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BWF.P vs BWF.M


dfisk

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I know most of the active participators here know the difference between broadcast wave polyphonic files and broadcast wave monophonic files, but part of my new gig is customer education, and I still get asked all the time about the difference between these two. One day, when I was taking my son to archery practice, I tossed him my phone and said "I'm going to shoot a video, ask me about BWF.P vs. BMW.M", and so we did. This is the non-fancy uber low budget result. I mainly did this so when people ask I can just give them this link. Not only is it about the differences between the two types, but why you might use one over the other. 

 

 

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10 hours ago, mikewest said:

When they need to move a take in post, poly allows them to move all the tracks at once!

mike

can't believe I didn't think to say that. I may do a follow up video on situations where you would want one over the other and actually get into specifics like this. 

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Maybe I missed it but you may want to discuss what type of jobs people would do when choosing poly over mono files. I personally have never gotten a request for mono files but my track counts never go over 12, on average I usually run 4-8 tracks. I do may types of jobs, narrative, doc reality type series commercial and etc.

 

 

Sent from my iPhone using Tapatalk

 

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Poly files are certainly more editor-friendly in normal production situations - only one file per take. Most of my work, however, is very large track count (64 or 128 tracks) and sometimes takes of 90 mins length in concert filming, and in that case Poly BWAVs have a few problems. Firstly, it's still considered wise to limit file sized to 4GB maximum, and on a 64 track recorder like a Sound Devices 970, that means the recorder will automatically split your take into a new file every 7 minutes or so. These seamlessly re-join, but freak out post people who are not used to it.  Secondly, the available apps that might be used to extract/split out specific tracks - so you can give a mix track only to the picture editor, for example, only work up to 32 tracks (including Wave Agent - even though Sound Devices make one of the three available 64 channel recorders) . You can dump a 64 Poly BWAV into ProTools and it will split the tracks out, but that isn't quick and simple enough for end-of-day location use really. I don't know what would happen if an assistant editor tried importing a 64-track BWAV into an Avid or FCP. Thirdly, unless your recorder pads out tracks that aren't record-armed, each Poly BWAV take could have a different number of included tracks, and dropping them into Pro Tools can be a little more thought-intensive for an edit assistant as regards getting all the material on the right tracks. For normal 8-16 track film shoots though, Poly's are nowadays more accepted and less susceptible to post losing tracks.

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I did very briefly touch on why one would use Poly or Mono, but didn't get deep into the weeds on it as the length was getting a little long, and I really just wanted to focus on the difference between the two. That being said, it is probably a good idea for me to do a follow up on why one would use Mono over Poly, or vice versa. 

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On 5/12/2017 at 10:41 PM, nickreich said:

You can dump a 64 Poly BWAV into ProTools

ProTools added Poly Wav file support in version 10. Before that you need to use an external app to break them out.

ProTools native has a 32 channel input limit which I believe means 64 channel poly files are not supported - you need ProTools HD or HDX for >32 channels.

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ProTools added Poly Wav file support in version 10. Before that you need to use an external app to break them out.

Do you mean poly wavs with a high channel count? Because I could always add Polys to ProTools, but you'd need to use the import audio path. I think drag and drop was not supported, but an external app was not needed

 

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10 hours ago, Constantin said:


I meant pre PT10. Sorry, I wasn't clear

Yes, the difference being pre PT10, you ended up with the split-out mono files in the working directory.  From PT10, it could use the file directly.   No difference to the PT operator, but would probably have affected what files you end up with when you export the project for Media Composer etc.

(Actually, wouldn't poly files in PT10+ prevent you from dragging and slipping individual tracks if you wanted to correct for mic distances?

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