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

[Baptiste Coudurier]

Hi Michael,

Michael Niedermayer wrote:
> On Wed, Jun 11, 2008 at 09:13:20PM -0700, Baptiste Coudurier wrote:
>> Michael Niedermayer wrote:
> [...]
>>> MJ2 specifies it should be the channel count
>> My copy just says like 14496-12, aka ChannelCount is either 1 or 2.
>> 
> 
>>> Just compare this to the wording of the base ISO format spec, the
>>>  intent is very clearly to have specs about the format to be 
>>> compatible.
>>> 
>> Yes, but derivatives fail miserably to be intercompatible,
>> unfortunately.
> 
> See below
> 
> [...]
> 
>> We changed it because someone complained that 3gp files were not 
>> compliant.
> 
> Well, after a little searching i found "[Ffmpeg-devel] [PATCH] non
> conformance to 3GP format (3GP TS 26.244 v 6.5.0 2006/06) 2nd try" 
> where Francois Draperi submitted a patch correcting some conformance 
> issues, _BUT_ this patch did not change channelcount. You submitted a
> patch in a reply that did. So let me ask you what kind of non
> compliance where you trying to fix?

Reserved_2 not being set to 2.

> [...]
> 
>> I've did much work already to create compliant files, really Im
>> tired.
> 
> I can understand this but its not moving us closer to a solution.

Clearly it is.

> [...]
> 
> Above _cleary_ says that 3gp does NOT use the channelcount template
> field. Thus 3gp does not ask for any specific value in this field
> differing from the iso base!

IT DOES !!!!!!!!!!

READ SPECS DAMN IT THEY MANDATES VALUE OF 2 FOR 'Reserved_2' field.

> 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 !

> [...]
> 
> Thus they not only may be compatible they MUST be compatible with the
>  ISO base format. Also thats something i already said, our ftyp is
> not correct, "isom" being mandatory not optional.
> 

No, our ftyp is correct, sorry.

Please end this discussion. I am right here.

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