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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> |
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| Author :<BR>Erik de Castro Lopo |
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| <H1><B>Full API</B></H1> |
| <P> |
| The full API consists of the following functions : |
| </P> |
| <PRE> |
| SRC_STATE* <A HREF="#Init">src_new</A> (int converter_type, int channels, int *error) ; |
| SRC_STATE* <A HREF="#CleanUp">src_delete</A> (SRC_STATE *state) ; |
| |
| int <A HREF="#Process">src_process</A> (SRC_STATE *state, SRC_DATA *data) ; |
| int <A HREF="#Reset">src_reset</A> (SRC_STATE *state) ; |
| int <A HREF="#SetRatio">src_set_ratio</A> (SRC_STATE *state, double new_ratio) ; |
| </PRE> |
| |
| <A NAME="Init"></A> |
| <H3><BR>Initialisation</H3> |
| <PRE> |
| SRC_STATE* src_new (int converter_type, int channels, int *error) ; |
| </PRE> |
| <P> |
| The <B>src_new</B> function returns an anonymous pointer to a sample rate |
| converter object, src_state. |
| If an error occurs the function returns a NULL pointer and fills in the |
| error value pointed to by the <B>error</B> pointer supplied by the caller. |
| The converter must be one of the supplied converter types documented |
| <A HREF="api_misc.html#Converters">here</A>. |
| </P> |
| |
| <A NAME="CleanUp"></A> |
| <H3><BR>Cleanup</H3> |
| <PRE> |
| SRC_STATE* src_delete (SRC_STATE *state) ; |
| </PRE> |
| <P> |
| The <B>src_delete</B> function frees up all memory allocated for the given sample |
| rate converter object and returns a NULL pointer. |
| The caller is responsible for freeing any memory passed to the sample rate converter |
| via the pointer to the <B>SRC_DATA</B> struct. |
| </P> |
| |
| <A NAME="Process"></A> |
| <H3><BR>Process</H3> |
| <PRE> |
| int src_process (SRC_STATE *state, SRC_DATA *data) ; |
| </PRE> |
| <P> |
| The <B>src_process</B> function processes the data provided by the caller |
| in an <B>SRC_DATA</B> struct using the sample rate converter object specified |
| by the <B>SRC_STATE</B> pointer. |
| When operating on streaming data, this function can be called over and over again, |
| with each new call providing new input data and returning new output data. |
| </P> |
| |
| <P> |
| The <B>SRC_DATA</B> struct passed as the second parameter to the <B>src_process</B> |
| function has the following fields: |
| </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. |
| end_of_input : Equal to 0 if more input data is available and 1 |
| otherwise. |
| </PRE> |
| <P> |
| Note that the data_in and data_out arrays may not overlap. If they do, the |
| library will return an error code. |
| </P> |
| <P> |
| When the <B>src_process</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 consumed to generate the provided number of |
| output frames. |
| </P> |
| |
| <P> |
| The <B>src_process</B> function returns non-zero if an error occurs. |
| The non-zero error return value can be decoded into a text string using the function |
| documented <A HREF="api_misc.html#ErrorReporting">here</A>. |
| </P> |
| |
| <A NAME="Reset"></A> |
| <H3><BR>Reset</H3> |
| <PRE> |
| int src_reset (SRC_STATE *state) ; |
| </PRE> |
| <P> |
| The <B>src_reset</B> function resets the internal state of the sample rate |
| converter object to the same state it had immediately after its creation using |
| <B>src_new</B>. |
| This should be called whenever a sample rate converter is to be used on two |
| separate, unrelated pieces of audio. |
| </P> |
| |
| <A NAME="SetRatio"></A> |
| <H3><BR>Set Ratio</H3> |
| <PRE> |
| int src_set_ratio (SRC_STATE *state, double new_ratio) ; |
| </PRE> |
| |
| <p> |
| When using the <B>src_process</B> or <B>src_callback_process</B> APIs and |
| updating the <B>src_ratio</B> field of the <B>SRC_STATE</B> struct, the library |
| will try to smoothly transition between the conversion ratio of the last call |
| and the conversion ratio of the current call. |
| <p/> |
| |
| <P> |
| If the user want to bypass this smooth transition and achieve a step response in |
| the conversion ratio, the <B>src_set_ratio</B> function can be used to set the |
| starting conversion ratio of the next call to <B>src_process</B> or |
| <B>src_callback_process</B>. |
| <p/> |
| |
| <P> |
| This function returns non-zero on error and the error return value can be |
| decoded into a text string using the function documented |
| <A HREF="api_misc.html#ErrorReporting">here</A>.</P> |
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