HDV Bottle Neck

jkrepner wrote on 6/9/2005, 7:23 AM
Where does the bottleneck occur?

Do we need extremely fast processors to keep up with the native HDV codec?
Do we need fast SATA or SCSI RAID arrays to maintain the throughput of the larger intermediate files?

It seems to me that if we convert the native HDV files to larger intermediate files, hard drive speed becomes more important than processor power. Right, I mean it’s just a big AVI?

5 years ago I was running a VT2 (Video Toaster 2) on a Pentium 3 450mhz machine capturing huge uncompressed files and working with those large files in Speed Razor with no problem. The VT2 didn’t do any hardware acceleration; it was just an I/O board like the Blackmagic gear. I can't see why a Pentium 4 3.0 with HT can't do the job if the drives are fast enough. Perhaps 4 10K RPM SATA drives set as RAID 0, would be fast enough for easy editing of intermediate HD files?


Comments

Spot|DSE wrote on 6/9/2005, 7:47 AM
First, there really isn't an HDV codec, this term has started creeping up a lot. It's just MPEG-2, only a higher bitrate than DVD.
A faster, 3.2 or so GHz computer can generally manage the DI streams if they're in a wavelet compression such as CineForm's codec.
Hard drive speed is important, but the file is also much larger in content (frame) than SD, so a lot more proc power is needed. Plus (believe it or not) compressed formats take a lot more horsepower than uncompressed formats due to the decode.
Remember, avi is just a container, there can be several types of codecs in that container. For instance, CineForm is an avi, but it's a wavelet, basically a 2GOP mpeg in there.
This is what the CineForm is for, to make it easier to edit/process so the processor isn't working so hard, leaving room for the NLE to work with.
I wasn't aware that VT2 wasn't hardware accelerated? Also, you were using SCSI drives, or should have been. To my knowledge NewTek has never endorsed IDE, but I may be mistaken.
jkrepner wrote on 6/9/2005, 8:05 AM
Right, now it makes more sense, thanks. The frame is larger, so there is more to it than just physical file size.

Oh to answer the question; they were SCSI stripped as RAID 0. The reason why the VT2 did work on such slow machines is exactly what you said, it wasn't compressing/decompressing anything, so it was up to the drives to pass on the info, as is, thru the SDI. In-sync was way ahead of the curve with Razor in that they knew the future was with software solutions that used computer power, not specialized hardware (like the Matrox Digisuite and Targa solutions available back then).

As a matter of fact, the Video Toaster 2 and In-sync's Speed Razor is a lot like the Blackmagic and Vegas setup today.

So perhaps a Blackmagic HD card would be the way to go? Can one convert the HDV MPEG-2 into uncompressed HD? I couldn't even imagine that file size...

Thanks. Jeff