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Old February 18th, 2005, 07:19 AM   #1
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DVCAM on MiniDV

I'm sure I read here most people tend to shoot in DVCAM mode on MiniDV tape (PD150 etc) but I'm sure I read on SimplyDV that this has caused problems for people.

Is it worth it? Surely there's some difference in the tape if MiniDV tapes cost about £3 here, and MiniDVCAM tapes cost £10 (I don't think its a case of just paying for the name)

No point filming in a more secure format if its not going to me more secure at all !
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Old February 19th, 2005, 11:58 AM   #2
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I' worked a lot with PD150 and shot about 60 DV tapes (Sony) in DVCAM mode. Never experienced any problem, so from my point of view thing works!
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Old February 20th, 2005, 06:38 AM   #3
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Thanks, when I'm shooting properly thats the road I'll go then. Alas I can't afford so many tapes where I can only shoot for 40mins (I do lots of gigs, so 5 bands would mean 5 tapes. Sometimes I've done 4 gigs over 7 days. Ouch!) but when doing proper music video work in the future I can. Cheers :)
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Old March 7th, 2005, 11:42 AM   #4
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Does this get DV quality out of miniDV

Hope this is the place to post this...just did searches etc and couldnt get much out...


I've interpreted something in a uk computer arts mag as meaning that it is possible to get DV quality from mini DV at the expense of tape duration dropping to 40 mins.

Thats all i know....is it the case? what are the issues? what particular settings on a GL2 (uk pal XM2 actually) do i need.

many thanks.
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Old March 7th, 2005, 12:12 PM   #5
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What exactly are you asking? DV is DV. The only difference between miniDV and Full Size DV is the size of the case and the amount of tape it holds. The quality is exactly the same. If it's DVCAM you meant to say, DVCAM is only available on Sony cameras (well, and Ikegami too) but it is not available on Canon cameras. The image quality is the same as regular DV. The added benefit is that DVCAM records locked audio, SMPTE Time code, and a little more information on the tape. That's why you only get 40min out of a 60min tape. It runs the tape faster. The intention is that the more robust recording would hold up to editing where you move the tape a lot more and thus risk damaging and degrading the tape and causing dropouts. Functionally though, there isn't supposed to be a "visual" difference from regular DV.

I also use regular DV tape to shoot DVCAM on and have never had a single problem doing it. I do also use the DVCAM tape on occasion but it just cost's more.
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Old March 7th, 2005, 05:40 PM   #6
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I believe DVCAM runs the tape faster to allow insert editing.

Adam wilt's DV FAQ has a whole sub-section on it.
http://www.adamwilt.com/DV-FAQ-tech.html#DVformats

What's the difference between DV, DVCAM, and DVCPRO?
Not a lot! The basic video encoding algorithm is the same between all three formats. The VTR sections of the US$20,000 DVCAM DXC-D135 or US$17,000 DVCPRO AJ-D700 cameras will record no better an image than the lowly DV format DCR-VX1000 at US$4,000 (please note: I am not saying that the camera section and lens of the VX1000 are the equals of the high-end pro and broadcast cameras: there are significant quality differences! But the video data recorded in all three formats is essentially identical, though there may be minor differences in the actual codec implementations). A summary of differences (and similarities) is tabled in Technical Details.

The consumer-oriented DV uses 10 micron tracks in SP recording mode. Newer camcorders offer an LP mode to increase recording times, but the 6.7 micron tracks make tape interchange problematic on DV machines, and prevents LP tapes from being played in DVCAM or DVCPRO VTRs. Sony's DVCAM professional format increases the track pitch to 15 microns (at the loss of recording time) to improve tape interchange and increase the robustness and reliability of insert editing. Panasonic's DVCPRO increases track pitch and width to 18 microns, and uses a metal particle tape for better durability. DVCPRO also adds a longitudinal analog audio cue track and a control track to improve editing performance and user-friendliness in linear editing operations.

2- Theoretically, DVCAM recording would need lesser quality tape since running the tape faster makes it more robust?
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Old March 7th, 2005, 07:00 PM   #7
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> Theoretically, DVCAM recording would need
> lesser quality tape since running the tape faster
> makes it more robust?

Yes. But you know the saying about the difference between theory and practice, don't you?
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Old March 8th, 2005, 02:15 PM   #8
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thanks for all responses,

For clarification my question was prompted by 'computer arts' magazine

"...you can actually shoot DVCAM format on standard miniDV tapes........common money saving technique in the industry......enabling you to gain higher resolution footage from a miniDV tape"
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Old March 8th, 2005, 02:20 PM   #9
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"You can actually shoot DVCAM format on standard miniDV tapes... enabling you to gain higher resolution footage from a miniDV tape"

Just so there is no confusion, that statement is wrong.
While it's true that you can shoot DVCam format on a miniDV tape, the resolution between DV and DVCam is exactly the same.

Just didn't want anyone getting the wrong idea if they glossed over that.
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Old March 9th, 2005, 04:04 PM   #10
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There's no 50mbps DVCAM mode, although the DVCPRO format has 25mbps, 50mbps (DVCPRO 50), and 100mbps modes (DVCPRO HD).
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Old March 9th, 2005, 04:15 PM   #11
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To expand on that -- there is no DVCam50, and DVCPro50 does not record on metal evaporate tapes -- you can't record DVCPro50 (or DVCPro100) on DV or DVCam tapes.

