{channel_name_1}: list<item: {data_type_1}>
  child 0, item: {data_type_1}
  -- field metadata --
  rate: '{sample_rate_1}'
...
{channel_name_N}: list<item: {data_type_N}>
  child 0, item: {data_type_N}
  -- field metadata --
  rate: '{sample_rate_N}'
