JVC direct to hard disk

Discussion in 'Video Cameras' started by Beemer, Jan 8, 2006.

  1. Beemer

    Tony Morgan Guest

    AVI is NOT a digital video format, but is a container for one type of
    digital data or another. Within the header of each AVI file is what is
    known as a '4CC' code - which identifies what format that the AVI
    contains (or more accurately, what codec was used to produce the AVI).
    There is a free utility program, Gspot, which will tell you what type of
    digital data any particular AVI file contains and also tells you what
    (if any) codecs are available on your particular computer which can
    decode that AVI file.

    AFAIK there are no TVs that can display MPEG-2 without the video being
    first translated into an analogue video stream.
     
    Tony Morgan, Jan 12, 2006
    #21
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  2. Beemer

    Beemer Guest

    | | >
    | > | > |
    | > | | > | <snip>
    | > | >
    | > | > CONS
    | > | > The format used is lossy.
    | > |
    | > | <mode=pedantic>
    | > | Assuming that the OP is talking about consumer gear, I would hardly
    | > | call a DV5000 docked to a Firestore HDD unit (for example) as lossy!
    | > | </mode>
    | > |
    | > |
    | > Jerry,
    | >
    | > You mena lossy as in "jpg lossy"? The camera in which I am interested
    is
    | > one of the JVC Everio G range. Nothing in the literature mentions the
    | > file format. Spec is 1/3.6" ccd, 720x480 x 60i, 8.5Mbps cbr, 384Kbps
    | audio
    | > and that playpack on a TV is MPEG2.
    |
    | The solution Jerry was talking about uses a DV stream which is 28mbps. If
    | that's lossy - then it's a logical step that 8.5mbps is lossy.
    |
    | It sounds like the camera is saving the video as a DVD-compatible file,
    | which (for all but the most simple of cuts) should not really be used as a
    | basis for editing.
    |
    |
    | > I would be uploading to my computer for editing in Encore so the files
    | being
    | > edited would be AVI so no loss.
    |
    | AVI is a red herring - it means nothing more than the format the data is
    | stored on the hard drive. In itself, it says nothing about the format of
    the
    | video stream. That data is stored at a consistent location within the AVI,
    | and tells the registered playback program (or editor, or whatever) which
    | codec to use*. The codec can be lossless (such as uncompressed or HuffYUV)
    | or lossy (DV, DivX, XVID etc).
    |
    | With a sensible workflow, loss occurs in three places - in the digital
    | camera when the video is stored, in the video editing suite when the video
    | has to be recompressed (for example if you add titles, filter the colour
    | etc) and when you burn to DVD. In this respect, working with a DV AVI
    source
    | is not really any different to working with MPG source. It's just that
    the
    | DV file has a lower initial "loss" because it starts at a higher bitrate.
    |
    | The middle one of those three can be removed by an intermediate render to
    an
    | uncompressed AVI format. However, this is impractical for most users, and
    | takes up more time and a lot of hard drive space.
    |
    | Loss can occur in other parts of the workflow, but these are the main
    ones.
    |
    | * Deliberately simplified - I _know_ a system-wide DLL applies the codec,
    | not the application itself.
    |
    |
    Sorry I should have said that I would be editing in Premiere Pro not Encore!
    PP has Adobe Media Encoder which can output MPEG2-DVD format. I still do
    not know what encoding or data rate is used by the JVC Everio G camera
    range.

    Beemer
     
    Beemer, Jan 12, 2006
    #22
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  3. Beemer

    Tony Morgan Guest

    In message <lEnxf.25065$>, Beemer
    I would doubt that the data-rate at the various setting would be
    published by JVC. Nor would they quantify the quality at the various
    settings. However, on several of the revue/summary sites that can be
    Googled, it is said that "The GZ-MG40, with a 20-gigabyte hard disk,
    records 7 hours at DVD-quality; the GZ-MG50, with a 30-gigabyte hard
    disk records 10 hours of DVD-quality video".

    So if you want to record more before transferring to your PC you're
    going to have to accept a lower quality.
     
    Tony Morgan, Jan 12, 2006
    #23
  4. Beemer

    John Russell Guest

    LCD TV's connected via a digital video port should produce a display
    without an analogue stage.
     
    John Russell, Jan 12, 2006
    #24
  5. Beemer

    Tony Morgan Guest

    Really ?
    MPEG-2 ?
    Are you sure ?