As DVCPro 'ordinary' is the same as DV & DVCam, you can record it to DV tapes ... but I don't own that gear & don't know if you can actually insert those tapes into the deck. Originally, DVCPro used a medium sized cassette & a full size cassette, but not the mini size available for DV & DVCam -- maybe this is still so.

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Old March 16th, 2005, 04:12 PM   #12
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If I use a MiniDV tape, and record in DVCam mode w/ my PD-150, can I still get locked audio/SMTPE timecode, or do I actually have to record in DVCAM mode onto a DVCam tape to get that?

Also, the article states that 44.1 audio is never locked and DVCam locks at 48 or 32.

Maybe I am confused here, but I thought that the PDseries cameras can record in 44.1 not 48. So does it actually lock the 44.1/16 audio, or does it actually record 48/16 when running in DVCam mode?

Lastly, don't many NLEs expect 44.1/16 audio (like Premiere or DVXpress)? IOW, when dumping DVCam video via FW to the PC do I need to set up the "project" in my NLE differently to accept the higher bitrate audio? Or will it just accept what it gets?

Thanks,

Alex F
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Old March 16th, 2005, 04:51 PM   #13
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Alex, you can use a any MiniDV tape in your PD150 and record in DVCam mode. You will get the benefit of locked audio and extended timecode. You will also supposedly get the benefit of a lower error rate, although I have yet to see this make a real life difference. Whoever you buy tape from will also get the benefit of slightly more business, because 60 minute tapes will only last you 40 minutes, so you will need to buy more tape.

Your Sony rep will tell you that the more expensive DVCam-branded MiniDV tape is better but --as Rhett suggests earlier in this thread-- it seems to be just the same tape in a different package, so don't fall into the trap of buying it. Just buy standard DV Sony MiniDV tapes and use the in DVCam mode if you prefer.

With the NTSC PD series cameras, audio in unlocked mode is still in good sync and timecode is always recorded with DV, although without the extra user bits, so in my opinion the normal DV SP mode is quite ok.

Interestingly, in PAL DV audio is always locked. As usual, euroeans have the edge, but I'm getting off-topic.

I have not seen any camera that can actually record at 44.1 KHz analog, including the PD150. Although 44.1 KHz is part of the DV spec and if you send audio at that sampling rate to a Sony camera through Firewire, it will probably record it to tape. It will also play tapes with 44.1 KHz audio. But there is no way you can use it in camera mode or pass-through mode and have it capture 44.1 KHz audio.

Premiere can use 48 KHz audio through Firewire, but your PC's hardware might not support more than 44.1 KHz on it's sound card, so make sure you monitor through Firewire using the camera in VTR mode (which is also a good way to monitor the video, just connect a monitor to the camera) instead of trying to monitor through the PC speakers. Bitrate is 16 at 44.1 KHz or 48 KHz bits, but you need to make sure the sampling rate for the project is set to 48 KHz before importing.
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Old March 16th, 2005, 07:21 PM   #14
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1) 'Locked' audio has nothing to do with sync -- it is a simple process of ensuring that every video frame end will always tie to an audio frame end, so that in a deck-to-deck tape edit you will never truncate a frame. Only useful for deck-to-deck edits, a 'legacy' system that Sony expected the commercial/news market would use. Now that everyone uses NLE for everything, the locked audio thing is relatively useless ... and it never had anything to do with sync;
2) 44.1 audio is part of the DV spec, I believe that you can choose to record to 44.1 audio on some devices ... but I don't know of one, or at least none I've owned have had the option.

I'd stick with 48k 16bit audio -- buy a new $30 audio card if yours doesn't support it. I have never had problems with DV drop-outs, but I use DV tape in DVCam mode when shooting for a client ... I bill them for the tape either way, and DVCam mode lets me follow the convention of setting the timecode hour to indicate which tape it is -- for Sony devices you can only 'set' timecode in DVCam mode.

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Old March 17th, 2005, 08:42 AM   #15
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> and it never had anything to do with sync

Actually it does, but it is very subtle. Because there is no exact numerical relationship between NTSC's 29.97 fps and 48 KHz, audio and video are locked to seperate clocks in consumer gear, which are not locked to each other --thus the term "unlocked"-- so when playiing a DV tape the audio and video actually can and do drift slightly out of sync and back again the amount of almost one field, but should maintain sync in the long run. At least this is what happens with good, stable cameras like the Sony's in unlocked mode. If you have the patience you can actually see it on a time line on a frame by frame basis, assuming your NLE displays accurate fields and waveforms. With some cameras, the sampling rate is simply changed to something slightly different, a very sloppy solution indeeed. Early Canon cameras grab 48kHz sound at around 48.009 kHz, which can result in almost a second of video/audio slippage over the course of an hour (or around one frame every two minutes). This doesn't affect sync when a DV tape is played back, since the DA converter on the deck or camera clocks to the embedded clocking data coming off the tape. But when audio and video are processed independantly of each other, audio played back at 48 Khz and recorded at a slightly different sampling rate will have a different duration and will thus drift out of sync. Most pro NLE "know" about this and are programmed to compensate, but some do not and this can result in noticable drifts with long takes.

Of course synchronizing both clocks to a master clock requires more complex circuitry, which is why only the more expensive gear does this. Note that this is not limited to Sony DVCam. DVCPRO has locked audio and professional JVC cameras record locked audio onto standard MiniDV tapes in DV SP mode, and as I mentioned earlier PAL audio is always "naturally" locked, because 25 fps and 48 KHz can be easily driven from the same clock.

Sorry for the long post. There is much more to this: http://www.adamwilt.com/DV-FAQ-tech.html#LockedAudio
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