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HDCam, DolbyE, and 23.98

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Joseph Owens
HDCam, DolbyE, and 23.98
on Apr 29, 2012 at 8:22:58 pm

Seems like its not so straight forward.
I understand all that Non-Audio/Continuous segmented data stream, and even played around with External Sync alternatives.... but.... (having done a lot of successful 59.94 masters)....

I have two output systems, one Blackmagic Decklink Extreme and one AJA Kona3.

I'm noticing that BMD don't really have a specific 23.98PsF setting, while AJA do. Now I can play a Dolby E stream E-E through my SRW-550 in HDCam mode, monitoring the AES output through the Neyrinck Dolby E decoder. All well and good, but as soon as you attempt to assemble the project to tape --- nope. Not out of the Blackmagic. No way, no how. None shall pass.

AJA offers 'sF' as a distinct format, and I'm finding that an assemble to tape from the Kona3, although in record-mode causes thousands of CRC errors at least actually passes the data, but sounds very choppy. The chop goes away in playback, and I get zero CRC errors, so chalk up another successful Master pass.

Yeesh.

jPo

You mean "Old Ben"? Ben Kenobi?


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Juan Salvo
Re: HDCam, DolbyE, and 23.98
on Apr 29, 2012 at 8:31:36 pm

Good question. ;)

I think your problem here is audio resampling. If the audio signal is resampled on input/output (as I know it is on BMD) you loose the integrity of the DolbyE data. This is why you have to put your HDCAM decks in dolby mode, or turn off resampling on D5 decks to work with DolbyE. Unfortunately the BMD cards don't have a similar setting.

With regards to the 24p vs PsF. What BMD allows is electing to use a proper P signal as a checkbox in the Sys Pref panel "use P instead of PsF" (or something similar). But the default is PsF, as it should be. And in the NLE there is no distinction between P & PsF as all the file media is in fact actually P.

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Joseph Owens
Re: HDCam, DolbyE, and 23.98
on Apr 30, 2012 at 4:51:57 pm

[Juan Salvo] "I think your problem here is audio resampling."

I agree, but its more like "total restructuring" -- what I found puzzling is that the Dolby E stream from the BMD Decklink is allowed to pass through the deck E->E and the neyrinck decoder recognizes it -- all good. However, in confidence playback during record, it just registers as noise, so yes, the encoding structure is destroyed. After a few hours of trying to force an external sync feed to work, it occurred to me that the Sony deck might be doing its own segmenting, trying to deal with a non-segmented input. I was feeding an AJA Gen10 Trilevel to both the Decklink and the SRW and it ONLY settled down when I selected 1080P23.98 in the binary dip switches. However, it was still not recordable. When I finally gave up on the BMD and moved the project to the AJA Kona, I didn't even need the external sync box. With no changes in the Sony VTR Setup, the Kona3-HDSDI output (although choppy in confidence monitoring) was accepted and the decoder saw the stream as what it should be, metadata and all. Playback after the edit was finished resulted in a clean QA.

But, you know the drill, another 4 hours of my life wasted on a 25 minute dub.

jPo

You mean "Old Ben"? Ben Kenobi?


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Frank Gothmann
Re: HDCam, DolbyE, and 23.98
on May 26, 2012 at 11:39:40 am

Interesting. Not sure what the issue is but I have successfully laid Dolby E to SR tape (SRW 5800) with a BMD Decklink 3D. Final tape passed QA at the broadcaster.

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Joseph Owens
Re: HDCam, DolbyE, and 23.98
on Jun 15, 2012 at 4:09:13 pm

[Frank Gothmann] "I have successfully laid Dolby E to SR tape (SRW 5800) with a BMD Decklink 3D. Final tape passed QA at the broadcaster."

Me, too. 2997 not a problem if that was what you were delivering to broadcaster. The issue here is 23.98.

The Dolby E encode is also, obviously burst-encoded for 2398 but a real PITA.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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