src/io/source.h: add a note about the different libraries

diff --git a/src/io/source.h b/src/io/source.h
index e47a2a8..bcc0975 100644 (file)
--- a/src/io/source.h
+++ b/src/io/source.h
@@ -25,8 +25,31 @@
 
   Media source to read blocks of consecutive audio samples from file
 
+  Depending on how aubio was compiled, the following file formats will be
+  available.
+
   To write to file, use ::aubio_sink_t.
 
+  \b \p source_avcodec : libav
+
+  aubio can be optionally compiled with [libav](http://libav.org), which can
+  read from a very large number of audio and video formats, including over
+  different network protocols such as HTTP.
+
+  \b \p source_apple_audio : ExtAudioFileRef
+  
+  On Mac and iOS platforms, aubio should be compiled with CoreAudio [Extended
+  Audio File Services]
+  (https://developer.apple.com/library/mac/documentation/musicaudio/CAAudioTooboxRef/_index.html).
+  This provides access to most common audio file formats, including compressed
+  ones.
+
+  \b \p source_sndfile : libsndfile
+
+  Also optional, aubio can be built against
+  [libsndfile](http://www.mega-nerd.com/libsndfile/), which can read [most
+  uncompressed formats](http://www.mega-nerd.com/libsndfile/#Features).
+
   \example io/test-source.c
   \example io/test-source_multi.c