    The LCD TVs with "digital input" that I've seen only offer the standard
    D15 connection (which is analogue) and/or DVI (which AFAIK is not
    MPEG-2), and/or SCART (again analogue). None of these are MPEG-2 (again
    AFAIK).
     
    Tony Morgan, Jan 12, 2006
    #25
  6. Beemer

    John Russell Guest

    For once the UK is getting an advantage by being late to the party. Those
    countries already with digital HDTV had to use MPEG-2. We have chosen to use
    MPEG-4. So I presume HDTV LCD's in those countiries can handle mpeg-2
    directly.
     
    John Russell, Jan 12, 2006
    #26
  7. Beemer

    John Russell Guest

    Oh, and also some LCD/plasma take the moduler approach of having the mpeg2
    sat tuner in a seperate box, but connected digitally, say by DVI. It's only
    then sematics to say that the "display" dosn't handle MPEG-2, as without the
    seperate Sat tuner box it can't really be called a TV.

    I could connect my PC now to to a Samsung LCD TV and play MPEG-2 files
    without analog being used at all. Come to think of it that's just what
    people do with their Media PC's.
     
    John Russell, Jan 12, 2006
    #27
  8. Beemer

    Tony Morgan Guest

    I really think, John, that you should read the last post of Beemer
    (which is to what I replied).

    You seem to be following the trend of Jerry and G Hardy in taking things
    out of context. Beemer suggested that he could connect the hard disk
    camcorder directly to his TV (not through a PC or any other "box) and
    output (from his camcorder) MPEG-2.

    Come to think about it, I haven't seen any Sat boxes that output MPEG-2
    as you seem to imply above.
     
    Tony Morgan, Jan 12, 2006
    #28
  9. Beemer

    John Russell Guest

    Your posts are always "absolute" in tone!

    No your implying that it's impossible to set up a modern digital TV system
    to play MPEG-2 files without reverting to analogue. A MediaPC with a PCI Sat
    card would work without analogue connection. You could connect the camcorder
    to it digitally, and display it's output without reverting to analog.

    A modern TV setup is not just a box in the corner!
     
    John Russell, Jan 12, 2006
    #29
  10. Beemer

    John Russell Guest

    P.S. the "it" in the above statement is the MediaPC, not the Sat Card!
     
    John Russell, Jan 12, 2006
    #30
  11. Beemer

    John Russell Guest

    P.S. the "it" in the above statement is the MediaPC, not the Sat Card!
     
    John Russell, Jan 12, 2006
    #31
  12. Beemer

    Tony Morgan Guest

    You really are getting me confused now John. I've got a PCI AverTV DT
    card in my PC, and I still fail to see how I (or anyone) can get an
    MPEG-2 output to any display - be it a TV (glass or LCD) or to a monitor
    (glass or LCD). Even DVI doesn't transfer video as MPEG-2 (my LG 782 is
    fed via DVI).
    I didn't suggest for one moment that it was. But (again) AFAIK the only
    way digital video can be input to a TV or monitor (glass or LCD) is via
    the DVI port, and that certainly is not (nor does it carry) MPEG-2. And
    again I should remind you that Beemer was asking about connecting to TV
    via MPEG-2.

    Since you seem to know what you are talking about, I'd really appreciate
    it if you could let me know which make/model of TV accepts MPEG-2 as
    input video. I'm sure Beemer would be interested as well.
     
    Tony Morgan, Jan 12, 2006
    #32
  13. Beemer

    G Hardy Guest

    Encore!

    To be honest - it doesn't really matter. I don't use either product, but as
    far as I'm aware most editors have a "smart" render setting where files that
    have the same specification as the project will be copied byte-for-byte
    instead of being re-rendered (as long as the clip has been cut, rather than
    the video appearance being changed). Where the project settings are lower
    than the source file settings (e.g. source video is 8.5mbps, target is 6.5)
    the video will be rendered. Where the source file settings are lower than
    the project settings (e.g. source video is 6.5mbps, target is 8.5) the video
    will be left as-is.

    You can't "add" quality, so there is no benefit at all in any editing
    package re-coding the video up to a higher bitrate. If it does - avoid it!

    Well according to the specs you posted (reproduced above), it's 8.5mbps
    MPEG-2. :eek:)

    This is actually quite high - you could probably get away with one or two
    re-renders at that rate. In fact, you should do at least one render for your
    DVDs to get the total data rate (audio + video) down to about 6.5mbps. It's
    unlikely the resulting loss in quality will be noticeable, but a data rate
    between 5 and 6.5 dramatically improves compatibility of your DVDs with
    set-top players.
     
