[vlc-devel] First draft for a Daisy (2.02) playlist support in VLC

[Mathieu SCHROETER]

Hello,

I'm working on a library and a VLC module in order to handle
the Daisy 2.02 specification "playlist" (maybe other in the future)
and to have the ability to read these files with VLC.

  Note that this work is in progress, there are still problems
  and the Daisy 2.02 specification [1] is not fully and correctly
  implemented.
  This library [2] is a first draft.. but it works just enough
  in order to write a first module for VLC. And it is not the
  question here..
  (this work is fully inspired of an other project (libdaisy) [3].
   Daisy 2.02 samples are available on the official website [4]).


In a few words, the Daisy specification is useful for the audio books.
A book is separated by "chapter" and by paragraph. A chapter is
an audio file (MP3, WAV, ..). And a paragraph is a part in this file
(start-time to stop-time). The idea is to seek from a paragraph to
the next, or from a chapter to the next.


With my try for a VLC module, I've some problems. I load the
chapters like a playlist. But in this case, each file (each
chapter) is seen like a "normal" file. I don't know how it can
be possible to provide the seeking by paragraph.

Then I've tried with one entry in the VLC playlist for each
paragraph. In other words, the same file exists several
times and I set the :start-time and :stop-time options for
the paragraph. It works, but between two paragraphs, the same
MP3 file is reloaded then this way is bad. And the ability to
jump from a chapter to the next/prev chapter is lost.

The patch (draft) is available as attachment.


How to provide the seeking by paragraph with a submodule of
demux/playlist ? Maybe it can be done with the Control() function
of the submodule ? My knowledges of the VLC internals is very,
very limited.

An idea can be to have two new buttons in the interface.

     [|<<][<<][stop][>>][>>|]
       ^    ^        ^    ^
       |    |        |    |
p.ch. -'    |  n.pa -'    |
p.pa  ------'  n.ch ------'

p.ch. and n.ch. should be the prev and next file in the playlist
(as now).
p.pa. and n.pa. a seeking where the value of the start-time comes
from the daisy submodule. And I don't know how to do that.


PS: the Daisy 2.02 specification is only for PCM, MP2/3 and ADPCM2.
    If I use VLC for this work is because I will (must) use this
    specification for audio books in webstreaming (rtsp for example),
    then VLC is the best choice.


Thanks for any help..

Regards,
--
Mathieu SCHROETER

[1] http://www.daisy.org/z3986/specifications/daisy_202.html
[2] http://www.geexbox.org/~schroeterm/daisy/libduck-0.0.1-20100318-0838.tar.bz2
[3] http://developer.skolelinux.no/info/studentgrupper/2006-hig-daisyplayer/
[4] http://www.daisy.org/sample-content#t9
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