Add doxygen documentation to libresample.h while it's still fresh on my mind

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@96018 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/libresample/include/libresample.h

@@ -11,6 +11,12 @@
 
 **********************************************************************/
 
+/*!
+ * \file
+ * \brief libresample API
+ * \author Dominic Mazzoni
+ */
+
 #ifndef LIBRESAMPLE_INCLUDED
 #define LIBRESAMPLE_INCLUDED
 
@@ -18,14 +24,74 @@
 extern "C" {
 #endif	/* __cplusplus */
 
+/*!
+ * \brief Create a resampler
+ *
+ * \arg highQuality Set this argument to non-zero to enable higher quality
+ *      resampling.  
+ * \arg minFactor This is the minimum resampling factor that will be used for
+ *      this resampler.  The resampling factor is calculated in the following
+ *      way: ( from sample rate / to sample rate ).
+ * \arg maxFactor This is the maximum resampling factor that will be used for
+ *      this resampler.
+ *
+ * Use this function to create a new resampler that will maintain state
+ * information about the stream of audio being resampled.
+ *
+ * \return A handle to a new resampler
+ */
 void *resample_open(int      highQuality,
                     double   minFactor,
                     double   maxFactor);
 
+/*!
+ * \brief Duplicate a resampler
+ *
+ * \arg handle the resampler to duplicate
+ *
+ * \return A new handle to a resampler, initialized with the same parameters
+ * used to create the original resampler.
+ */
 void *resample_dup(const void *handle);
 
+/*!
+ * \brief Get filter width for resampler
+ * 
+ * \arg handle the resampler
+ *
+ * \return the filter width.
+ */
 int resample_get_filter_width(const void *handle);
 
+/*!
+ * \brief Resample a chunk of audio
+ *
+ * \arg handle the resampler
+ * \arg factor the resampling factor.  This factor should be calculated as
+ *      ( from sample rate / to sample rate ).  So, for converting from 8 kHz
+ *      to 16 kHz, this value would be 2.0.
+ * \arg inBuffer the input buffer for audio to resample.
+ * \arg inBufferLen the number of samples in the input buffer
+ * \arg lastFlag Set this argument to non-zero if the data in the input buffer
+ *      is known to be the end of a stream.  This would be used if you're
+ *      resampling a file, for example.
+ * \arg inBufferUsed This is an output parameter that indicates how many
+ *      samples were consumed from the input buffer.  Generally, this function
+ *      is called in a loop until you know that the entire input buffer has
+ *      been consumed, as it may take multiple calls to complete.
+ * \arg outBuffer This is the output buffer.  This function will write the
+ *      resampled audio into this buffer.
+ * \arg outBufferLen This parameter specifies how many samples there is room
+ *      for in the output buffer.
+ *
+ * This is the main function used for resampling audio.  It should be called
+ * in a loop until all of the data from the input buffer is consumed, or the
+ * output buffer has been filled.
+ *
+ * \return the number of samples written to the output buffer.  If the return
+ *         value is equal to the value provided in the outBufferLen parameter,
+ *         then the output buffer has been filled.
+ */
 int resample_process(void   *handle,
                      double  factor,
                      float  *inBuffer,
@@ -35,6 +101,16 @@ int resample_process(void   *handle,
                      float  *outBuffer,
                      int     outBufferLen);
 
+/*!
+ * \brief Close a resampler
+ *
+ * \arg handle the resampler to close
+ * 
+ * Use this function to release a handle to a resampler that was created using
+ * either resample_open() or resample_dup().
+ *
+ * \return nothing.
+ */
 void resample_close(void *handle);
 
 #ifdef __cplusplus