Vorbis dev - Oct 2004 - libwrit sync questions

Hi list,

I plan to write a tool that incorporates a sequence of three bytes at specific
timeoffsets in an ogg vorbis file. The bitstrings encode commands for a Kodak
slide projector, which upon playback of the file should be sent to the serial
port where the projector receives it. Playing the audio file should effectively
run a slideshow where all the music comes from the audio part, and the commands
for the projector come from some other encoding in the ogg file.

For that pupose the libwrit caught my attention, as it seems to be able to place
song lyrics in audio files. First of all, what is your opinion on the
workability of this. Upon playback, is the bitstring still going to be more or
less in sync with the audio output? Or is there to much buffering going on? Can
I place the bistrings with packet precision?

Also, I am not sure how useable the libwrit is yet. Perhaps there are better
approaches (e.i. a new bitstream, with pretend audio packets; illegal
("corrupted") audiopackets in a normal audio bistream, that still get
passed to
userland; perhaps getting synchronisation through some completely different
means). Any thoughts an pointers appreciated,

best regards,
Fabian Wauthier

Hi Fabian,

you should use a CMML track with libannodex -- these have been pretty
thoroughly tested in real applications and support full
internationalization and correct Ogg synchronization.

http://www.annodex.net/ for more info.

Conrad.

On Mon, Oct 11, 2004 at 01:25:21PM +0100, Fabian Wauthier
wrote:
> Hi list,
> 
> I plan to write a tool that incorporates a sequence of three bytes at
specific
> timeoffsets in an ogg vorbis file. The bitstrings encode commands for a
Kodak
> slide projector, which upon playback of the file should be sent to the
serial
> port where the projector receives it. Playing the audio file should
effectively
> run a slideshow where all the music comes from the audio part, and the
commands
> for the projector come from some other encoding in the ogg file.
> 
> For that pupose the libwrit caught my attention, as it seems to be able to
place
> song lyrics in audio files. First of all, what is your opinion on the
> workability of this. Upon playback, is the bitstring still going to be more
or
> less in sync with the audio output? Or is there to much buffering going on?
Can
> I place the bistrings with packet precision?
> 
> Also, I am not sure how useable the libwrit is yet. Perhaps there are
better
> approaches (e.i. a new bitstream, with pretend audio packets; illegal
> ("corrupted") audiopackets in a normal audio bistream, that still
get passed to
> userland; perhaps getting synchronisation through some completely different
> means). Any thoughts an pointers appreciated,
> 
> best regards,
> Fabian Wauthier
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