Discussion in 'Video Cameras' started by Marc Down, Oct 2, 2006.

  1. Marc Down

    Marc Down Guest

    I've been thinking about that after downloading the Avid software. I know
    that Firewire is the de-facto standard for video work - but isn't USB 2
    faster? If it is faster, why is Firewire still the norm?
    Marc Down, Oct 3, 2006
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  2. Marc Down

    Marc Down Guest

    Managed 28 minutes @ 14mb per minute before it froze again (that was using
    s-video through a Dazzle converter and Movie Maker, with all background
    programmes stopped by enditall)

    That's not such a problem - it's only when viewing the tapes again that you
    realise just how much rubbish in on them! - from a 60 minute DV tape I'll be
    lucky to get 15 minutes of worthwhile footage.

    My stash of old VHS tapes can presumably be captured in chunks to avoid
    seizing? - I doubt if there is more than 28 minutes of any particular
    unbroken sequence.
    Marc Down, Oct 3, 2006
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  3. Marc Down

    Jerry Guest

    On paper it is faster, but in the real world it isn't, in the same
    way as no motherboard is capable (at the moment) of sustaining the
    maximum stated data rate that SATA hard drives can achieve on paper.
    Jerry, Oct 3, 2006
  4. And a lot of USB video capture devices AREN'T USB2.
    Laurence Payne, Oct 3, 2006
  5. Marc Down

    Jukka Aho Guest

    I'm not sure if Avid Free DV can capture new material straight from your
    Dazzle capture device, but if you capture your source clips in another
    app, I think you should be able to import them to Avid Free DV.

    What is the exact model of the Dazzle device you're using for capturing?
    Which format (codec) does it use for the captures?
    Jukka Aho, Oct 3, 2006
  6. Marc Down

    Jukka Aho Guest

    Bandwidth is not an issue. DV is only 25 megabits per second. But
    Firewire was there first, and DV camcorders got designed around it.

    There is one technical difference that makes Firewire better suited for
    AV devices: USB is a directional, host-centric protocol whereas Firewire
    is an equal-opportunity peer-to-peer protocol. For instance, you can
    connect two DV camcorders with a Firewire cable and record directly from
    one to the other. The USB bus, on the other hand, even uses different
    physical connectors for "upstream" and "downstream" devices (type "A"
    and type "B" USB connectors) so that you couldn't accidentally connect
    two "hosts" together, or two "slave" devices together (because it just
    wouldn't work that way.)
    Jukka Aho, Oct 3, 2006
  7. Marc Down

    Jerry Guest

    If he wants to do that he could go down to Dixons (etc.) and buy a
    DVD recorder, unless he wants multiple copies, even then it would be
    cheaper to upgrade his capture card / software.
    Jerry, Oct 3, 2006
  8. Marc Down

    Jerry Guest

    IIRC Avid Free DV only works with DV files.
    Jerry, Oct 3, 2006
  9. Marc Down

    Jerry Guest

    Might be true for USB2 and on paper, but in the real world USB can
    not support the continuous data stream that DV delivers during
    capture, USB is OK were data burst or data buffering can be used. I'm
    not sure how the Avid Edition BOB works, but even so, it's very picky
    about what USB control chipsets it can work with.
    That can't be correct, otherwise USB broadband modems couldn't work,
    and printers couldn't send error messages back to the computer!
    Jerry, Oct 3, 2006
  10. Marc Down

    Tony Morgan Guest

    Not true AFAIK. A to A are readily available. Another example is the
    increasingly popular USB2 Flash memories which permit writing and
    reading via an A (male) to A (female). Then of course are the many
    digital still cameras that use A (male) to miniature A connectors. Both
    USB2 and Firewire are capable of simultaneous data transmission in both
    directions. One very common example of USB2 (and USB1) is the now common
    printer/scanner/memory read/write. Another is the ability to connect
    (say) a scanner and printer via a hub where the hub--->PC connection is

    For examples of the many USB connection possibilities try:
    Tony Morgan, Oct 3, 2006
  11. Marc Down

    Tony Morgan Guest

    I've looked back through your earlier posts Marc, and though you don't
    specifically say so, I'm assuming that you are transferring *from* VHS.
    If that is so then quality is not quite such an issue. This is because
    the quality of VHS (measured in lines) is only 240. You can't improve on
    what you started with.
    Tony Morgan, Oct 3, 2006
  12. Marc Down

    Marc Down Guest

    Yes, I have many VHS tapes dating back over 20 years. They were all
    recorded on full size VHS cameras on good quality TDK's, and the quality is
    surprisingly good (no dubbing or generational loss from VHS-C) In fact, the
    quality is not too far below that obtained from my later camcorder, JVC
    GVX - although, that was a first generation DV model with analogue output,
    so I don't suppose that particular camcorder really reflects true DV

    But, as you say, apart from three DV tapes, my entire output will be from

    Now that I've dug out the GVX from a cupboard I might start using it again -
    although, I,m very tempted to pass on my proposed replacement DLSR camera
    and invest in a new camcorder, perhaps one that writes to hard disk.
    Although it's been a bit messy getting this set up, I'd forgotten just how
    much fun is to be had with video as opposed to digital photography.
    Marc Down, Oct 3, 2006
  13. Marc Down

    Andy Champ Guest

    Master-slave (as with USB) is NOT the same as unidirectional. it just
    means that the master tells the slave when to talk.

