[FFmpeg-devel] [PATCH] mp4 and ipod metadata

Baptiste Coudurier baptiste.coudurier
Thu Jun 12 20:35:18 CEST 2008

Michael Niedermayer wrote:
> On Thu, Jun 12, 2008 at 10:13:49AM -0700, Baptiste Coudurier wrote:
>> Hi Michael,
>> Michael Niedermayer wrote:
> [...]
>>> Additionally 3gpp says: ----------------------- The file-type brands
>>> defined in this specification are used to label 3GP files belonging
>>> to Release 6 and conforming to one or more profiles. 3GP files may
>>> also conform to earlier Releases or even to other file formats, such
>>> as MP4, which is also derived from the ISO base media file format
>>> [7]. Table 5.1 contains a non-exhaustive list of examples with 3GP
>>> files for various purposes. All 3GP files of Release 5 
>> AFAIK We are using Release 4 !
> release 4 is from 2000/2001
> I really think we should try to be conformant to a recent version of it!
> Especially if one considers that the mp4 and iso base formats arent
> that old themselfs.
> Iam a little puzzled why you refuse to accept the more recent versions.
> Versions that clarify that iso base compatibility and thus a valid
> channel count is mandatory.

What about old devices ? Should we drop old features like psp atoms
because new firmwares work without it ? No.

> Besides id like to repeat that you ignored my objections to the change
> of the channel count to a fixed 2.
> So I request that this change is reverted, unless you can show that it
> has to be 2 for some demuxer hardware of software.

All software I know put 2 here (including gpac which is a very strong

MPEG-4 says template field has to be used:
"In MPEG-4 both visual and aural composition are done using the BIFS
system.  Therefore structures marked as ?template? in the ISO Base Media
Format which pertain to composition, including fields such as matrices,
layers, graphics modes (and their opcolors), volumes, and balance
values, from the MovieHeaderBox and TrackHeaderBox, are all set to their
default values in the file format.
These fields do not define visual or audio composition in MPEG-4; in
MPEG-4, the BIFS system defines the composition."

Are you stubborn or ?

3gp specs mandates value 2 for this field, like I proved many many times.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
Smartjog USA Inc.                                http://www.smartjog.com
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA

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