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ADVC110 vs. ADVC300

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  • GrassValley_BH
    replied
    You're right Kenneally...

    I think the point where we started getting confused was the difference between the signal format, being PAL (50 Hz interlaced, or 25 fps) and the scientific signal timing measurement.

    As long as your signal is "regular" PAL, 50 Hz interlaced, then the ADVC is compatible with it.

    As for the exact signal timings, the video sync is embedded into the signal (in the vertical interval), so the receiving device will detect and drive off of that sync.
    Since as you say, nothing is 100% absolute, there's a good deal of tolerance there, especially in an analog world where things just "flow through."

    However, in the digital world, things are far more cut-and-dry and hence less tolerant. If the sync is sufficiently off, then a frame may be lost.

    The ADVCs generally time off of the embedded sync in the video, and if a video frame is missed, the corresponding audio frame is also missed, keeping the audio and video in sync with each other. Of course the higher-end ADVCs have Reference I/Os so you can genlock for recording and playout.

    The ADVCs do need a full frame, they don't handle partial frames very well, if at all, which is why the DV signal will be interrupted if you disconnect the video cable or encounter a truly blank area of tape (that has no sync signal).

    Most of the newer ADVCs also have a choice between internal clock and external clock. The internal clock option uses an internal clock, while the external clock will sync off of the FireWire clock.

    The higher-end ADVCs have PerfectSync which is a process that synchronizes the FireWire clock with the ADVC to ensure there are no skipped or repeated frames.

    Regardless, the ADVCs are very, very good at maintaining audio/video sync, and that is a large reason why we get a lot of folks who have moved over from competing products.

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  • GrassValley_KH
    replied
    Brandon's probably more the expert here, but correct me if I'm wrong - if your VCR wasn't outputting a 50hz (PAL) signal, your telly wouldn't be showing you a picture, even if only momentarily.

    So in turn, if your equipment isn't outputting 50hz, ADVC too would see a dropout - because your source equipment isn't doing its job right. This would mean that the ADVC would simply breakup the signal in the same way a display would - (missing) black frames. And that's the biggest sign that either the VCR is stuffed, or the tape is. :)

    Now for Brandon to tell me I got it completely wrong...

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  • kbosward
    replied
    I don't think anyone here is quite sure what you're asking. In the analog to DV conversion, the ADVC110 simply needs to capture each frame from the analog signal, compress it according to the DV standard, and feed it into the DV stream that is captured by the computer. The ADVC110 sets the attribute flags in the DV stream to indicate it is 25 fps (for PAL).

    So let's say your VCR is somewhat inaccurate and sends a signal at 24.9 fps. The ADVC110 would still capture this a frame at time and send the resulting DV stream to the computer, which saves it to disk. Presumably the ADVC110 has circuitry which waits until a whole frame is captured before converting, it doesn't just blindly take a snapshot at a point in time and hope it has a whole frame. Of course I'm only guessing that's how it works, but I can't see how else it could work.

    When your playback software reads the DV file, it sees that it should play it at 25 fps and does so.

    If you think of the ADVC110 as a device that captures frames, then it is not a problem.

    Ken.

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  • 2Bdecided
    replied
    Originally posted by GrassValley_BH View Post
    Not sure why your VCR wouldn't be 25 fps?
    Let me put it another way...

    I don't have any knowledge of how the ADVC110 or the Firewire interface work. All I know is that there's a format which we call "DV" which sends ~25Mbps video data over that Firewire interface. For PAL, it's at 25fps.

    Somewhere I assume there's a master clock for the conversion, and 25fps is this clock divided by some number (it could be 13.5MHz / 540000 to get 25fps - that would be the case for DVD, but I don't know about DV).

    The A>D conversion must be driven by a clock from somewhere, but where? From a clock on the Firewire bus, or by a clock in the ADVC110, or by a clock PLL'd to the incoming video signal?


    Nothing in this world is exact, and no video is exactly 25.000000000000000000000000fps. So given that my analogue video is coming out of a piece of machinery where the video rate is dictated by magnetic particles on a tape, read by a spinning piece of metal, moved by motors driven by servos, it's a safe bet that the "25fps" coming out of the VCR will not match the "25fps" derived from a 13.5MHz (or other) crystal (or other) clock.

    So, what do your ADVC devices do to reconcile this? Is the DV output effectively (directly or indirectly) clocked from the incoming video, and DV Firewire interface is "OK" with this? Or is the DV clocked from the ADVC110 or the PC bus? If it's the latter, how is the incoming (independent!) video signal made to fit to this clock which it has no knowledge of, and is not slaved to?

    In short, do you have to drop or duplicate frames to keep up, or is there another method?


    I guess I'll find out when my ADVC110 arrives in a few days, but if you know the answer, I'm still interested!

    Either way, many thanks for all your help BH.

    Cheers,
    David.

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  • GrassValley_BH
    replied
    Not sure why your VCR wouldn't be 25 fps?

    As far as the sync goes, essentially the ADVC will try to lock audio samples onto the video clock, hence maintaining audio/video sync.

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  • 2Bdecided
    replied
    It's standard PAL, but an analogue signal can't be "exact", can it? I don't think my VCR includes an atomic clock! So I was wondering how these devices make up the difference between the 25fps of the ADVC110, and the not-quite-the-same 25fps of the VCR. Especially as the audio has to remain locked.