    IAC the main advantage of Firewire over USB is that the CPU doesn't have
    to work as hard.

    Andy Champ, Oct 3, 2006
  14. Marc Down

    G Hardy Guest

    That would make my wife "master" then?
    G Hardy, Oct 3, 2006
  15. Marc Down

    Tony Morgan Guest

    USB2 is step-down (in speed). IEEE1394 is not. 1394 does, however,
    support either 100. 200 or 400Mb but it's not step-down. In practice,
    1394 invariably runs at 400Mb (as defined by the appropriate 1394TA

    Another advantage of 1394 is that associated with the 1394TA where
    particular applications are standardised, so that (for example) all
    video cameras' control protocols are standardised.

    On a more practical level, USB *should* (according to the standard)
    source 500mA at the A end to provide power to the B end. This
    incidentally often causes problems for 1394, since both sit on the PC's
    PCI bus, tracks of which are relatively insubstantial and are decoupled
    to provide noise from affecting other PCI devices. The decoupling
    components introduce (when loaded) a voltage drop, sometimes introducing
    mis-operation of other peripheral cards on the PCI bus - particularly
    the 1394 card. This problem is *supposed* to be countered by a direct
    power feed from the PC's power supply to the USB card; most USB cards
    provide a power-in socket (with exactly the same pin configuration as
    that of your hard drive); so the USB *should* be powered via the hard
    drive's daisy-chain connector. Sadly few PC manufacturers connect this.
    Often firewire problems can be fixed by connecting this external power
    feed - either by a spare plug on the hard drive's power connector, or by
    buying and fitting an additional "daisy-chain" connector. In other cases
    the 1394 problem can be temporarily fixed by disconnecting all USB

    So for all you video guys out there, I'd suggest that you have a look to
    see if your USB card has an unconnected power-in socket - if so, connect

    There are other issues associated with IRQ polling; there's something
    about this (and how to fix it) at:
    http://www.camcord.info/tuning under Windows & Firewire Communication.

    But I digress with this "Information Overload" :)
    Tony Morgan, Oct 4, 2006
  16. Marc Down

    Tony Morgan Guest

    That depends on who wears the handcuffs and who wears the leather mask
    and carries the whip :)
    Tony Morgan, Oct 4, 2006
  17. Marc Down

    G Hardy Guest

    Oh - I thought it was just based around who gave permission to talk...
    G Hardy, Oct 4, 2006
  18. Marc Down

    Jukka Aho Guest

    As far as I can see, it would appear to import and export AVI and
    QuickTime material with arbitrary codecs installed in your system - such
    as in the M-JPEG format, which is what many older capture devices use.
    Jukka Aho, Oct 4, 2006
  19. Marc Down

    Jukka Aho Guest

    The USB FAQ (by USB Implementers Forum, Inc., "a non-profit corporation
    founded by the group of companies that developed the Universal Serial
    Bus specification") calls A to A cables "illegal" and suggests they're a
    fire hazard:

    -- 8< ---

    Q5: How can I connect two PCs to each other with USB?
    A5: You need a specialized USB peripheral known as a USB bridge
    (sometimes called a USB to USB adapter) to do this. Anchor Chips and
    e-Tek labs, among others, make USB bridges.

    Q6: You mean I can't make a direct cable connection like a null modem?
    A6: Correct. In fact, if you try this with an illegal A to A USB cable,
    you'll short the two PCs' power supplies together, possibly destroying
    one or both machines or causing a fire hazard. Even there were no danger
    to the machines from the problem with two power supplies, there still
    wouldn't be any way to get the two PCs talking to each other, since USB
    doesn't support that particular kind of communication. A reasonably
    priced solution to handle this need is the USB bridge.

    Q7: So why do people make A to A cables, anyway? What kinds of cables
    do I need to connect USB devices together?

    A7: A number of cable vendors seem to have reached the conclusion that
    USB is like a PC's serial port, only faster, so you need all sorts of
    special hardware to create the USB connection you need to make. This is
    completely incorrect. The only kind of cables you'll ever need to
    connect normal USB products are A to B cables, A to mini B cables or
    mini A to mini B cables of various lengths. Some special kinds of
    devices use nonstandard connectors and so come with their own special

    -- 8< ---

    There's nothing wrong with that - male to female is just an extension
    cable. But standards-compliant USB devices should not come with or
    require the use of A (male) to A (male) cables.
    Some manufacturers do the funniest things.
    But of course. That has not been disputed. Still, one of the devices -
    the root in the topology - is the "host" and the other devices in the
    same bus are "peripherals", whereas Firewire is peer-to-peer and does
    not make that distinction.

    Apparently the problem with this has been acknowledged, though, since
    the powers-that-be have later defined a new standard called "USB
    On-the-go" (or "USB OTG" for short), where devices can change around
    their "host" and "peripheral" roles, if needed:


    (This was not what the original USB standard defined, though, so not all
    USB devices are like that.)
    Jukka Aho, Oct 4, 2006
  20. Marc Down

    Jerry Guest

    What sort of video films did you say you make Tony?!.. :~)
    Jerry, Oct 4, 2006
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