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[Gabriel Pinheiro]

Dear Folks,

I'll be in germany, recording the audio of a show during the Football World Cup.  It will also be recorded in HDV.  Everything there runs at 50Hz.
My problem is that all the post production will be in Brazil, where we run at 60Hz.  The video guys will have to do a conversion from 50Hz/25 fps to 60Hz/29.97fps.  
I have no idea how the audio will behavior.  We will not be running in sync, no timecode, no house sync, no blackburst.  My first thought was that, as there will be no video sync, my audio will stay at 48khz, no matter the change from 50hz to 60hz, but I'm not really sure...
Has anyone been in a situation like that?

Best regards,

Gabriel Pinheiro

[blueintheface]

Your audio clock is not dervied from the mains - it will stay at 48K

[Jon Hodgson]

Why no timecode sync?

Firstly ignoring the frame rate changes your audio stands a chance of ending up out of sync with the video, because no unit runs at exactly the specified rate. How much of a problem this is depends on the tolerances of the various units in question (both at filming and in postpro) and how long each take is.

The other question is whether the guys will really be converting to 29.97fps, or converting to 30fps and just playing back marginally slowly. I don't know what people do these days, but I'd check if I were you.

[Gabriel Pinheiro]

Thanks for the help.
There will be no sync because they will be shooting with HDV cameras, small ones, no tc input or sync in, I guess.
Blueintheface, that was my first thought, my audio will be 48khz, and that does not dpend on power cicles.
Dear Jon, the video crew will shot at 50i with the cameras because it wiil be a concert, so the lights would flick if they shoot at 60i.  I really don't know how the process will go beyond that, they just told me they'll have to do a conversion from 25 frames/50hz to 30 frames, 60hz.  That's all I know, unfortunatelly...

Thanks again for the input.

Best regards,

Gabriel

[Jon Hodgson]

Gabriel Pinheiro wrote on Sat, 10 June 2006 04:06

Thanks for the help. There will be no sync because they will be shooting with HDV cameras, small ones, no tc input or sync in, I guess. Blueintheface, that was my first thought, my audio will be 48khz, and that does not dpend on power cicles. Dear Jon, the video crew will shot at 50i with the cameras because it wiil be a concert, so the lights would flick if they shoot at 60i.  I really don't know how the process will go beyond that, they just told me they'll have to do a conversion from 25 frames/50hz to 30 frames, 60hz.  That's all I know, unfortunatelly... Thanks again for the input. Best regards, Gabriel

Well if they're converting to 30 frames, but will actually be playing back at 29.97, you'll have to adjust your playback rate to compensate. If you look at audio clocking units aimed at the video/film industry you'll see that they have a number of sample rates which are intended for the various pull ups and downs you can get when converting from one format to another.