Add 5.1 plus stereo-downmix to mov_channel_layout array.

libavformat/isom.c

@@ -442,6 +442,7 @@ static const MovChannelLayout mov_channel_layout[] = {
     { AV_CH_LAYOUT_5POINT1,                      (121<<16) | 6}, //< kCAFChannelLayoutTag_MPEG_5_1_A
     { AV_CH_LAYOUT_7POINT1,                      (128<<16) | 8}, //< kCAFChannelLayoutTag_MPEG_7_1_C
     { AV_CH_LAYOUT_7POINT1_WIDE,                 (126<<16) | 8}, //< kCAFChannelLayoutTag_MPEG_7_1_A
+    { AV_CH_LAYOUT_5POINT1_BACK|AV_CH_LAYOUT_STEREO_DOWNMIX, (130<<16) | 8}, //< kCAFChannelLayoutTag_SMPTE_DTV
     { AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,   (133<<16) | 3}, //< kCAFChannelLayoutTag_DVD_4
     { AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,      (134<<16) | 4}, //< kCAFChannelLayoutTag_DVD_5
     { AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,     (135<<16) | 4}, //< kCAFChannelLayoutTag_DVD_6