DVCPRO HD at 40 Mbs?

B

Bob Diesso

Active member
This statement by Tosh Bilowski on Panasonic's defperception site has me confused:

"If you are working with the P2 card in 720P at 24 frames, the P2 card can be set to record just the 24 flagged frames(works differently on the 1080I/24P). At 720P/24, it is the same thing as the VariCam but the flagged frames being saved constitute 24/60ths of the entire data rate, or roughly a little more than 1/3 or 100Mbs. It comes out at 40Mbs, and thus it takes up less real estate than DVCPRO50." "Tosh" is Panasonic's voice, so this post must be true.

Panasonic themselves have claimed HDV is "bandwidth starved".
An important part of the DVCPRO HD vision for me, at least, was superior HD quality at 100 Mbs, as opposed to HDV's 25. Even at MPEG's claimed 4x efficiency, DVCPRO at 100 Mbs still seemed the clearly superior idea.

So, if HDV is "bandwidth starved" at 25 Mbs, what does that make DVCPRO HD at 40 Mbs?

I really want to believe in HVX, but there are too many conflicting spins as Panasonic gradually takes the wraps off of HVX.
 
Its 40 mbs when you shoot 24 fps in 720

HDV is only 19mbs in 720 and thats for 30 frames.

If you shoot 1080P with the HVX its 100 mbs vs the HDVs 25mbs
 
100Mbps is at 720p60. Obviously, there is no need to capture all 60 frames when shooting 24 on a P2 card like they do on DVCProHD tape. But the bitrate of each frame is the same, hence 40Mbps at 24fps.

Take for examble a single frame:

At 60fps, each frame is 1.66Mb (approx 208KB per frame) for a bitrate of 100Mbps; so 24fps at 1.66Mb each frame comes out to 40Mbps. Nothing is lost. Plus, you can do variable frame rate up to 60 discreet frames per second, and you have 4:2:2.

Now consider HDV 720p24 (JVC), roughly and loosely speaking (due to MPEG2), each frame is 0.79Mb (approx 100KB per frame) for a bit rate of 19Mbps. That's half the bit rate of 720p24 of the HVX. Of course, if HDV was able to do 60p, a single frame would weigh 0.32Kb (or 40KB per frame). So apple for apple, HDV's "720p60" is 40KB per frame vs HVX's true 720p60 measuring at 208KB per frame. There is no contest!

If that's not enough, 1080i60 for HDV is 25Mbps, and 1080i60 of DVCProHD is 100Mps. We're talking 4 times more info.
 
Does the firestore drive accept the full 100mbps of the hd video< someone told me
(a JVC RESeller :) ) that the firestore fs 4 hd could'nt handle or accept anything over 25mbps. I think the p2 cards are a rip off, but if I know I can do an hour or more storage of 100mbps hd video on the firstore, I'M sold .. AM I way off on this??????

Team Ramrod2
 
The FireStore FS4 cannot handle the DVCPRO-HD data rate, no. That's why they're introducing a new FS-100 which is designed specifically to work with the HVX and which will easily handle the full 100mbps data stream.

You will be able to do at least 100 minutes of recording on the HVX Firestore combo.
 
Yes, DVCproHD is very compressed, but it's still more lightly and more edit friendly compressed than HDV. It's not that DVCproHD is the best codec around, just that it's better than HDV.

Graeme
 
DVCPROHD high compressed...

DVCPROHD high compressed...

Why do so many people keeping saying that DVCPROHD is 'very' or 'highly' compressed. Isn't it only around 3.3 to 1? I may be wrong that's why I asked. While we are at it what's HDCAMs compression?
 
Here's the figures I worked out a while back. They're approx, but give the right sort of ratios:

Comparing HDV, HDCAM and DVCProHD to fully uncompressed 8bit 1920x1080 4:4:4 HD, the ratios are as follows:

Fully Uncompressed 1:1 = 1424Mb/s
HDCAM 10:1 = 135Mb/s
DVCproHD 14:1 = 100Mb/s
HDV 56:1 = 25Mb/s

The above table makes sense as each format is compared to the same thing.

Comparing each format to it's uncompressed native dimensions and chroma sampling, ie:

HDCAM to 1440x1080 3:1:1 (593Mb/s), gives 4.4:1
DVCproHD to 1280x1080 4:2:2 (633Mb/s), gives 6.3:1
HDV to 1440x1080 4:2:0 (534Mb/s), gives 21.3:1

The HDV codec, is probably around 1.5 to 2.5 times as efficient as DVCproHD / HDCAM codec, but even so, you can see it trails quite significantly.

Graeme
 
Here's the figures I worked out a while back. They're approx, but give the right sort of ratios:

Comparing HDV, HDCAM and DVCProHD to fully uncompressed 8bit 1920x1080 4:4:4 HD, the ratios are as follows:

Fully Uncompressed 1:1 = 1424Mb/s
HDCAM 10:1 = 135Mb/s
DVCproHD 14:1 = 100Mb/s
HDV 56:1 = 25Mb/s

The above table makes sense as each format is compared to the same thing.

Comparing each format to it's uncompressed native dimensions and chroma sampling, ie:

HDCAM to 1440x1080 3:1:1 (593Mb/s), gives 4.4:1
DVCproHD to 1280x1080 4:2:2 (633Mb/s), gives 6.3:1
HDV to 1440x1080 4:2:0 (534Mb/s), gives 21.3:1

The HDV codec, is probably around 1.5 to 2.5 times as efficient as DVCproHD / HDCAM codec, but even so, you can see it trails quite significantly.

Graeme
Click to expand...





Hows that compared to "PAL" DVCPROHD

100mbs 25fps vs 135mb 30 fps of the HDCAM
 
I don't know the full details of the PAL DVCProHD1080i codec, but really, it's not a fair comparison to compare 25fps with 30fps.

Graeme
 
that depends on if the cinealta shoot 24P the same way as the Varicam shoot 24P with redundant frames?

Is cinealta 24P 135 mbs or 108 mbs?
 
Cinealta is around 135-140mbps, and I don't think it changes for 24p as it puts it as 48i in a PAL stream, os something similar, I think. DVCProHDPAL is also 1440x1080 unlike the NTSC version, so I think it's as compressed as NTSC, but just a different balance of compressions.

Graeme
 
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