Add libsamplerate for resampling decoder output

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+---
+layout: default
+---
+
+# Simple API
+
+**Important Note:** 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
+**must** use the [full api](api_full.md) or the [callback based api](api_callback.md).
+
+The simple API consists of a single function:
+
+```c
+int src_simple (SRC_DATA *data, int converter_type, int channels) ;
+```
+
+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.
+
+Dealing with the easy stuff first, the **converter_type** parameter should be
+one of the values defined in **samplerate.h** and documented [here](api_misc.md#converters)
+while the **channels** 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.
+
+The first parameter to **src_simple** is a pointer to an **SRC_DATA** struct
+(more info [here](api_misc.md#src_data)) defined as follows:
+
+```c
+typedef struct
+{   const float  *data_in;
+    float *data_out ;
+
+    long   input_frames, output_frames ;
+    long   input_frames_used, output_frames_gen ;
+
+    int    end_of_input ;
+
+    double src_ratio ;
+} SRC_DATA ;
+```
+
+The fields of this struct which must be filled in by the caller are:
+
+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.
+
+When the **src_simple** function returns **output_frames_gen** will be set to
+the number of output frames generated and **input_frames_used** will be set to
+the number of input frames used to generate the provided number of output
+frames.
+
+The **src_simple** function returns a non-zero value when an error occurs. See
+[here](api_misc.md#error-reporting) for how to convert the error value into a
+text string.