qccchannelread.3

spiht for linux this is used to decod and encode vedio i wich all enjoy

.TH QCCCHANNELREAD 3 "QCCPACK" ""
.SH NAME
QccChannelReadWholefile,
QccChannelReadHeader,
QccChannelStartRead,
QccChannelEndRead,
QccChannelReadBlock
\- reading of QccChannel structures from CHN-format files
.SH SYNOPSIS
.B #include "libQccPack.h"
.sp
.BI "int QccChannelReadWholefile(QccChannel *" channel );
.br
.BI "int QccChannelReadHeader(QccChannel *" channel );
.br
.BI "int QccChannelStartRead(QccChannel *" channel );
.br
.BI "int QccChannelEndRead(QccChannel *" channel );
.br
.BI "int QccChannelReadBlock(QccChannel *" channel );
.SH DESCRIPTION
These routines implement the reading of
.B QccChannel
channels from
.BR CHN -format
files.
There are two distinct modes in which the channel-symbol data
in channels may be read:
the whole file may be read at once, or
the file may be read in non-overlapping blocks.
.LP
.B QccChannelReadWholefile()
reads the
.BR CHN -format
file whose filename is given by
.IR channel -> filename .
The entire file is read, including the header,
and the symbols are returned in the 
.IR channel -> channel_symbols .
If 
.IR channel -> channel_symbols
is
.BR NULL ,
.IR channel -> channel_symbols
is allocated via a call to
.B QccChannelAlloc() 
prior to reading;
otherwise, it is assumed that sufficient space has already been allocated.
.LP
.B QccChannelReadHeader()
reads the header information of the
.BR CHN -format
file pointed to by
.IR channel -> fileptr ,
which must be already open and positioned at the start of the file.
Information read from the header is returned in the fields of
.IR channel .
.LP
.B QccChannelStartRead()
must be called before any block-based read of
.IR channel .
.B QccChannelStartRead()
opens the file with 
.BR QccFileOpen (3),
reads the file's header with
.BR QccChannelReadHeader (3),
and allocates storage space, if needed, for the
channel symbols by calling
.BR QccChannelAlloc (3)
(note that allocation is performed only if 
.IR channel -> channel_symbols
is 
.BR NULL).
Prior to calling
.BR QccChannelStartRead() ,
.IR channel -> filename
must contain the name of the file and
.IR channel -> access_block_size
must give the block size desired for subsequent block-based reads.
The remaining fields of
.I channel
are filled in from the file's header.
After
.B QccChannelStartRead()
returns,
.IR channel -> fileptr
contains the
.B FILE
pointer to the open file, and the file
is positioned at the start of the channel-symbol data, ready for reading the
first block of symbols.
.LP
.B QccChannelEndRead()
closes a channel file opened by a previous call to
.BR QccChannelStartRead() ;
additionally, the symbol array,
.IR channel -> channel_symbols ,
is freed with a call to 
.BR QccChannelFree (3).
.LP
.B QccChannelReadBlock()
reads the next block of symbols in the channel.
.I channel
must be prepared by a prior call to
.BR QccChannelStartRead() ;
that is, 
.IR channel -> fileptr
must point to an open file,
.IR channel -> access_block_size
must contain the size of the block of symbols to read,
and
.IR channel -> channel_symbols
must be allocated with space sufficient for storing
the block of symbols.
.B QccChannelReadBlock()
reads non-overlapping blocks of data from the file;
after
.B QccChannelReadBlock()
returns, the file is positioned at the start of the subsequent block.
.SH "RETURN VALUE"
These routines return 0 on successful completion, 1 if an error occurs
while reading the file.
.SH "SEE ALSO"
.BR QccChannelWrite (3),
.BR QccChannel (3),
.BR QccFileOpen (3),
.BR QccChannel (3),
.BR QccPack (3)
.SH AUTHOR
Copyright (C) 1997-2009  James E. Fowler
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