state_t

Functions

DllExport dirac_decoder_tdirac_decoder_init (int verbose)
DllExport void dirac_decoder_close (dirac_decoder_t *decoder)
DllExport dirac_decoder_state_t dirac_parse (dirac_decoder_t *decoder)
DllExport void dirac_buffer (dirac_decoder_t *decoder, unsigned char *start, unsigned char *end)
DllExport void dirac_set_buf (dirac_decoder_t *decoder, unsigned char *buf[3], void *id)

Detailed Description

A set of 'C' functions that define the public interface to the Dirac decoder. Refer to the the reference decoder source code, decoder/decmain.cpp for an example of how to use the "C" interface. The pseudocode below gives a brief description of the "C" interface usage.

 #include <libdirac_decoder/dirac_parser.h>\n
 Initialise the decoder

 dirac_decoder_t *decoder_handle = dirac_decoder_init();
 do
 {
     dirac_decoder_state_t state = dirac_parse (decoder_handle);
     switch (state)
     {
     case STATE_BUFFER:
         read more data.
         Pass data to the decoder.
         dirac_buffer (decoder_handle, data_start, data_end)
         break;

     case STATE_SEQUENCE:
         handle start of sequence.
         The decoder returns the sequence parameters in the 
         seq_params member of the decoder handle.
         Allocate space for the frame data buffers and pass 
         this to the decoder.
         dirac_set_buf (decoder_handle, buf, NULL);
         break;

     case STATE_SEQUENCE_END:
         Deallocate frame data buffers
         break;

     case STATE_PICTURE_AVAIL:
         Handle picture data.
         The decoder sets the fbuf member in the decoder 
         handle to the frame decoded.
         break;

     case STATE_INVALID:
         Unrecoverable error. Stop all processing
         break;
     }
 } while (data available && decoder state != STATE_INVALID
 
 Free the decoder resources
 dirac_decoder_close(decoder_handle)

Typedef Documentation

◆ dirac_decoder_state_t

Function Documentation

◆ dirac_buffer()

DllExport void dirac_buffer ( dirac_decoder_t * decoder,
unsigned char * start,
unsigned char * end )
extern

Copy data into internal buffer

Parameters
decoderDecoder object
startStart of data
endEnd of data

References DllExport.

◆ dirac_decoder_close()

DllExport void dirac_decoder_close ( dirac_decoder_t * decoder)
extern

Release the decoder resources

Parameters
decoderDecoder object

References DllExport.

◆ dirac_decoder_init()

DllExport dirac_decoder_t * dirac_decoder_init ( int verbose)
extern

Decoder Init Initialise the decoder.

Parameters
verboseboolean flag to set verbose output
Returns
decoder handle

References DllExport.

◆ dirac_parse()

DllExport dirac_decoder_state_t dirac_parse ( dirac_decoder_t * decoder)
extern

Parses the data in the input buffer. This function returns the following values.
STATE_BUFFER: Not enough data in internal buffer to process
STATE_SEQUENCE: Start of sequence detected. The seq_params member in the decoder object is set to the details of the next sequence to be processed.
STATE_PICTURE_START: Start of picture detected. The frame_params member of the decoder object is set to the details of the next frame to be processed.
STATE_PICTURE_AVAIL: Decoded picture available. The frame_aprams member of the decoder object is set the the details of the decoded frame available. The fbuf member of the decoder object has the luma and chroma data of the decompressed frame.
STATE_SEQUENCE_END: End of sequence detected.
STATE_INVALID: Invalid stream. Stop further processing.

Parameters
decoderDecoder object
Returns
Decoder state

References DllExport.

◆ dirac_set_buf()

DllExport void dirac_set_buf ( dirac_decoder_t * decoder,
unsigned char * buf[3],
void * id )
extern

Set the output buffer into which the decoder copies the decoded data

Parameters
decoderDecoder object
bufArray of char buffers to hold luma and chroma data
idUser data

References DllExport.


© 2004 British Broadcasting Corporation. Dirac code licensed under the Mozilla Public License (MPL) Version 1.1.
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