lavu/audioconvert: add a second low frequency channel.

Can be used by DTS-HD, TrueHD and E-AC-3, among others.
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:     2011-04-18
 
 API changes, most recent first:
 
+2012-09-12 - xxxxxxx - lavu 51.41.0 - audioconvert.h
+  Added AV_CH_LOW_FREQUENCY_2 channel mask value.
+
 2012-09-04 - xxxxxxx - lavu 51.40.0 - opt.h
   Reordered the fields in default_val in AVOption, changed which
   default_val field is used for which AVOptionType.

libavutil/audioconvert.c

@@ -53,6 +53,7 @@ static const char * const channel_names[] = {
     [32] = "WR",        /* wide right */
     [33] = "SDL",       /* surround direct left */
     [34] = "SDR",       /* surround direct right */
+    [35] = "LFE2",      /* low frequency 2 */
 };
 
 static const char *get_channel_name(int channel_id)

libavutil/audioconvert.h

@@ -62,6 +62,7 @@
 #define AV_CH_WIDE_RIGHT             0x0000000100000000ULL
 #define AV_CH_SURROUND_DIRECT_LEFT   0x0000000200000000ULL
 #define AV_CH_SURROUND_DIRECT_RIGHT  0x0000000400000000ULL
+#define AV_CH_LOW_FREQUENCY_2        0x0000000800000000ULL
 
 /** Channel mask value used for AVCodecContext.request_channel_layout
     to indicate that the user requests the channel order of the decoder output

libavutil/version.h

@@ -37,7 +37,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 40
+#define LIBAVUTIL_VERSION_MINOR 41
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \