[Graeme Nattress]

Comparing HDCAM and DVCproHD to 4:4:4 uncompressed HD (all 1080) I came up with the following figures:

HDCAM is 135mbps, which is a 11:1 compression over fully uncompressed.
DVCproHD is 100mbps, which is a 14:1 compression over fully uncompressed.

However,

Of the 6220800 pixels across the 3 components of fully uncompressed,

HDCAM records 2592000 of them, or about 42% of them.
DVCproHD records 2764800 of them, or about 45% of them.

But if you look at the ratio between recorded luma pixels and recorded chroma pixels,

HD 4:4:4 YCbCr for every 1 luma pixel there are 2 chroma pixels.
HDCAM for every 1 luma pixel there are 0.66 chroma pixels.
DVCproHD for every 1 luma pixel there are 1 chroma pixels.

So yes, HDCAM is less compressed than DVCproHD, but it also records less of the pixels from the uncompressed image, although it does this by recording more luma resolutio and a lot less chroma resolution. We can now look at the number of bits per pixel that is used to compress the image:

HDCAM uses 1.82 bits per pixel and
DVCproHD uses 1.26 bits per pixel

Because both formats balance the compression parameters very differently, especially the lower spatial luma resolution recorded by DVCProHD, it’s very hard to compare them directly just looking at the figures. A lower spatial resolution filtered down from the original 1920 to 1280 should be easier to compress because a) it’s smaller and b) will have a higher degree of super-sampling and hence have less sharp edges which cause DCT codecs bother. Also, the lower spatial resolution of DVCproHD might correlate better to the limitations of lens resolution on the camera, and this will especially be the case as we get more 1/3″ chip cameras using the DVCproHD codec.

Hope this is enlightening and if anyone has more facts or figures to add, that’d be great.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

Which is often necessary for the volume levels! 🙂

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

But can you dry your hair with the fans? And also, don’t forget that the Xraid doubles as a weight lifting exercise. That 100lbs really gets your blood pumping as you move it into position.

Indeed, I was impressed with what I saw of the Medea at NAB, but I really like the aluminium look, and the robustness of the Xraid.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

True, but you’re forgetting the shear sexyness of the Xserve RAID! And all the flashing lights.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

But FCP5 does indeed decompress HDV in real time and also allows full native editing of the MPEG2.

Sure, you can’t compare codecs directly, but the current figure for HDV type MPEG2 efficiency over that of a DV type codec is about 2.5 times. Given that it’s compressing 4.5 times as much data per second, you can see where that leaves us….

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

The Decklink HDLink is excellent for monitoring HD, although 720p doesn’t fill a 23″ screen, but 1080 does lovely. Due to it’s firmware upgradeability, new features just keep getting added to it. Nice.

For hard drives – forget firewire and just get a big Xserve RAID and forget about it. Really.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

HDV is highly compressed and editing it as uncompressed does not improve that quality one little bit, and in reality, you’re trading less processing power needed for more hard drive size and speed needed. You’re not altering the absolute quality of the video one little bit. This may be advantageous if you render the final output uncompressed to go out over SDI to a high end HD deck like HDCAM SR or D-5, or even DVCproHD or HDCAM, but will be of no benefit for going back out to HDV, and probably marginal benefit at best for making a HD-DVD or H.264 DVD.

As for keying – HDV is 4:2:0 and hence has as bad as color sampling as PAL DV, and in numerical terms, the same resolution loss altogether as NTSC DV, and as it’s even more highly compressed, will in all likelyhood pull a worse key. However, due to it’s higher resolution, the artifacts from the key will be smaller, but they’ll still be there. Even HDCAM is not the easiest format to pull a key from – as hard as DV in my experience.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

I’m working on it!!

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

See the discussions in the forum for more options with regards to record time.

Graeme

– http://www.nattress.com – Film Effects for FCP

[Graeme Nattress]

The HVX200 sounds nice and flexible, but until we see the pictures from it….. Anyway, if you want to know more, we have a forum over here: https://www.creativecow.net/forum/view_posts.php?forumid=193 for it.

Graeme

– http://www.nattress.com – Film Effects for FCP