[FFmpeg-devel] metadata updates while playing

[Ronald S. Bultje]

Hi,

RTP/ASF apparently has this interesting thing "medata updates" while
the radio plays. This is used to continuously inform the extremely
interested user on which top-40 artist is currently making your life
miserable^d^d^d.

Anyway, here mux/audio-out sync comes in to play again. How would you
want this to be handled? The data basically comes in a caption channel
(like audio/video, but "application" - similar in many ways to
subtitle except that it's not very useful) and could thus be handled
by a "decoder" to convert to UTF-8 and keep sync. If I go that route,
how would the decoder signal the metadata updates to the application?

Hexdump of a sample packet follows:
00000000   54 00 45 00  58 00 54 00  00 00 49 00  44 00 3D 00  T.E.X.T...I.D.=.
00000010   30 00 26 00  41 00 52 00  54 00 49 00  53 00 54 00  0.&.A.R.T.I.S.T.
00000020   3D 00 42 00  45 00 43 00  4B 00 26 00  54 00 49 00  =.B.E.C.K.&.T.I.
00000030   54 00 4C 00  45 00 3D 00  4C 00 45 00  4F 00 50 00  T.L.E.=.L.E.O.P.
00000040   41 00 52 00  44 00 20 00  53 00 4B 00  49 00 4E 00  A.R.D. .S.K.I.N.
00000050   20 00 50 00  49 00 4C 00  4C 00 20 00  42 00 4F 00   .P.I.L.L. .B.O.
00000060   58 00 20 00  48 00 41 00  26 00 4E 00  41 00 52 00  X. .H.A.&.N.A.R.
00000070   54 00 49 00  53 00 54 00  3D 00 44 00  45 00 43 00  T.I.S.T.=.D.E.C.
00000080   45 00 4D 00  42 00 45 00  52 00 49 00  53 00 54 00  E.M.B.E.R.I.S.T.
00000090   53 00 26 00  4E 00 54 00  49 00 54 00  4C 00 45 00  S.&.N.T.I.T.L.E.
000000A0   3D 00 44 00  41 00 59 00  53 00 20 00  4F 00 46 00  =.D.A.Y.S. .O.F.
000000B0   20 00 45 00  4C 00 41 00  49 00 4E 00  45 00 00 00   .E.L.A.I.N.E...

Ronald