10021 Views 2 Replies Latest reply: Oct 31, 2008 8:49 AM by SDIllini
Home video, when it went 'digital' (..as distinct from the older analogue formats like VHS, Video-8, Hi-8, S-VHS, etc..) took two forms: DV (Digital Video) recorded onto miniDV tapes, and (..for some backwards compatibility with Video-8 and Hi-8 mechanisms..) the same DV format recorded onto Sony's 8mm tapes.
DV Stream is that same kind of video (..which uses about 13 gigabytes of disc space for every hour's worth of video..) which one can send back to a DV camcorder, for example, in order to record an iMovie project back to tape (..using iMovie HD 6).
DV Stream is NOT useful if you want to prepare a video for streaming on the web, as it's too "bulky", and needs too much "bandwidth" (fast web connection) to carry it, as it's relatively huge compared with other formats. So for sending to the web, or for burning onto a DVD, or for most other uses, a more "compressed" video format is desirable, such as MPEG-2, MPEG-4, H.264 or one of the other dozens of video formats which -s-q-u-e-e-z-e- the material into a much smaller file size.
So 'DV Stream' is what you might call the 'native' video format used by camcorders which use tape, and which connect to iMovie via a FireWire cable.
Many (..most?..) recent amateur camcorders use a different video format: AVCHD ..that's much more compressed that the DV Stream format, so video takes up very little space on memory chips or small hard discs inside camcorders. It's a more 'compact' video format.
The trouble is, it's that much more compact because it has about only one-in-fifteen full frames of video. So when it's -e-x-p-a-n-d-e-d- during import into iMovie it produces much larger files sizes, because all those other "missing" 14 frames have to be rebuilt before the material can be edited.
So 'DV Stream' is the older, "fuller", 'larger' type of video, consisting of a full complement of proper video frames (30 per second in the USA, 25 per second in Europe) but taking far longer to send out via the web, and it's really only used for temporarily storing video on a hard disc, or for sending back to a tape-based camcorder.
Within iMovie, any AVCHD-format video or HDV-format video, is handled as 'Apple Intermediate Codec' format (..with all frames reinstated from the original compressed format). To burn to a normal DVD it needs to be converted to MPEG-2 format; for Blu-Ray discs it should be in MPEG-4/H.264 format. Other more compressed QuickTime formats can be used for display on the web.