Hey guys. For my upcoming short film im planning on having the film based around a character who all we know about him is his voice. Almost exactly like phonebooth. Now when my other character is talking to him on the phone..i want to add in the audio after in post. How would i know how much time to leave my actor so i can insert the voice correctly ? Any ideas on this ?

I'm in a similar situation. I plan to record all the voice over work a week or so before the video shoot. That way I will know approximately how long I need each take to be as I finialize my shot list. Of course I will take some coverage shots and the fine details will be worked out in post.

That sounds like a good idea, just record it and give the actor a small ear bud on the side not facing the camera on which they can hear the audio. Maybe make sure to pad your shooting with a few extra shots of miscellaneous extra footage, and then if you run into a problem...you can let the voice over run over the miscellaneous shot before you cut back to the person on the phones audio/shot.

I've done a few phone call shots and I always just call the person on the phone on set (someone off set talking to them) and have the conversation in real time. It does two things, one, makes the character more natural (which is especially important if they aren't very experienced), and two, gives you an opportunity to have a more engaged telephone conversation because they are really talking on the phone. The inflections will be more believable and the vocabulary will flow better. You can set it up to record both sides of the audio at the same time (at the different locations) and either use the secondary audio or use it for a guide during VO in post.

One thing to watch for with this! Carefully monitor the audio! If you are going to have a MALE do the voice over, have a MALE make the phone call to the set. Some of this audio can be picked up by microphones and nothing makes you feel like a bigger ass than having one shot with a MALE voice going over the phone and the next shot hears receiving what sounds like a distant FEMALE voice!... not that I know from experience... I've been told... ok, but I learned from that mistake!

I would also shoot it from enough different angles that you can do some extra cuts if needed to tighten the video to the final audio later without jumps. And the point about the voice heard thru the phone is good. It will make it more realistic to hear that, rather than perfect "studio sound".

I seem to remember seeing something like this in the commentary for "I Spy" (Owen Wilson, Eddie Murphy). There's a scene where they're communicating over a two-way video link. They actually shot both actors at the same time, so they really were interacting in realtime (rather than having one react to a recorded video of the other).

Depending on the way your "voice" actor is heard, a real phone conversation may work best. There are ways to actually tap the audio from the phone and pipe it into a recorder if you want that authentic phone sound. Otherwise, you may be able to have someone off-camera whisper or mouth the words, depending on the nature of the shot and the sensitivity of your mic.

I've never tried this for video, so I may be way off on this. Post again and let us know how it goes.