    Cheers,
    David.

    Leave a comment:


  • GrassValley_BH
    replied
    If the input isn't standard PAL then it likely will either get confused, or it may not even display/encode the signal at all.

    For example, in the NTSC world there exist true monochrome NTSC devices that output 30 fps (versus color NTSC which is 29.97 fps), and the ADVC can't capture that.

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  • 2Bdecided
    replied
    Thank you for your help! I will go and research TBCs and pre-amps.

    Any idea how it handles video signals that aren't exactly 25fps?

    Cheers,
    David.

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  • GrassValley_BH
    replied
    Get the ADVC110 (over the ACEDVio because it's portable and can be better isolated from interference from the computer), a audio pre-amp or mixer for the audio, and an external video pre-amp or TBC. This setup is more components, but will give you a great amount of control.

    Both the 55 and 110 will maintain audio/video sync. There's a slight technicality in the definition of locked audio which keeps us from saying the 55 has locked audio. For the general definition of "synchronized audio/video" all ADVCs address this.

    I usually recommend that people get the 110 over the 55, unless you are absolutely certain that you will not be using the output (which can be very useful for editing, checking color correction, etc).

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  • 2Bdecided
    replied
    I am so pleased to find this forum! I am trying to decide between the various Canopus ADVC boxes, or a DV/Digital8 camcorder.

    I'm in the UK, and have about 100 hours of PAL S-VHS camcorder footage to transfer (~1992-1997), plus a little VHS (1984-2001!). Most of the tapes are S-VHS copies from S-VHS-C masters, though I have a few surviving S-VHS-C masters straight out of the camera too.

    I have a Panasonic NV-SV121EB deck with built-in TBC (works well) and DNR (can do better myself in software). Obviously I'll use the S-video output. Being in Europe means it's quite hard (not impossible) to find a camcorder that will take S-video in and send it out over Firewire.

    So, I was looking at the ADVC300, but I see that you can't turn the noise reduction off completely. That's a shame, because I can do wonderful noise reduction via AVIsynth scripts, and I want to capture raw. The ADVC300 TBC probably won't help more than the one built in to the VCR, so that's no benefit.

    However, the ADVC300 lets you adjust the video input level, and has an AGC. That may be really important, because the highlights on these tapes have a tendency to blow out when digitised via the capture card (Dazzle Hollywood DV bridge :yuk:) and DVD recorder (Sony GX300) I've tried. The highlights aren't as bad on the tape itself - you can see this on a TV, and the digital files have "clipped" RGB value (255,255,255!) which should never be hit if the levels are set properly.

    So, do I go for the 300, set the levels, but get unwanted filtering - or do I go for the 110, hope the levels are OK, but avoid unwanted filtering? Or something else?

    Also, the ADVC55 is mentioned near the top of this thread as being equivalent to the 110 - however, the Canopus website lists the 110 as having locked audio, but doesn't mention this for the 55. Can anyone confirm whether the 55 has locked audio? I probably don't need the outputs of the 110.

    Finally (tech question) given that the analogue input video will never be exactly 25fps, what do the Canopus boxes do to generate 25fps DV? Drop/duplicate frames? Or something more clever?

    Cheers,
    David.

    EDIT: P.S. is the ACEDVio a fine substitute for the ADVC110? I see it has locked audio, the same converter chip, and also some video controls.
    Last edited by 2Bdecided; 11-28-2007, 01:39 PM.

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  • kbosward
    replied
    Originally posted by hal 123 View Post
    I understand that the ADVC 300 image enhancement features are not available for PAL input.
    I remember from reading the old forums that it was only the 3D Y/C separation that does not work in PAL, and the PAL purists would say that the reason for this is that it was not required due to PAL's inherently superior colour fidelity compared to NTSC (Never The Same Colour). Of course you can take that how you like :)

    I regularly use the ADVC300 with PAL sources on old VHS and Video8 tapes and I can tell you that the image processing features are very welcome and noticeable.

    Some in these forums have said that the ADVC300 can reduce the quality slightly for very good video sources (Hi-8 using S-video connection) since the LBTC cannot be switched off. However if your sources are Video8 then I would definitely say go for the ADVC300 if you can afford it.

    Ken.

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  • GrassValley_KH
    replied
    My knowledge is a little hazy, but I believe there's still a few of the image correction features that apply to PAL footage as well (ie, not NTSC exclusive).

    That said, if the feature you need is definitely not supported with PAL input, you'll save some dollars going for a lower model - the actual conversion quality is the same, since it's the same chip.

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  • Guest's Avatar
    Guest replied
    ADVC110 vs. ADVC300

    On a similar theme I also wish to capture old video 8 tapes (PAL) into AVI format for preserving the footage and future editing.

    I understand that the ADVC 300 image enhancement features are not available for PAL input. For my purpose should I consider the ADVC 110 / 55 or would the ADVC 300 be better for my 'old' tapes some of which are 16 year old. Many thanks.
    Last edited by hal 123; 11-26-2007, 02:47 PM.

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  • GrassValley_KH
    replied
    Yes, it does.

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  • Guest's Avatar
    Guest replied
    Originally posted by GrassValley_BH View Post
    5x, 1x0, 500, 700 and 3000.
    Does the ACEDVio have the same chipset as the other cards listed? I am interested in Analog-to-Digital conversion only, VHS tapes.

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