AndrewFG;665859 Wrote: > Unfortunately I think there is still a part of this story missing... > > Apple .M4A music files consist of a raw data music stream, that is > wrapped inside an ISO MPEG4 file container. > > MPEG4 is an open ISO standard that defines a nestable structure of > "boxes", where each such box has a name, and a predefined data payload. > The ISO standard specifies some of the standard box names and their > respective payloads. But the standard is extensible and allows vendors > to add their own box definitions, and define their respective payloads. > This works fine, because if a particular client does not understand the > contents of a particular box type, it can ignore it and jump over to > the next box. > > One such standard MPEG4 box is the music stream box; it may contain > MP3, MP4, AAC, ALAC or proprietary raw stream data. Therefore it is of > course excellent news that Apple has open sourced the ALAC format, > because it increases the number of public domain raw data stream > payload formats that the standard MPEG4 music stream box can carry. > > BUT, Apple still still uses other (proprietary) boxes to carry the > track meta-data (i.e. the tags). These Apple proprietary metadata boxes > obviously fit within the overall ISO format, and their names are known, > and their payload structures have been reverse engineered. (So for > example the SBS Scanner knows how to parse the tags). HOWEVER, so far > as I know, these meta data tags have NOT been open sourced by Apple, so > they could change the payload structures at whim, and thus "break" any > third party applications that rely on them... > > => Dear Apple, please also open source your meta data boxes!!
Ok this means that this "open" support is basically useless we have to rely on reverse engineered stuff anyway . or *shrug* some one will use this knowledge and use alac with some nonstandard tagging scheme :-/ -- Mnyb -------------------------------------------------------------------- Main hifi: Touch + CIA PS +MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub. Bedroom/Office: Boom Kitchen: Touch + powered Fostex PM0.4 Misc use: Radio (with battery) iPad 64gB wifi +3g with iPengHD & SqueezePad (in storage SB3, reciever ) ------------------------------------------------------------------------ Mnyb's Profile: http://forums.slimdevices.com/member.php?userid=4143 View this thread: http://forums.slimdevices.com/showthread.php?t=91185 _______________________________________________ discuss mailing list discuss@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/discuss
