[FFmpeg-devel] [PATCH] avformat/mov: parse 3gpp titl from media or track udta

[Jan Ekström]

On Wed, Jul 21, 2021 at 8:30 PM Jan Ekström <jeebjp at gmail.com> wrote:
>
> On Wed, Jul 21, 2021 at 8:28 PM Jan Ekström <jeebjp at gmail.com> wrote:
> >
> > Seems to be:
> > * Utilized by Handbrake for track titling
> > * Actually defined as "title for the media"
> >
> > Definition from 3GPP TS 26.244 follows:
> >
> > Field               Type                Details                             Value
> > BoxHeader.Size      Unsigned int(32)                                        BOX_SIZE
> > BoxHeader.Type      Unsigned int(32)                                        'titl'
> > BoxHeader.Version   Unsigned int(8)                                         0
> > BoxHeader.Flags     Bit(24)                                                 0
> > Pad                 Bit(1)                                                  0
> > Language            Unsigned int(5)[3]  Packed ISO-639-2/T language code
> > Title               String              Text of title
> >
> > Semantics:
> >
> > Language: declares the language code for the following text. See
> > ISO 639-2/T for the set of three character codes. Each character
> > is packed as the difference between its ASCII value and 0x60.
> >
> > The code is confined to being three lower-case letters, so these
> > values are strictly positive.
> >
> > Title: null-terminated string in either UTF-8 or UTF-16 characters,
> > giving a title information. If UTF-16 is used, the string shall
> > start with the BYTE ORDER MARK (0xFEFF).
> > ---
>
> A sample for this sort of metadata can be seen with
> https://0x0.st/-zjq.m4v , which was posted at
> https://github.com/mpv-player/mpv/issues/8488 .
>
> The sample contains both "name" and "titl" boxes:
> [udta: User Data Box]
>     position = 3991500
>     size = 71
>     [name]
>         position = 3991508
>         size = 28
>     [titl]
>         position = 3991536
>         size = 35
>
> ...out of which if I read QTFF documentation correctly "name" should
> not be utilized for user-facing naming, and "titl" is actually a
> user-facing metadata box. Thus I implemented the latter.
>
> Jan

Ping.

Includes a link to a testable file, and the specification of the box
is in the commit message :)

Jan