OT: Farss and DVCProHD

kairosmatt wrote on 8/1/2008, 6:03 AM

Bob-
I was late coming into the vidcap thread, but at some point you stated this in reference to HDV:

It's only better than 1 solid state format, AVCHD and arguably better than DVCPro HD.

How would you argue its better than DVCProHD? Just curious, I've never read anything that put HDV as the better codec. From what I've read, it arguable about which is better between DVCPRO and the EX1's MPEG codec.

kairosmatt

Comments

farss wrote on 8/1/2008, 7:46 AM

I think the key word there is "arguably". DVCPro HD or as it is sometimes called DVCPro 100 uses more spatial compression than HDV. HDV is 1440x1080 whereas DVCPro HD is 1280x1080. On the other hand HDV uses temporal compression to fit the video and audio into a 25Mb/s stream compared to DVCPro's 100MB/sec stream. Also HDV uses 4:2:0 sampling compared to DVCPro's 4:2:2 however from what I can glean that 4:2:2 sampling can be a bit misleading as the number of actual chroma samples is not as many as you would think and most certainly not on the HVX200, in fact I recall somone doing the maths and proving that HDV had more chroma samples than DVCPro HD from the HVX200. On the other hand though I *think* that the DCT compression used in DVCPro is higher than that used in HDV.

To further muddy the waters mostly HD SDI uses 1920x1080 which means in broadcast DVCPro HD is being upscaled and downscaled. How really important that is I don't know but it was a factor a broadcast bod mentioned to me. Not that HDV would fare any better but no one ever claims HDV as a broadcast format in the sense that you'd feed in through switchers and encode back to HDV.

As you can see it's hard to know exactly which is the better and more often than not the discussion is more about the camera than the codec. Certainly the 'HDV' encoding done in the EX1 is better than the earlier HDV cameras and the resultant quality of DVCPro HD from the HVX200 is way more about the signal going into the encoder than the codec itself.

Also another consideration is that DVCPro HD is way easier to encode and decode than HDV. It's basically 4 DV codecs bolted together and could almost be called HD DV. The other thing I have to give Panny is DVCPro 25,50 and 100 use the same tape run at faster speeds. It's therefore possible to get VCRs that play and record multiple formats.

To me though it all becomes a bit of a silly argument. DVCPro is very old and low tech by todays standards. HDV is more advanced but still it too might fade away thanks to more advanced codecs that are feasible due to faster silicon. Panny are already going to AVC Intra and Sony must surely soon have a decent high end camera using a wavelet codec sometime soon.

Certainly one aspect to all this that I don't think is arguable even though it was always wheeled out as though it was chiselled in stone is that more compression isn't always bad. If better compression schemes get more of the original image into the same or even less bandwidth that is a good thing.

And how much does all that really matter, not much as I've come to realise. What's in however many pixels you've got is way more important. Lenses, lighting and a skilled DP have way more impact. Dynamic range is also much more important in my opinion than a few pixels or compression if you wanted to get into a technical discussion and both HDV and DVCPro HD are only 8 bit.

Bob.

GlennChan wrote on 8/1/2008, 8:45 AM

Might be of an interest: a comparison between the HVX200 (DVCPRO HD) and the JVC HD100 (HDV):
http://www.bluesky-web.com/HDVHVX.htm

It looks like these two particular cameras key about the same. Neither camera is ideal for keying (e.g. you can see in the video that the key flickers... likely due to noise in the source), but people do manage to get good results with the cameras. I think the music video Poets of the Fall was shot on HDV (the JVC I think)... check it out, it's an awesome video.

The DVCPRO HD's 4:2:2 is a misleading numbering scheme IMO... the format records 1280x1080 luma samples and 640x1080 chroma samples. HDV is 1440x1080 for luma and 720x540 chroma samples. If you record with interlaced chroma encoding, then the vertical performance of HDV is not as good... I would simply treat it as if the chroma performance vertically was cut in half.

If you take a look at the Vegas 6/7 sample projects (can't remember, probably 6), it contains a Cineform clip where you can see chroma artifacts on the flower shots (if you know what to look for). The chroma skips every other line... so it kind of looks like the venetian blind effect with interlaced footage except a lot more subtle. On no-movement shots with highly saturated colors you would see this.

2- In rare situations, certain things can break a HDV encoder. But I believe it depends on which encoder you're looking at. I've seen some shots where people break the Z1. (I don't think the JVC does it???)

3- Bottom line... I would just look at the camera system as a whole. A lot of it depends on the implementation of the system (e.g. what resolution the CCDs are)... and the implementation varies widely.

And talent matters even more of course, as Bob mentions. :)

kairosmatt wrote on 8/1/2008, 11:19 AM

Thanks for responding guys. I totally agree that talent and experience matters more, but for some reason I find this topic very interesting-even if it is a bit 'muddy'

That said, I know a lot people knock the HVX for its low density CCDs, but man I love the image-and at the end of the day my subjective perspective isn't really bothered whether its DVCPro, HDV or AVCHD!

I will say that it does play back faster than HDV or AVCHD on the timeline, so its more pleasurable to edit.

cheers,
kairosmatt