On Sat, 20 Sep 2003, Richard Ellis wrote:

> On Thu, Sep 18, 2003 at 08:45:45PM -0700, Steven M. Schultz wrote:
> > 
> > Is this for protection against a drive failure?    DV (or MJPEG)
> > capture's data rate requirements are extremely modest (in the
> > ~3.5MB/s range - even a notebook drive can sustain that without
> 
> On my system, running the newest DC10+ driver (0.9.something),
> capturing at 640x480 frame size, and a driver quality setting of 75,

        640x480?  Thought fullframe NTSC was 704x480 - or is the DC10
        using square pixels instead of the Rec.601 10:11 pixels?  DV's
        weird - it gets an extra 8 pixels on each side for 720x480.

> results in a sustained average of 7.5MB/s of data being written to
> disk.  I only see data rates in the sub 3.5MB/s range for 320x480
> frames, with a driver quality factor of 50, which gives about
> 2.5MB/s.
> 
        Ah, that's what I was curious about - thanks for the info!

        I was under the impression that the MJPEG cards had similar
        data rates/compression as DV did - and that's only 25Mb/s
        (~3.5MB/s) for full quality (no choice in the matter ;)).

> Capturing full frame (well, a DC10+'s idea of full frame) and at a
> driver quality setting of 100 results in pretty much dead on a
> sustained average of 10-11MB/s of disk write bandwidth.

        Yikes - and yes, I can see using a raid-0 setup for that.
        Back when I was messing around with the Bt878 based capture
        setup the fullframe IYUV (4:2:0) rate was around 12-13MB/s.
        3 spliced 10k SCSI drives could handle it but it was a nuisance
        (and the quality was adequate at best).   DV's so much more
        convenient :)
        
        Thanks for the info.

        Steven Schultz



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