+ audios: Indexes in hb_title_t's audios list, starting from 0.
+ -1 indicates the end of the list
+ audio_mixdowns: The mixdown to be used for each audio track in audios[] */
+
+/* define some masks, used to extract the various information from the HB_AMIXDOWN_XXXX values */
+#define HB_AMIXDOWN_DCA_FORMAT_MASK 0x00FFF000
+#define HB_AMIXDOWN_A52_FORMAT_MASK 0x00000FF0
+#define HB_AMIXDOWN_DISCRETE_CHANNEL_COUNT_MASK 0x0000000F
+
+/* define the HB_AMIXDOWN_XXXX values */
+
+#define HB_AMIXDOWN_MONO 0x01000001
+// DCA_FORMAT of DCA_MONO = 0 = 0x000
+// A52_FORMAT of A52_MONO = 1 = 0x01
+// discrete channel count of 1
+
+#define HB_AMIXDOWN_STEREO 0x02002022
+// DCA_FORMAT of DCA_STEREO = 2 = 0x002
+// A52_FORMAT of A52_STEREO = 2 = 0x02
+// discrete channel count of 2
+
+#define HB_AMIXDOWN_DOLBY 0x042070A2
+// DCA_FORMAT of DCA_3F1R | DCA_OUT_DPLI = 519 = 0x207
+// A52_FORMAT of A52_DOLBY = 10 = 0x0A
+// discrete channel count of 2
+
+#define HB_AMIXDOWN_DOLBYPLII 0x084094A2
+// DCA_FORMAT of DCA_3F2R | DCA_OUT_DPLII = 1033 = 0x409
+// A52_FORMAT of A52_DOLBY | A52_USE_DPLII = 74 = 0x4A
+// discrete channel count of 2
+
+#define HB_AMIXDOWN_6CH 0x10089176
+// DCA_FORMAT of DCA_3F2R | DCA_LFE = 137 = 0x089
+// A52_FORMAT of A52_3F2R | A52_LFE = 23 = 0x17
+// discrete channel count of 6
+
+/* define some macros to extract the various information from the HB_AMIXDOWN_XXXX values */
+#define HB_AMIXDOWN_GET_DCA_FORMAT( a ) ( ( a & HB_AMIXDOWN_DCA_FORMAT_MASK ) >> 12 )
+#define HB_AMIXDOWN_GET_A52_FORMAT( a ) ( ( a & HB_AMIXDOWN_A52_FORMAT_MASK ) >> 4 )
+#define HB_AMIXDOWN_GET_DISCRETE_CHANNEL_COUNT( a ) ( ( a & HB_AMIXDOWN_DISCRETE_CHANNEL_COUNT_MASK ) )
+