+static const uint64_t thd_channel_order[] = {
+ AV_CH_FRONT_LEFT, AV_CH_FRONT_RIGHT, // LR
+ AV_CH_FRONT_CENTER, // C
+ AV_CH_LOW_FREQUENCY, // LFE
+ AV_CH_SIDE_LEFT, AV_CH_SIDE_RIGHT, // LRs
+ AV_CH_TOP_FRONT_LEFT, AV_CH_TOP_FRONT_RIGHT, // LRvh
+ AV_CH_FRONT_LEFT_OF_CENTER, AV_CH_FRONT_RIGHT_OF_CENTER, // LRc
+ AV_CH_BACK_LEFT, AV_CH_BACK_RIGHT, // LRrs
+ AV_CH_BACK_CENTER, // Cs
+ AV_CH_TOP_CENTER, // Ts
+ AV_CH_SURROUND_DIRECT_LEFT, AV_CH_SURROUND_DIRECT_RIGHT, // LRsd
+ AV_CH_WIDE_LEFT, AV_CH_WIDE_RIGHT, // LRw
+ AV_CH_TOP_FRONT_CENTER, // Cvh
+ AV_CH_LOW_FREQUENCY_2, // LFE2
+};
+
+static uint64_t thd_channel_layout_extract_channel(uint64_t channel_layout,
+ int index)
+{
+ int i;
+
+ if (av_get_channel_layout_nb_channels(channel_layout) <= index)
+ return 0;
+
+ for (i = 0; i < FF_ARRAY_ELEMS(thd_channel_order); i++)
+ if (channel_layout & thd_channel_order[i] && !index--)
+ return thd_channel_order[i];
+ return 0;
+}
+