    G Hardy, Jan 12, 2006
    #33
  14. Beemer

    John Russell Guest

    Acer, for example, produce LCD TV's where the display is a dumb device. All
    the inputs and tuners are in an external box. connected via digital link.
    Some Plasma's also take this route. The simple reason is such a display
    will also satisfy those people interested in MediaPC's as they only require
    a dumb display.

    Youv'e got to stop thinking in terms of box's, and think interms of
    function. A Tv is a display connected to TV tuner. It dosn't matter
    functionally if the latter is in a separate box.

    The bottom line is it is possible now to buy the neccessary sub-sytems
    which together make a TV System where mpeg-2 files can be played and
    displayed without analogue being involved.
     
    John Russell, Jan 12, 2006
    #34
  15. Beemer

    G Hardy Guest

    No, not MPEG-2, but not analogue either.

    These days, it makes sense for the signal decoder to be separate from the
    viewing screen. There are just so many standards to choose from :eek:)
     
    G Hardy, Jan 12, 2006
    #35
  16. Beemer

    G Hardy Guest

    Tony, if you frequent a group filled with lobotomised woodlice (your
    declaration), you should expect the occasional inane argument.

    Well to anyone else reading the thread, that's not what was implied. Please,
    everyone - speak up if you read it either way - let's have a straw poll.
    Perhaps we can put to bed once and for all the denizens of this NG who take
    things out of context.
     
    G Hardy, Jan 12, 2006
    #36
  17. Beemer

    John Russell Guest

    At that video rate + a typical DD audio rate , it would still be within the
    max rate of a DVD. I would consider using dual layer disks to avoid
    re-rendering if doing so was totally transparent to the process. Little
    point losing quality just becuase you want to use particuler software, or
    stick to single layer disks.
     
    John Russell, Jan 12, 2006
    #37
  18. Oh dear, here we go again.

    All mpegs are video compression.

    ie.

    they compress (encode) the original picture information

    therefore they need to be uncompressed (decoded) before the picture can be
    displayed.

    Everybody should know that.

    The decoded digital data can be sent and displayed directly on a TV/Monitor via
    a DVI-D connection. No analog involved.

    The decoded digital data can also be converted to various analog signal types
    and displayed on a TV/Monitor.

    Everybody should know that.

    AFAICS, all you're arguing about is what piece of equipment decodes the mpeg2
    stream.

    If Tony is saying that there are no TVs with built in mpeg2 decoders then he's
    incorrect. LCD/DVD combined units have built in mpeg decoders Freeview sets
    have built in mpeg decoders. (True HDTVs also need built in decoders - currently
    only Never The Same Color available)

    However, if he's saying that no TVs with built in mpeg2 decoders that can
    directly take an external mpeg compressed stream, decode it and display it, he's
    probably right as I don't know of any yet. However, with USB ports etc becoming
    standard on HDTVs, I wouldn't be surprised if we didn't see one soon.

    Hope this helps before this gets out of hand :)




    regards

    Stuart

    www.mckears.com
     
    Stuart McKears, Jan 12, 2006
    #38
  19. Beemer

    G Hardy Guest

    It's nothing to do with authoring software, and everything to do with
    (combined) data rate.

    It's irrelevant that the maximum data rate specified by the DVD forum is
    10.05mbps, and the maximum _sustainable_ data rate is 9.8mbps. If you use
    those rates as your guidelines, you will _not_ be maximising compatibility
    of your discs.

    My neighbour brought his daughter's wedding DVD back from Vegas and it
    wouldn't play on his machine. The video was 8000kbps, audio 1536kbps. I
    ripped it, converted the audio to DD and re-burned (leaving it as NTSC) and
    it now plays fine.

    For typical consumer footage, a VBR video stream average 5.5mbps, max 7mbps,
    with CBR audio 192kbps will cope with the most demanding footage Joe Public
    can throw at it. If it's relatively static (e.g. a wedding), CBR video at
    6.5mbps will be fine.

    Going higher is counterproductive - even if it means there will be space
    left over on the DVD.
     
    G Hardy, Jan 13, 2006
    #39
  20. Beemer

    John Russell Guest

    Do you really think the future is large flat screen, probably wall mounted,
    with all the input cables dangling from the bottom, including USB?

    No, the future is going to large flat wall mounted displays, with the
    electronics in a seperate box, connected by a single digital video/audio
    cable. The two together make up your TV System. Plasmas's have been like
    that for years.
     
    John Russell, Jan 13, 2006
    #40
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