Canon Survey slants toward HD

[Rob Lohman]

Really? I thought it had a 1 frame GOP. Hmmm, someone has
some link to actual technical information on this? If that's true
then I'm not liking it one bit...

[Aaron Koolen]

Yeah then it comes back to my original question I guess. Where can we get info about this?

With Dv25 being 25MBits, at 1 gop that would be 1Mbit per frame for PAL, which is 131k roughly. Now that's not much bandwidth for a 720x576 frame to go into and it's about 25x more than an uncompressed 24bit frame. So, the mpeg would have to get 25:1 compression. Can it get that and still look good enough for indy filmmakers?

Maybe my understanding is buggered but it seems like it's going to suck if there isn't 1 frame GoPs.

I'm going to keep searching for info on this as I would have thought that the big companies involved in HDV would have wanted to increase the quality of image aquisition for independent filmmakers so that they make more films, rather than lower it or keep it the same. Maybe I'm wrong and maybe by making this HDV standard they're hoping it will force more people to consider higher end cameras once they've had a taste of some form of HD....Wouldn't have thought so though.


Aaron

[Daymon Hoffman]

I cant find any links atm but i think you'll find its a 6frame GOP.

I feel that its the MPEG2 over compression for the HD10 that is fairly big show stopper. Plus MPEG2 being lossy. If they were all I frames and higher bitrates (say 25 or 30mb/s) then it'd be most likely workable.

But i'm a seeker of quality myself and to me MPEG2 is a delivery codec not a master/capture one and i really am not keen that HDV has gone that way. Especially when we are on the brink of MUCH better compression codecs that are much easiler edited (MPEG4 varients! XviD/WM9 etc etc).

Just imagine using WMV9 (yeah M$ i'm not keen on but they have a decen codec just teh same) with 720p50/60 in a HD Cam. They could use miniDV tapes as with the HD10. But instead of an ~18mb/s MPEg2 stream they could have a 15mb/s WM9/MPEG4 stream with all K frames (or which ever ones they are, you get my point) just as with DV. Plus 15mb/s bitrate for newer codecs is actaully over saturation bitrate which is what we need for quality. Plus you could fit more minutes on your miniDV tape....

So its stumped me why JVC really went that way even tho its "workable" its really not very future conscious AFAIC.

/end rant :)

[Rob Lohman]

Well, according to this PDF on the JY-HD10 from the JVC Pro site,
the following is the case:

HD, MPEG-2 TS(GOP=6)
Recording mode: 720/30p(16:9)

SD, MPEG-2 TS(GOP=12)
Recording mode: 480/60p(16:9)

So it seems to be either an 6 or 12 GOP structure, depending on
the mode you selected. I almost can't believe it. This is a real
let down. I'm hoping very much that the official HDV standard
has a 1 GOP structure.

That lower resolution mode is running at 60 progressive frames
a second it seems. That would be interesting for slow motion
work though.