Trying to solve bug 240409

[Abhinandan Ramprasath]

Hi,

After going through the source of TagLib, I can confidently say it
currently does not support chapters in MP4 or M4A files. The information u
can get out of the library includes title, album, artist, comment, year,
track, genre. This information is directly available in the header of the
MP4 file. The problem with decoding the chapter markers is that it is not
stored in the header ( apple's patented it apparently ) or rather,
scattered around in the file. I am still hoping for some positive reply
from the TagLib Developers ( they haven't replied yet ).

Will let you know of any developments.


On Thu, Feb 21, 2013 at 8:57 PM, Abhinandan Ramprasath <abhiin1947 at gmail.com
> wrote:

>
>
> On Thu, Feb 21, 2013 at 4:17 AM, Matěj Laitl <matej at laitl.cz> wrote:
>
>> On 19. 2. 2013 Abhinandan Ramprasath wrote:
>> > This is what I've got so far,
>>
>> Nice research!
>>
>> > 1) mp4v2-2.0.0 supports chapters in mp4 files(mentioned on comment 2).
>> The
>> > format for chapter storage is specified between lines 2321 and 2375
>> under
>> > src/mp4file.cpp (
>> >
>> http://code.google.com/p/mp4v2/downloads/detail?name=mp4v2-2.0.0.tar.bz2) .
>>
>> Okay.
>>
>> > 2) comment 2 in https://bugs.kde.org/show_bug.cgi?id=240409 mentions
>> that
>> > the dependency was removed. Is it safe for me to add it back?
>>
>> We'd prefer not to, certainly not as a mandatory dependency.
>>
>> > 3) I cross checked the format of chapter storage with a simple cpp
>> program
>> > I wrote and got the titles of all chapters as output. But that was just
>> > using a regex and I'm not too sure that would be accepted as a solution.
>>
>> RegExes are used all over Amarok, so if this is not a moving target (e.g.
>> if
>> the strings you match don't change with library versions), it should be
>> fine,
>> but see below.
>>
> I'm not sure if it is a moving target. Will read about it and get back.
>
>>
>> > 4) An Issue was filed for TagLib
>> > https://github.com/taglib/taglib/issues/81 asking
>> > to expand support for chapters in mp3 files, which sadly, hasn't been
>> > solved yet. Unfortunately, I wasn't able to find anything similar for
>> mp4.
>>
>> You fan file one, then! ;) Even better would be creating a pull request
>> for
>> TagLib that would add support for reading chapters (ideally both from mp3
>> and
>> mp4 files). Given that mp4v2 is under MPL 1.1 and TagLib is under MPL 1.1
>> +
>> LGPL 2.1, it may be possible to copy & adapt code from mp4v2 to TagLib
>> directly, but please consult this first with TagLib developers [1]. (if
>> both
>> mp4v2 and TagLib where updated to the newest MPL 2.0, it would be
>> definitely
>> possible)
>>
>
> Ya, trying to get the feature working on Taglib was the next thing I was
> going to do. I will try to find more information about it and get back.
>
>>
>> Let's defer the decision how to represent this in Amarok until underlying
>> libraries are ready, I must say that the idea to use MultiTrack may end
>> up to
>> be the good way, but please let us think about this more.
>>
> I think Multitrack is how QuickTime does it( or I have a really old
> version ) and it looks pretty good.
>
> P.S sorry for submitting the patch, I was almost done with it when I read
> the email
>
>> [1] https://mail.kde.org/mailman/listinfo/taglib-devel
>>
>>         Matěj
>>
>
>
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