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| author | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 18:28:40 -0800 |
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| committer | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 18:28:40 -0800 |
| commit | 9260d09499b620470f639ec024af8ee6ac18bf64 (patch) | |
| tree | 4b825dc642cb6eb9a060e54bf8d69288fbee4904 /Tremor/doc/callbacks.html | |
| parent | 0ad0141e864cfbb130db4f22e279d421832e7336 (diff) | |
| download | tremor-9260d09499b620470f639ec024af8ee6ac18bf64.tar.gz | |
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diff --git a/Tremor/doc/callbacks.html b/Tremor/doc/callbacks.html deleted file mode 100644 index 9a6d392..0000000 --- a/Tremor/doc/callbacks.html +++ /dev/null @@ -1,113 +0,0 @@ -<html> - -<head> -<title>Tremor - Callbacks and non-stdio I/O</title> -<link rel=stylesheet href="style.css" type="text/css"> -</head> - -<body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> -<table border=0 width=100%> -<tr> -<td><p class=tiny>Tremor documentation</p></td> -<td align=right><p class=tiny>Tremor version 1.0 - 20020403</p></td> -</tr> -</table> - -<h1>Callbacks and non-stdio I/O</h1> - -Although stdio is convenient and nearly universally implemented as per -ANSI C, it is not suited to all or even most potential uses of Vorbis. -For additional flexibility, embedded applications may provide their -own I/O functions for use with Tremor when stdio is unavailable or not -suitable. One common example is decoding a Vorbis stream from a -memory buffer.<p> - -Use custom I/O functions by populating an <a -href="ov_callbacks.html">ov_callbacks</a> structure and calling <a -href="ov_open_callbacks.html">ov_open_callbacks()</a> or <a -href="ov_test_callbacks.html">ov_test_callbacks()</a> rather than the -typical <a href="ov_open.html">ov_open()</a> or <a -href="ov_test.html">ov_test()</a>. Past the open call, use of -libvorbisidec is identical to using it with stdio. - -<h2>Read function</h2> - -The read-like function provided in the <tt>read_func</tt> field is -used to fetch the requested amount of data. It expects the fetch -operation to function similar to file-access, that is, a multiple read -operations will retrieve contiguous sequential pieces of data, -advancing a position cursor after each read.<p> - -The following behaviors are also expected:<p> -<ul> -<li>a return of '0' indicates end-of-data (if the by-thread errno is unset) -<li>short reads mean nothing special (short reads are not treated as error conditions) -<li>a return of zero with the by-thread errno set to nonzero indicates a read error -</ul> -<p> - -<h2>Seek function</h2> - -The seek-like function provided in the <tt>seek_func</tt> field is -used to request non-sequential data access by libvorbisidec, moving -the access cursor to the requested position.<p> - -libvorbisidec expects the following behavior: -<ul> -<li>The seek function must always return -1 (failure) if the given -data abstraction is not seekable. It may choose to always return -1 -if the application desires libvorbisidec to treat the Vorbis data -strictly as a stream (which makes for a less expensive open -operation).<p> - -<li>If the seek function initially indicates seekability, it must -always succeed upon being given a valid seek request.<p> - -<li>The seek function must implement all of SEEK_SET, SEEK_CUR and -SEEK_END. The implementation of SEEK_END should set the access cursor -one past the last byte of accessible data, as would stdio -<tt>fseek()</tt><p> -</ul> - -<h2>Close function</h2> - -The close function should deallocate any access state used by the -passed in instance of the data access abstraction and invalidate the -instance handle. The close function is assumed to succeed.<p> - -One common use of callbacks and the close function is to change the -behavior of libvorbisidec with respect to file closure for applications -that <em>must</em> <tt>fclose</tt> data files themselves. By passing -the normal stdio calls as callback functions, but passing a -<tt>close_func</tt> that does nothing, an application may call <a -href="ov_clear.html">ov_clear()</a> and then <tt>fclose()</tt> the -file originally passed to libvorbisidec. - -<h2>Tell function</h2> - -The tell function is intended to mimic the -behavior of <tt>ftell()</tt> and must return the byte position of the -next data byte that would be read. If the data access cursor is at -the end of the 'file' (pointing to one past the last byte of data, as -it would be after calling <tt>fseek(file,SEEK_END,0)</tt>), the tell -function must return the data position (and thus the total file size), -not an error.<p> - -The tell function need not be provided if the data IO abstraction is -not seekable.<p. - -<br><br> -<hr noshade> -<table border=0 width=100%> -<tr valign=top> -<td><p class=tiny>copyright © 2002 Xiph.org</p></td> -<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td> -</tr><tr> -<td><p class=tiny>Tremor documentation</p></td> -<td align=right><p class=tiny>Tremor version 1.0 - 20020403</p></td> -</tr> -</table> - -</body> - -</html> |