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Chris@41: Secret Rabbit Code (aka libsamplerate)
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Chris@41: <META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)">
Chris@41: <META NAME="Version" CONTENT="libsamplerate-0.1.8">
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Chris@41: <A HREF="index.html">Home</A><BR>
Chris@41: <BR>
Chris@41: <A HREF="api_simple.html">Simple API</A><BR>
Chris@41: <A HREF="api_full.html">Full API</A><BR>
Chris@41: <A HREF="api_callback.html">Callback API</A><BR>
Chris@41: <A HREF="api_misc.html">Miscellaneous</A><BR>
Chris@41: <A HREF="api_misc.html#ErrorReporting">Error Handling</A><BR>
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Chris@41: <DIV CLASS="block">
Chris@41: Author :<BR>Erik de Castro Lopo
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Chris@41: <H1><B>Simple API</B></H1>
Chris@41:
Chris@41: <P>
Chris@41: <B>Important Note:</B>
Chris@41: The simple API is not designed to work on small chunks of a larger piece of
Chris@41: audio.
Chris@41: If you attempt to use it this way you are doing it wrong and will not get the
Chris@41: results you want.
Chris@41: For processing audio data in chunks you <b>must</b> use the
Chris@41: <a href="api_full.html">full api</a>
Chris@41: or the
Chris@41: <a href="api_callback.html">callback based api</a>.
Chris@41: </P>
Chris@41:
Chris@41: <br/><br/>
Chris@41:
Chris@41: <P>
Chris@41: The simple API consists of a single function :
Chris@41: </P>
Chris@41: <PRE>
Chris@41: int src_simple (SRC_DATA *data, int converter_type, int channels) ;
Chris@41: </PRE>
Chris@41: <P>
Chris@41: The use of this function rather than the more fully featured API requires the caller
Chris@41: to know the total length of the input data before hand and that all input and output
Chris@41: data can be held in the system's memory at once.
Chris@41: It also assumes that there is a single constant ratio between input and output sample
Chris@41: rates.
Chris@41: <!--
Chris@41: If these conditions cannot be met, the full featured API should be used instead.
Chris@41: In addition, this documentation is complemented by this
Chris@41: <A HREF="ex_simple.html">example code</A>. -->
Chris@41: </P>
Chris@41:
Chris@41: <P>
Chris@41: Dealing with the easy stuff first, the <B>converter_type</B> parameter should be
Chris@41: one of the values defined in <B>samplerate.h</B> and documented
Chris@41: <A HREF="api_misc.html#Converters">here</A> while the <b>channels</b> parameter
Chris@41: specifies the number of interleaved channels that the sample rate converter
Chris@41: is being asked to process (number of input channels and output channels is always
Chris@41: equal).
Chris@41: There is no hard upper limit on the number of channels; it is limited purely
Chris@41: by the amount of memory available.
Chris@41: </P>
Chris@41:
Chris@41:
Chris@41: <P>
Chris@41: The first parameter to <B>src_simple</B> is a pointer to an <B>SRC_DATA</B> struct
Chris@41: (more info <A HREF="api_misc.html#SRC_DATA">here</A>) defined as follows:
Chris@41: </P>
Chris@41: <PRE>
Chris@41: typedef struct
Chris@41: { float *data_in, *data_out ;
Chris@41:
Chris@41: long input_frames, output_frames ;
Chris@41: long input_frames_used, output_frames_gen ;
Chris@41:
Chris@41: int end_of_input ;
Chris@41:
Chris@41: double src_ratio ;
Chris@41: } SRC_DATA ;
Chris@41: </PRE>
Chris@41: <P>
Chris@41: The fields of this struct which must be filled in by the caller are:
Chris@41: </P>
Chris@41: <PRE>
Chris@41: data_in : A pointer to the input data samples.
Chris@41: input_frames : The number of frames of data pointed to by data_in.
Chris@41: data_out : A pointer to the output data samples.
Chris@41: output_frames : Maximum number of frames pointer to by data_out.
Chris@41: src_ratio : Equal to output_sample_rate / input_sample_rate.
Chris@41: </PRE>
Chris@41: <P>
Chris@41: When the <B>src_simple</B> function returns <B>output_frames_gen</B> will be
Chris@41: set to the number of output frames generated and <B>input_frames_used</B> will
Chris@41: be set to the number of input frames used to generate the provided number of
Chris@41: output frames.
Chris@41: </P>
Chris@41: <P>
Chris@41: The <B>src_simple</B> function returns a non-zero value when an error occurs.
Chris@41: See <A HREF="api_misc.html#ErrorReporting">here</A> for how to convert the error value into
Chris@41: a text string.
Chris@41: </P>
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