Gets next frame from file
Frame is represented by the following mapping.
It contains from parsed frame headers and frame
data itself.
([ "bitrate": int
"copyright": int(0..1),
"data": frame_data,
"emphasis": emphasis,
"extension":
"channels":0,
"id":1,
"layer":3,
"original": int(0..1),
"padding": int(0..1),
"private": int(0..1),
"sampling": int
])