> I then tried doing it with the command-line tool mp4tags and the same
> thing happened.

> In either case, if the file already had some tags, it works.

> Am I doing something wrong or is this a limitation of the library?

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> That is interesting, and no should not be a limitation of the library.

> I guess it is related to the opening of the file using MP4Modify() and  
> there not being enough existing room for the metadata.

> Try instrumenting the code somewhat to see what is going on, in  
> particular mp4v2/src/itmf/Tags.cpp.

> How are you generating these MP4s in the first place?

> Cheers, Ed.

> On 29/07/2009, at 10:09 AM, donmesserli wrote:

> > I've tried writing a program and using MP4TagsStore(), etc. to add
> > iTunes Meta Tags to a file that doesn't have any.  The tags aren't
> > written to the file.

> > I then tried doing it with the command-line tool mp4tags and the same
> > thing happened.

> > In either case, if the file already had some tags, it works.

> > Am I doing something wrong or is this a limitation of the library?

>  smime.p7s
> 2KViewDownload

> Don

> On Jul 28, 6:19 pm, Edward Groenendaal <ed...@myreflection.org> wrote:

> > Hi,

> > That is interesting, and no should not be a limitation of the library.

> > I guess it is related to the opening of the file using MP4Modify() and  
> > there not being enough existing room for the metadata.

> > Try instrumenting the code somewhat to see what is going on, in  
> > particular mp4v2/src/itmf/Tags.cpp.

> > How are you generating these MP4s in the first place?

> > Cheers, Ed.

> > On 29/07/2009, at 10:09 AM, donmesserli wrote:

> > > I've tried writing a program and using MP4TagsStore(), etc. to add
> > > iTunes Meta Tags to a file that doesn't have any.  The tags aren't
> > > written to the file.

> > > I then tried doing it with the command-line tool mp4tags and the same
> > > thing happened.

> > > In either case, if the file already had some tags, it works.

> > > Am I doing something wrong or is this a limitation of the library?

> >  smime.p7s
> > 2KViewDownload

> MP4TagsStore() calls
> Tags::c_store calls
> Tags::storeString calls
> Tags::store calls
> genericAddItem which includes the code...

> MP4Atom* ilst = file.FindAtom( "moov.udta.meta.ilst" );
>    if( !ilst )
>        return false;

> Since the atom can't be found, it returns and does nothing.
> The atom isn't there because there isn't any metadata in the file yet.

> It appears that I might be able to work at a lower level (i.e.
> MP4File) and create the atom. Ideas?

> Don

> On Jul 29, 10:20 am, donmesserli <donmesse...@gmail.com> wrote:
>> The files were converted from alac to aac using afconvert.  I will do
>> some debugging.  Am I right that the tags aren't actually written to
>> the file until MP4Close() is called?

>> Don

>> On Jul 28, 6:19 pm, Edward Groenendaal <ed...@myreflection.org>  
>> wrote:

>>> Hi,

>>> That is interesting, and no should not be a limitation of the  
>>> library.

>>> I guess it is related to the opening of the file using MP4Modify()  
>>> and
>>> there not being enough existing room for the metadata.

>>> Try instrumenting the code somewhat to see what is going on, in
>>> particular mp4v2/src/itmf/Tags.cpp.

>>> How are you generating these MP4s in the first place?

>>> Cheers, Ed.

>>> On 29/07/2009, at 10:09 AM, donmesserli wrote:

>>>> I've tried writing a program and using MP4TagsStore(), etc. to add
>>>> iTunes Meta Tags to a file that doesn't have any.  The tags aren't
>>>> written to the file.

>>>> I then tried doing it with the command-line tool mp4tags and the  
>>>> same
>>>> thing happened.

>>>> In either case, if the file already had some tags, it works.

>>>> Am I doing something wrong or is this a limitation of the library?

>>>  smime.p7s
>>> 2KViewDownload

> Well done on finding it.

> I think we should change the code in the lib to create the atom if it
> isn't found.

> I've only got iPhone ineternet access at the moment so can't work on
> this for a little while.

> Cheers Ed.

> On 1/08/2009, at 4:01, donmesserli <donmesse...@gmail.com> wrote:

> > I've found out where it is happening...

> > MP4TagsStore() calls
> > Tags::c_store calls
> > Tags::storeString calls
> > Tags::store calls
> > genericAddItem which includes the code...

> > MP4Atom* ilst = file.FindAtom( "moov.udta.meta.ilst" );
> >    if( !ilst )
> >        return false;

> > Since the atom can't be found, it returns and does nothing.
> > The atom isn't there because there isn't any metadata in the file yet.

> > It appears that I might be able to work at a lower level (i.e.
> > MP4File) and create the atom. Ideas?

> > Don

> > On Jul 29, 10:20 am, donmesserli <donmesse...@gmail.com> wrote:
> >> The files were converted from alac to aac using afconvert.  I will do
> >> some debugging.  Am I right that the tags aren't actually written to
> >> the file until MP4Close() is called?

> >> Don

> >> On Jul 28, 6:19 pm, Edward Groenendaal <ed...@myreflection.org>
> >> wrote:

> >>> Hi,

> >>> That is interesting, and no should not be a limitation of the
> >>> library.

> >>> I guess it is related to the opening of the file using MP4Modify()
> >>> and
> >>> there not being enough existing room for the metadata.

> >>> Try instrumenting the code somewhat to see what is going on, in
> >>> particular mp4v2/src/itmf/Tags.cpp.

> >>> How are you generating these MP4s in the first place?

> >>> Cheers, Ed.

> >>> On 29/07/2009, at 10:09 AM, donmesserli wrote:

> >>>> I've tried writing a program and using MP4TagsStore(), etc. to add
> >>>> iTunes Meta Tags to a file that doesn't have any.  The tags aren't
> >>>> written to the file.

> >>>> I then tried doing it with the command-line tool mp4tags and the
> >>>> same
> >>>> thing happened.

> >>>> In either case, if the file already had some tags, it works.

> >>>> Am I doing something wrong or is this a limitation of the library?

> >>>  smime.p7s
> >>> 2KViewDownload

> I've found out where it is happening...

> MP4TagsStore() calls
> Tags::c_store calls
> Tags::storeString calls
> Tags::store calls
> genericAddItem which includes the code...

> MP4Atom* ilst = file.FindAtom( "moov.udta.meta.ilst" );
>    if( !ilst )
>        return false;

> Since the atom can't be found, it returns and does nothing.
> The atom isn't there because there isn't any metadata in the file yet.

> It appears that I might be able to work at a lower level (i.e.
> MP4File) and create the atom. Ideas?

> Don

> I think we should change the code in the lib to create the atom if it  
> isn't found.

> I've only got iPhone ineternet access at the moment so can't work on  
> this for a little while.