[vlc] drive in theater (synchronization audio-fm / video)

[jm]

Dear vlc users,

I'm part of a local radio in France [1], and we plan to organize a drive in
theater, by broadcasting the audio part of a movie throw our FM broadcasting
system, then by projecting in a screen the movie.
The main question is the synchronization between the audio and video streams:
the antenna will be probably far from the drive in location.
Do you know if vlc is able to synchronize the reading of a movie (video part)
using an audio input coming from an FM receiver (using for example the audio
in of the computer) ? And do you think it's required to synchronize not only
at the beginning of the movie?

Thank you for your answers and ideas.

Cheers

[Doug]

Post by jm
Dear vlc users,
I'm part of a local radio in France [1], and we plan to organize a drive in
theater, by broadcasting the audio part of a movie throw our FM broadcasting
system, then by projecting in a screen the movie.
the antenna will be probably far from the drive in location.
Do you know if vlc is able to synchronize the reading of a movie (video part)
using an audio input coming from an FM receiver (using for example the audio
in of the computer) ? And do you think it's required to synchronize not only
at the beginning of the movie?
Thank you for your answers and ideas.
Cheers

I think if you mean an on-site FM transmitter, you'll be fine, but if you mean you're going to send the audio to a regular
broadcast station several miles (kilometers) away, and then have it broadcast back from there, you'll have a serious
synchronization problem. Even fairly slight non-synchronization of lip movement with pronunciation is quite disconcerting.
The same is true of movies portraying the playing of a musical instrument, especially something like a piano or a drum.

I can't answer about vlc, but the above is what you're dealing with.

--doug

[jm]

Hi

Thank you Doug for your answer

Post by Doug
I think if you mean an on-site FM transmitter, you'll be fine, but if you
mean you're going to send the audio to a regular broadcast station several
miles (kilometers) away, and then have it broadcast back from there, you'll
have a serious synchronization problem.

Yes, you're right, that is the configuration. My idea is to have the regular FM
transmitter as master, and the video streaming driven as a slave using an FM
receiver to synchronize the video with regards to the audio...

[Edit B]

----- Original Message -----
From: "jm" <***@gmail.com>
To: "Mailing list for VLC media player users" <***@videolan.org>
Sent: Saturday, January 10, 2015 9:35 PM
Subject: Re: [vlc] drive in theater (synchronization audio-fm / video)


Hi

Thank you Doug for your answer

Post by Doug
I think if you mean an on-site FM transmitter, you'll be fine, but if you
mean you're going to send the audio to a regular broadcast station several
miles (kilometers) away, and then have it broadcast back from there, you'll
have a serious synchronization problem.

===
I totally disagree.
Concidering a FM signal travels with about the speed of light, there will be
absolutely NO sync problems due to the distance af the broadcasting.
(300.000 km / second. So 30 km will introduce 0.1 millisecond of delay. One
frame film is 42 Msecs.)

If you have a tremendous amount of equipment in the pipeline between input
and arial / antenna, that might introduce a delay.
Now that will be constant, and VLC can compensate for that (it's an easy
menu item)

If you have an internet connection, have a look at VLC's sync play, start
with command line --control netsync --netsync-master etc...
Or, get Syncplay (google syncplay vlc).
Have two copies of the movie (one could be sound only), the network will
keep 'm sync worry free.

hth,
Bouke


===
Yes, you're right, that is the configuration. My idea is to have the regular
FM
transmitter as master, and the video streaming driven as a slave using an FM
receiver to synchronize the video with regards to the audio...
--
jm - http://jmtrivial.info
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