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Old September 30th, 2005, 09:55 PM   #1
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HD100 supports PCM audio record/playback

As you may know, ProHD allows for the addition of 2 channels of PCM audio. At NAB, I was told by a Sony engineer from Japan, the HD100 have this capability -- although it might not be announced.

Using FCP 5, I have now been able to capture from the FireWire port of the camera, a single PCM audio channel.

We know the HD100 does not downconvert HDV to DV. So when you switch the 1394 switch to DV and set the playback mode to DV -- nothing should come out of the 1394 port.

Yet there is a signal -- one that can be captured as "NTSC DV 48 kHz" WITHOUT video. (Also, with no real device control.)

You see the MPEG-2 "data" on the FCP input monitor while the PCM audio capture occurs.

Why only one channel -- even though I had the on-board mic into input 1 (to ch. 1) and sourced ch. 2 from input 1? There certainly are two HDV channels played back.

One possibility is a flaw in my workflow -- or a problem with FCP.

JVC has now confirmed to me that both channels should have been recorded as PCM audio to tape. So I'll check my tape with another editor.

Anyway, the good thing is that we do have both MPEG and PCM recorded with the HD100!
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Old September 30th, 2005, 10:40 PM   #2
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I thought somebody said the HD100 wasn't going to do the second audio set?

Are you sure when shooting it records both sets of audio?

If this is true then that is one huge bonus over the HDV2 1080i format.
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Old September 30th, 2005, 11:51 PM   #3
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That was the public position. But, now JVC has confirmed that PCM is present in the HD100. But, it will take a modified DV capture software driver to really make use of it.

The software must use DV FW protocol but not look for video, ignore the non DV video signal, and simply capture the PCM audio tracks by which DV audio is carried.

Hopefully, CineForm will soon support this option.

Then you'll edit as you would any "seperate audio" timeline. You'll have to sync via slate -- dropping the MPEG audio.
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Last edited by Steve Mullen; October 1st, 2005 at 04:07 PM.
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Old October 1st, 2005, 06:34 AM   #4
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This is surprising. Do JVC plan to make a public statement about the capability to record PCM?
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Old October 1st, 2005, 04:12 PM   #5
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Quote:
Originally Posted by Werner Wesp
This is surprising. Do JVC plan to make a public statement about the capability to record PCM?
Given the ProHD definition, it really has been public. However, until NLE software is developed -- a fairly trival task (in FCP it would simply be anothe FireWire Control Preset) -- I don't think there will be a JVC announcement.
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Old October 1st, 2005, 04:41 PM   #6
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Quote:
Originally Posted by Werner Wesp
Do JVC plan to make a public statement about the capability to record PCM?
It's in the HD100 operator's manual, which is publicly available.
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Old October 3rd, 2005, 07:03 AM   #7
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I couldn't make that out in the manual (need to read it again, I guess...), but I thought there were several statements (official) that this camcorder wouldn't encode the PCM yet, that that was just supported later on...
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Old October 3rd, 2005, 08:44 AM   #8
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My mistake, it may or may not be in the manual, but it's very clearly stated in the 18-page brochure (which has seen a wider public release than the manual anyway). It's on page 4, near the top, under "4-channel audio capability."
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Old October 3rd, 2005, 11:15 AM   #9
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Quote:
Originally Posted by Chris Hurd
My mistake, it may or may not be in the manual, but it's very clearly stated in the 18-page brochure (which has seen a wider public release than the manual anyway). It's on page 4, near the top, under "4-channel audio capability."
The "ProHD" brochure also confused the hell out of me this summer. Page 4 actually totes the "Advantages of ProHD" not specifically the HD100. Also check out the bottom of page 2 "Future 4 channel audio capability."
It says the track sectors have been reserved for future recording of an additional 2 tracks, but they were careful not to say the the HD100 simultaneously records PCM.

Page 5 is really tittilating where they talk about multi-bit rate capability of "ProHD XE." I assume this refers to the HD7000?

Frankly, I would bet that the HD100 is capable of PCM recording and 720P60 capture/recording at a faster tape speed/higher bit rate, but JVC doesn't want to put all the eggs in one basket until the HD7000 hits market. Maybe they'll release a ProHD XE HD100"A" next summer with those features!
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Old October 3rd, 2005, 12:51 PM   #10
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Quote:
Originally Posted by Chris Hurd
My mistake, it may or may not be in the manual, but it's very clearly stated in the 18-page brochure (which has seen a wider public release than the manual anyway). It's on page 4, near the top, under "4-channel audio capability."
Yes, but that has nothing to do with the HD100. The HD100 is two-channel only. As Tim said, that brochure is very confusing -- it mixes the announced, planned upgrades of ProHD XE in with the existing product. But make no mistake, the HD100 is a two-channel-only product.

