add API function to perform volume adjustment on a frame of SLINEAR data

documentation cleanup

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@6874 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/frame.c b/frame.c
index 5d9ddab118bb32a6e70e8f651af3ee0e59c0b64e..7b4fa4ddf53f215c6713e5da7046d86b6b4ec52e 100755 (executable)
--- a/frame.c
+++ b/frame.c
@@ -1252,3 +1252,22 @@ int ast_codec_get_len(int format, int samples)
 
        return len;
 }
+
+int ast_frame_adjust_volume(struct ast_frame *f, int adjustment)
+{
+       int count;
+       short *fdata = f->data;
+
+       if ((f->frametype != AST_FRAME_VOICE) || (f->subclass != AST_FORMAT_SLINEAR))
+               return -1;
+
+       for (count = 0; count < f->samples; count++) {
+               if (adjustment > 0) {
+                       fdata[count] *= abs(adjustment);
+               } else if (adjustment < 0) {
+                       fdata[count] /= abs(adjustment);
+               }
+       }
+
+       return 0;
+}

diff --git a/include/asterisk/frame.h b/include/asterisk/frame.h
index 48a2bbebb0bf7806de83c8f8476232fb3e093aca..c17e2eecbebe2a0dd33e1019e89f642b6d4745c1 100755 (executable)
--- a/include/asterisk/frame.h
+++ b/include/asterisk/frame.h
@@ -49,7 +49,7 @@ struct ast_frame {
        int samples;                            
        /*! Was the data malloc'd?  i.e. should we free it when we discard the frame? */
        int mallocd;                            
-       /*! How far into "data" the data really starts */
+       /*! How many bytes exist _before_ "data" that can be used if needed */
        int offset;                             
        /*! Optional source of frame for debugging */
        const char *src;                                
@@ -64,8 +64,8 @@ struct ast_frame {
 };
 
 #define AST_FRIENDLY_OFFSET    64              /*! It's polite for a a new frame to
-                                                                               have this number of bytes for additional
-                                                                                       headers.  */
+                                                 have this number of bytes for additional
+                                                 headers.  */
 #define AST_MIN_OFFSET                 32              /*! Make sure we keep at least this much handy */
 
 /*! Need the header be free'd? */
@@ -419,6 +419,14 @@ static inline int ast_codec_interp_len(int format)
        return (format == AST_FORMAT_ILBC) ? 30 : 20;
 }
 
+/*!
+  \brief Adjusts the volume of the audio samples contained in a frame.
+  \param f The frame containing the samples (must be AST_FRAME_VOICE and AST_FORMAT_SLINEAR)
+  \param adjustment The number of dB to adjust up or down.
+  \return 0 for success, non-zero for an error
+ */
+int ast_frame_adjust_volume(struct ast_frame *f, int adjustment);
+
 #if defined(__cplusplus) || defined(c_plusplus)
 }
 #endif