Ticket #1028:
 - Updated codecs docs, more detail info about codec settings.



git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@3083 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/pjmedia/include/pjmedia-codec/g7221.h b/pjmedia/include/pjmedia-codec/g7221.h
index ba66c22..9785b44 100644
--- a/pjmedia/include/pjmedia-codec/g7221.h
+++ b/pjmedia/include/pjmedia-codec/g7221.h
@@ -28,41 +28,71 @@
 #include <pjmedia-codec/types.h>
 
 /**
- * @defgroup PJMED_G7221_CODEC G722.1 Codec
+ * @defgroup PJMED_G7221_CODEC G.722.1 Codec (Siren7/Siren14)
  * @ingroup PJMEDIA_CODEC_CODECS
- * @brief Implementation of G722.1 codec
+ * @brief Implementation of G.722.1 codec
  * @{
  *
- * <b>G722.1 licensed from Polycom®</b>
- * <b>G722.1 Annex C licensed from Polycom®</b>
+ * <b>G.722.1 licensed from Polycom®</b><br />
+ * <b>G.722.1 Annex C licensed from Polycom®</b>
  *
- * This section describes functions to register and register G722.1 codec
+ * This section describes functions to initialize and register G.722.1 codec
  * factory to the codec manager. After the codec factory has been registered,
  * application can use @ref PJMEDIA_CODEC API to manipulate the codec.
  *
  * PJMEDIA G722.1 codec implementation is based on ITU-T Recommendation 
  * G.722.1 (05/2005) C fixed point implementation including its Annex C.
  *
- * G722.1 is a low complexity codec that supports for 7kHz and 14kHz bandwidth
- * audio signals working at bitrates ranging from 16kbps to 48kbps. It may be
+ * G.722.1 is a low complexity codec that supports 7kHz and 14kHz audio 
+ * bandwidth working at bitrates ranging from 16kbps to 48kbps. It may be
  * used with speech or music inputs.
  *
- * The codec implementation supports for standard and non-standard bitrates.
- * By default, the standard bitrates are enabled upon initialization, i.e.:
- * - 24kbps and 32kbps for audio bandwidth 7 kHz (16kHz sampling rate),
- * - 24kbps, 32kbps, and 48kbps for audio bandwidth 14 kHz (32kHz sampling 
- *   rate).
- * The usage of non-standard bitrates must follow this requirements:
- * - for sampling rate 16kHz: 16000 to 32000 bps, it must be a multiple of 400
- * - for sampling rate 32kHz: 24000 to 48000 bps, it must be a multiple of 400
- * Note that currently it is only up to two non-standard modes can be enabled
- * at one time.
+ *
+ * \section codec_setting Codec Settings
+ *
+ * \subsection general_setting General Settings
+ *
+ * General codec settings for this codec such as VAD and PLC can be 
+ * manipulated through the <tt>setting</tt> field in #pjmedia_codec_param. 
+ * Please see the documentation of #pjmedia_codec_param for more info.
+ *
+ * \subsection specific_setting Codec Specific Settings
+ *
+ * The following settings are applicable for this codec.
+ *
+ * \subsubsection bitrate Bitrate
+ *
+ * The codec implementation supports standard and non-standard bitrates.
+ * Use #pjmedia_codec_g7221_set_mode() to enable or disable the bitrates.
+ *
+ * By default, only standard bitrates are enabled upon initialization:
+ * - for 7kHz audio bandwidth (16kHz sampling rate): 24kbps and 32kbps,
+ * - for 14kHz audio bandwidth (32kHz sampling rate): 24kbps, 32kbps, and
+ *   48kbps.
+ *
+ * The usage of non-standard bitrates must follow these requirements:
+ * - for 7kHz audio bandwidth (16kHz sampling rate): 16000 to 32000 bps, 
+ *   multiplication of 400
+ * - for 14kHz audio bandwidth (32kHz sampling rate): 24000 to 48000 bps,
+ *   multiplication of 400
+ *
+ * \note
+ * Currently only up to two non-standard modes can be enabled.
+ *
+ * \remark
+ * There is a flaw in the codec manager as currently it could not
+ * differentiate G.722.1 codecs by bitrates, hence invoking 
+ * #pjmedia_codec_mgr_set_default_param() may only affect a G.722.1 codec
+ * with the highest priority (or first index found in codec enumeration 
+ * when they have same priority) and invoking
+ * #pjmedia_codec_mgr_set_codec_priority() will set priority of all G.722.1
+ * codecs with sampling rate as specified.
  */
 
 PJ_BEGIN_DECL
 
 /**
- * Initialize and register G722.1 codec factory to pjmedia endpoint.
+ * Initialize and register G.722.1 codec factory to pjmedia endpoint.
  *
  * @param endpt	    The pjmedia endpoint.
  *
@@ -72,13 +102,13 @@
 
 
 /**
- * Enable and disable G722.1 mode. By default, the standard modes are 
+ * Enable and disable G.722.1 mode. By default, the standard modes are 
  * enabled upon initialization, i.e.:
  * - sampling rate 16kHz, bitrate 24kbps and 32kbps.
  * - sampling rate 32kHz, bitrate 24kbps, 32kbps, and 48kbps.
  * This function can also be used for enabling non-standard modes.
- * Note that currently it is only up to two non-standard modes can be 
- * enabled at one time.
+ * Note that currently only up to two non-standard modes can be enabled
+ * at one time.
  *
  * @param sample_rate	PCM sampling rate, in Hz, valid values are only 
  *			16000 and 32000.
@@ -110,7 +140,7 @@
 
 
 /**
- * Unregister G722.1 codecs factory from pjmedia endpoint.
+ * Unregister G.722.1 codecs factory from pjmedia endpoint.
  *
  * @return	    PJ_SUCCESS on success.
  */