JVC explained it to me this way: the HD100 records two channels of MPEG-1 Layer II audio, according to the HDV specifications. That's what you get -- two channels. But, JVC's lower bitrate makes it such that they can handle those two channels within the video-only track on the DV tape. So that leaves the whole audio area unused. And since it's a dual-format camera (HDV and DV), it has the capability to write to the DV tape's audio tracks, so... why not? Apparently the JVC engineers decided to go ahead and write the audio to the DV PCM track as well, simultaneously.

Which explains the weird 1394 switch for "HDV" or "DV" -- that switch seems nearly superfluos, as it doesn't do what you'd expect (downrez). But apparently what the switch does is tell the camera whether to treat the data on tape as if it was HDV or DV. So if the switch is in HDV mode, it reads the HDV data off the tape and outputs it, and that means you get compressed audio. But if you rewind and re-digitize with the switch in the DV position, you'll actually get the uncompressed 16-bit 48khz PCM audio that was recorded simultaneously! Pretty cool, actually. Kind of like recording dual-system sound within the one unit. You'd have to slate it with a clapper to sync it up, but hey -- it's a whole lot better than having no PCM audio at all, definitely a plus for JVC's implementation of HDV.
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Old October 3rd, 2005, 08:25 PM   #11
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Thanks Barry - your explanation seemed somehow clearer. I'm still lost to the real advantage if you don't have separate audio circuits to input to the PCM tracks. You haven't really got a four channel recorder, you have a two x two channel recorder.

I'm completely bemused that JVC decided to output the compressed MPEG audio tracks in HDV if the PCM tracks are there...

The switch simply switches a bunch of circuitry within the camera (as DV and HDV are processed totally differently). Probably something they could have implemented in a simple logic circuit and controlled with the format switch.
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Old October 3rd, 2005, 09:09 PM   #12
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Well, the advantage is that you're not limited to the compressed audio. You also have access to the same audio tracks that have been recorded as uncompressed PCM.

There aren't four tracks, there are two -- but those two tracks are recorded twice. Once in HDV-compliant MPEG-1 Layer II, and the other time in uncompressed PCM. No matter how you slice it, uncompressed is going to beat compressed every which way from Sunday.

So -- why didn't JVC just go with uncompressed and ditch the whole compressed-audio thing? Don't know. But having access to the uncompressed audio can only be viewed as a bonus. Sure it's a little inconvenient (having to capture everything twice) but a) nobody says you have to use it, and b) at least it's there!
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Old October 4th, 2005, 01:47 AM   #13
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I wonder if, with the proper NLE support, it can actually output a 1394 stream with the MPG2 video and the uncompressed audio. It would save the duplication of capturing etc if it could.

I have a feeling Steve hinted at this being possible, but I found his wording a bit cryptic and could easily have been mistaken.
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Old October 4th, 2005, 01:55 AM   #14
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Quote:
Originally Posted by Barry Green
So -- why didn't JVC just go with uncompressed and ditch the whole compressed-audio thing? Don't know. But having access to the uncompressed audio can only be viewed as a bonus. Sure it's a little inconvenient (having to capture everything twice) but a) nobody says you have to use it, and b) at least it's there!
Because then it wouldn't be an HDV camcorder. :)

Since there is TC, and we can capture HDV and then Batch Recapture all the clips as DV -- without video.

Think of the PCM track as if it was any "seperate sound" system.
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Old October 20th, 2005, 05:15 PM   #15
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how to capture PCM audio?

[QUOTE=Steve Mullen]Using FCP 5, I have now been able to capture from the FireWire port of the camera, a single PCM audio channel.

Steve,

Could you please detail the steps you used to capture this audio? I have tried many combinations of settings and nothing has worked. I am using HDV30p material with the BR-HD50 deck and FCP5.0.2. When both sides are set to DV the clips capture but there is no audio. When the deck is set to output DV on both the switch and menu there is no audio, but when either the switch or the menu is set to DV, FCP (which is in DV mode) does not recognize the deck, or tells me it cannot capture because there is no video (in spite of the fact that it is set up as an audio only capture). I'd love to know how you made it work.

Andy
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