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doc/api.html : Add documentation for virtual I/O functionality.

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Erik de Castro Lopo 2011-03-15 20:55:20 +11:00
parent c6e84b99bd
commit 02bb6e5a8d
3 changed files with 87 additions and 1 deletions
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3
.bzrignore
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@ -11,13 +11,16 @@
*.loT
*.oct
*.oga
*.ogg
*.paf
*.rifx
*.sd2
*.sds
*.svx
*.w64
*.wav
*.wavex
*.8svx
.deps
.git*
.libs

3
ChangeLog
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@ -9,6 +9,9 @@
* doc/libsndfile.css.in
Add tweaks for h4 element.
* doc/api.html
Add documentation for virtual I/O functionality. Thanks to Uli Franke.
2011-03-08 Erik de Castro Lopo <erikd AT mega-nerd DOT com>
* configure.ac

82
doc/api.html
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@ -64,7 +64,7 @@ The functions of libsndfile are defined as follows:
SNDFILE* <A HREF="#open">sf_open</A> (const char *path, int mode, SF_INFO *sfinfo) ;
SNDFILE* <A HREF="#open_fd">sf_open_fd</A> (int fd, int mode, SF_INFO *sfinfo, int close_desc) ;
SNDFILE* <A HREF="#open_virtual">sf_open_virtual</A> (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data) ;
int <A HREF="#check">sf_format_check</A> (const SF_INFO *info) ;
sf_count_t <A HREF="#seek">sf_seek</A> (SNDFILE *sndfile, sf_count_t frames, int whence) ;
@ -306,6 +306,86 @@ that audio file.
On fail, the sf_open_fd function returns a NULL pointer.
</P>
<A NAME="open_virtual"></A>
<h3><b>Virtual File Open Function</b></h3>
<pre>
SNDFILE* sf_open_virtual (SF_VIRTUAL_IO *sfvirtual, int mode, SF_INFO *sfinfo, void *user_data) ;
</pre>
<p>
Opens a soundfile from a virtual file I/O context which is provided
by the caller. This is usually used to interface libsndfile to a stream or buffer
based system. Apart from the sfvirtual and the user_data parameters this function behaves
like <a href="#open">sf_open</a>.
</p>
<pre>
typedef struct
{ sf_vio_get_filelen get_filelen ;
sf_vio_seek seek ;
sf_vio_read read ;
sf_vio_write write ;
sf_vio_tell tell ;
} SF_VIRTUAL_IO ;
</pre>
<p>
Libsndfile calls the callbacks provided by the SF_VIRTUAL_IO structure when opening, reading
and writing to the virtual file context. The user_data pointer is a user defined context which
will be available in the callbacks.
</p>
<pre>
typedef sf_count_t (*sf_vio_get_filelen) (void *user_data) ;
typedef sf_count_t (*sf_vio_seek) (sf_count_t offset, int whence, void *user_data) ;
typedef sf_count_t (*sf_vio_read) (void *ptr, sf_count_t count, void *user_data) ;
typedef sf_count_t (*sf_vio_write) (const void *ptr, sf_count_t count, void *user_data) ;
typedef sf_count_t (*sf_vio_tell) (void *user_data) ;
</pre>
<h4>sf_vio_get_filelen</h4>
<pre>
typedef sf_count_t (*sf_vio_get_filelen) (void *user_data) ;
</pre>
<p>
The virtual file contex must return the length of the virtual file in bytes.<br>
</p>
<h4>sf_vio_seek</h4>
<pre>
typedef sf_count_t (*sf_vio_seek) (sf_count_t offset, int whence, void *user_data) ;
</pre>
<p>
The virtual file context must seek to offset using the seek mode provided by whence which is one of<br>
</p>
<pre>
SEEK_CUR
SEEK_SET
SEEK_END
</pre>
<p>
The return value must contain the new offset in the file.
</p>
<h4>sf_vio_read</h4>
<pre>
typedef sf_count_t (*sf_vio_read) (void *ptr, sf_count_t count, void *user_data) ;
</pre>
<p>
The virtual file context must copy ("read") "count" bytes into the
buffer provided by ptr and return the count of actually copied bytes.
</p>
<h4>sf_vio_write</h4>
<pre>
typedef sf_count_t (*sf_vio_write) (const void *ptr, sf_count_t count, void *user_data) ;
</pre>
<p>
The virtual file context must process "count" bytes stored in the
buffer passed with ptr and return the count of actually processed bytes.<br>
</p>
<h4>sf_vio_tell</h4>
<pre>
typedef sf_count_t (*sf_vio_tell) (void *user_data) ;
</pre>
<p>
Return the current position of the virtual file context.<br>
</p>
<A NAME="check"></A>
<BR><H2><B>Format Check Function</B></H2>