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Secret Rabbit Code (aka libsamplerate)
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<A HREF="index.html">Home</A><BR>
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<A HREF="api_simple.html">Simple API</A><BR>
<A HREF="api_full.html">Full API</A><BR>
<A HREF="api_callback.html">Callback API</A><BR>
<A HREF="api_misc.html">Miscellaneous</A><BR>
<A HREF="api_misc.html#ErrorReporting">Error Handling</A><BR>
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Author :<BR>Erik de Castro Lopo
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<H1><B>Simple API</B></H1>
<P>
<B>Important Note:</B>
The simple API is not designed to work on small chunks of a larger piece of
audio.
If you attempt to use it this way you are doing it wrong and will not get the
results you want.
For processing audio data in chunks you <b>must</b> use the
<a href="api_full.html">full api</a>
or the
<a href="api_callback.html">callback based api</a>.
</P>
<br/><br/>
<P>
The simple API consists of a single function :
</P>
<PRE>
int src_simple (SRC_DATA *data, int converter_type, int channels) ;
</PRE>
<P>
The use of this function rather than the more fully featured API requires the caller
to know the total length of the input data before hand and that all input and output
data can be held in the system's memory at once.
It also assumes that there is a single constant ratio between input and output sample
rates.
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If these conditions cannot be met, the full featured API should be used instead.
In addition, this documentation is complemented by this
<A HREF="ex_simple.html">example code</A>. -->
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<P>
Dealing with the easy stuff first, the <B>converter_type</B> parameter should be
one of the values defined in <B>samplerate.h</B> and documented
<A HREF="api_misc.html#Converters">here</A> while the <b>channels</b> parameter
specifies the number of interleaved channels that the sample rate converter
is being asked to process (number of input channels and output channels is always
equal).
There is no hard upper limit on the number of channels; it is limited purely
by the amount of memory available.
</P>
<P>
The first parameter to <B>src_simple</B> is a pointer to an <B>SRC_DATA</B> struct
(more info <A HREF="api_misc.html#SRC_DATA">here</A>) defined as follows:
</P>
<PRE>
typedef struct
{ float *data_in, *data_out ;
long input_frames, output_frames ;
long input_frames_used, output_frames_gen ;
int end_of_input ;
double src_ratio ;
} SRC_DATA ;
</PRE>
<P>
The fields of this struct which must be filled in by the caller are:
</P>
<PRE>
data_in : A pointer to the input data samples.
input_frames : The number of frames of data pointed to by data_in.
data_out : A pointer to the output data samples.
output_frames : Maximum number of frames pointer to by data_out.
src_ratio : Equal to output_sample_rate / input_sample_rate.
</PRE>
<P>
When the <B>src_simple</B> function returns <B>output_frames_gen</B> will be
set to the number of output frames generated and <B>input_frames_used</B> will
be set to the number of input frames used to generate the provided number of
output frames.
</P>
<P>
The <B>src_simple</B> function returns a non-zero value when an error occurs.
See <A HREF="api_misc.html#ErrorReporting">here</A> for how to convert the error value into
a text string.
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