Latest post Mon, Nov 2 2009 8:00 AM by Job ter Burg. 6 replies.
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  • Fri, Oct 23 2009 3:20 AM

    sample rates in 24p pal

    I am working on a film shot on Genesis at 24 fps on a MC v3.05. 

    I imported my BWF files into the 24p project with the method 2 (video rate 100%+). My audio settings were 48k and bit depth 24 bit.

    in the import options I selected 

    CONVERT SOURCE SAMPLE RATE TO PROJECT SAMPLE RATE

    CONVERT SOURCE SAMPLE RATES WITH AUDIO PULLUP OR PULLDOWN TO PROJECT SAMPLE RATE ON IMPORT

    CONVERT SOURCE SAMPLE RATE BIT DEPTH TO PROJECT SAMPLE BIT DEPTH ON IMPORT

    I sent a test OMF off to the post sound and they complained the sample rate was 46k and they had to convert it to 48k.

    This was confirmed in the avid bins.

    so i turned off the setting

    CONVERT SOURCE SAMPLE RATES WITH AUDIO PULLUP OR PULLDOWN TO PROJECT SAMPLE RATE ON IMPORT

    and audio was imported at 48k and this satisfied the sound post.

    I then went to playout to digibeta and it said

    NOT ALL AUDIO SEGMENTS ARE AT THE PROJECT SAMPLE RATE. PLEASE CONVERT BEFORE PERFORMING A DIGITAL CUT

    The only way to playout was to convert all the audio to 46k.

    What would be the ideal workflow?

    Thanks : )

  • Fri, Oct 23 2009 8:13 AM In reply to

    Re: sample rates in 24p pal

    Laurie Hughes:

    I am working on a film shot on Genesis at 24 fps on a MC v3.05. 

    I imported my BWF files into the 24p project with the method 2 (video rate 100%+).

    Well, sorry to bring it up, but that's where you went pretty wrong. Method 2 does not equal Video Rate. Method 1 does. Method 2 equals "Film Rate". If you actually were set to Video Rate, and select all those options, then yes, you probably have been sample rate converting the source files.

    Method 1 / Video Rate assumes picture and sound being brought in together at telecine speed (Video Rate). Audio and video will both be slowed down to 24.00fps, which implies a sample rate conversion for the sound, making it not suitable for audio post through OMF/AAF, it will require post conforming.

    Method 2 / Film Rate assumes picture and sound being brought in separately, picture at telecine speed, audio at its original true speed (48000Hz, Film Rate). There is no sample rate conversion being applied.

    Not sure how you have managed to keep everything in sync with those settings. Not sure how to solve it (other than post conforming), but as long as your project is set to "Video Rate", the sample clock will be set differently in order to accomplish sound pulldown. What happens if you set your project to "Film Rate", you deselect ALL of the conversion options, and batch import the original BWFs?

    Symphony Classic Nitris 4.0.2 on 2x 2.33 quad core XW8400/8GB Vista Biz 64bit | MC 4.0.2 on 2x dual core 2.66 XW8400/7GB Vista Biz 64bit | Mojo SDI | Unity... [view my complete system specs]
  • Sat, Oct 24 2009 3:54 AM In reply to

    Re: sample rates in 24p pal

    Job ter Burg:

    I am working on a film shot on Genesis at 24 fps on a MC v3.05. 

    I imported my BWF files into the 24p project with the method 2 (video rate 100%+).

    My bad, although the MC help does list film rate above video rate in the help, I should have looked closer to see the detail that video rate = method 1.

    Job ter Burg:

    Not sure how you have managed to keep everything in sync with those settings. Not sure how to solve it (other than post conforming), but as long as your project is set to "Video Rate", the sample clock will be set differently in order to accomplish sound pulldown.

    So far I have been importing my audio in VIDEO RATE and i turned off the setting

    CONVERT SOURCE SAMPLE RATES WITH AUDIO PULLUP OR PULLDOWN TO PROJECT SAMPLE RATE ON IMPORT

    and audio was imported at 48k. everything has been in sync, 48k and autosync between a b cameras has been fine.

    Job ter Burg:

    What happens if you set your project to "Film Rate", you deselect ALL of the conversion options, and batch import the original BWFs?

    I have done 1 test so far and it seems to work. The clips stayed in sync and I could do a digital cut. I will get back to you when I have done a few more clips and made certain though.

    Thanks for your help.

     

     

     

  • Sat, Oct 24 2009 7:56 AM In reply to

    Re: sample rates in 24p pal

    Laurie Hughes:
    The clips stayed in sync and I could do a digital cut.
    Please do double check if the sample rate for the clips is listed as being correct (48000).

    Symphony Classic Nitris 4.0.2 on 2x 2.33 quad core XW8400/8GB Vista Biz 64bit | MC 4.0.2 on 2x dual core 2.66 XW8400/7GB Vista Biz 64bit | Mojo SDI | Unity... [view my complete system specs]
  • Mon, Oct 26 2009 12:07 AM In reply to

    Re: sample rates in 24p pal

    yes they are at 48k

  • Mon, Nov 2 2009 2:00 AM In reply to

    Re: sample rates in 24p pal

    FYI

    I was able to make a digital cut by simply switching over to film rate. as I mentioned by telling it not to pull up to match the project sample rate when in video rate I was able to get the audio in at 48k instead of 46k. If I tried to do a digital cut when using video rate I was ask to convert it all to 46k. when I switched it over to film rate it would play out fine.

    thanks again for your help

  • Mon, Nov 2 2009 8:00 AM In reply to

    Re: sample rates in 24p pal

    That does make sense, though. When you toggle between Film Rate and Video Rate, you are basically changing the system's sample clock frequency.

    Symphony Classic Nitris 4.0.2 on 2x 2.33 quad core XW8400/8GB Vista Biz 64bit | MC 4.0.2 on 2x dual core 2.66 XW8400/7GB Vista Biz 64bit | Mojo SDI | Unity... [view my complete system specs]
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