Who is airing straight HDV?
by randall m
on
Jun 27, 2007 at 2:09:37 pm
Hi.
Does anyone know what networks (cablecast/broadcast) are currently airing HDV? What delivery method is being used, meaning tape or mpeg2 multiplex file for their servers?
Also, I'm wondering how the footage holds up being composited with graphics, keys, like photoshop files, etc.
Re: Who is airing straight HDV? by epontius on Jun 27, 2007 at 4:30:28 pm
I would doubt anyone is. Broadcast is glacier slow to adopting new formats. HDV because of its long GOP compression and multiple flavors (720p, 1080i, etc...) from different manufacturers all doing their own thing...probably to much of a hassle.
Most likely they would require HD material on HDcam or DVCproHD tape.
I think some are using very high bitrate MPEG2 for libraries and such.
As for compositing, etc... again because of the compression used in HDV, most folks convert the MPEG2 to a different codec to use in compositing.
As for green screen, it is plagued with problems similar if not worse than DV...again due to the compression and reduction of color by subsampling...less color information to work with, the harder it is to key. It is possible to do, and certainly good keys have been pulled, just important to plan and do a very precise job of lighting to be able to minimize the problems.
Re: Who is airing straight HDV? by Randall M on Jun 28, 2007 at 1:02:32 am
Erik,
Thank you for your thoughtful insight. I've been discussing this topic with colleagues today and the conclusion was that simple keys or small graphics do not seem to be a problem, and they echoed your points- that green screen is very problematic and that good lighting is essential.
You mentioned that most folks would convert the HDV to a different codec for compositing, could you elaborate? Is this to mean they upconvert the HDV in a new timeline with a higher res codec, or that they capture the footage with a different codec using a capture card or something like the yet to be released AJA IoHD box?
As a footnote, I'm due to produce a few shows for RFD-TV (Rural Free Delivery) that is carried on Dish Network. In November they are scheduled to start their own HD channel (RFD-HD). I called the program director yesterday and confirmed that they will accept HDV tape as a final product. Perhaps the glacier begins to move with DBS channels like these.
Re: Who is airing straight HDV? by epontius on Jun 28, 2007 at 1:44:42 am
Sure. HDV is actually a stream of MPEG-2 "long GOP" video, meaning that the HD video is compressed to a data rate similar to DV video (25Mb/s). Long GOP is referring to the method in which it is compressed. "GOP" stands for Group of Pictures. In a GOP there are I-frames, B-Frames and P-frames. I-frames are the only frames that actually contain all the information to make up a single complete frame of video. The B and P frames contain only changes that occur to areas in the I-frame or references to other frames.
When captured in an NLE as HDV (mpeg-2 long GOP) the NLE, has to assemble (decode) complete frames on the fly as you edit and playback through the footage...a process that can be computationally intensive for a computer. Once the footage is edited you are limited as to what you can do with it. In some cases if you want to export the edited footage from the NLE back to HDV tape, you need to re-compress or transcode the footage to an MPEG-2 Transport Stream and then export this to a deck.
With compositing, you run into similar problems. The compositing application would have to decode the mpeg video to be able to use it properly, and then exporting HDV may also be difficult or impossible.
The more and more you re-compress compressed footage the more the quality will degrade. And this is a reason that many choose to transcode or export the HDV material to an uncompressed or "lossless" codec in order to work with it.
Some editors may choose to capture HDV to save space, perhaps even editing it in HDV for the same reasons. If they have the space the captured HDV can be converted to a different codec (like Avid's DNxHD codec) that is high quality and faster to work with in the NLE since it doesn't have the added overhead of decoding the MPEG video.
In some cases, as is with the Sony HVR-1500 HDV deck, the HD signal can be captured over HD-SDI directly to a codec suitable for editing (like DNxHD) but at the cost of eating up a lot of disc space.
When it comes time to finish or add effects the entire sequence or clips may be transcoded or exported to an uncompressed or other high quality codec that uses whole frames of video for each frame in the video. The same would then happen when exporting out of the compositing application. This exported video could then be imported back into the NLE to then edit into the sequence or export to tape. In order to export back to HDV tape the sequence has to be converted back to an MPEG2 transport stream and sent to the deck.
Also, if RFD-TV is accepting HDV tape as a delivery you will need to get specifics as to which flavors of HDV they will accept (1080i, 720p, etc..). To make matters worse, not all HDV decks will be able to play and stream tapes recorded on other manufacturer's equipment.
HDV is a good cheap hd format but has its headaches as a tradeoff. Other formats like HDcam and DVCProHD don't have quite the same quirks but are more expensive formats to work in.
Re: Who is airing straight HDV? by Steven L. Gotz on Jun 28, 2007 at 3:07:19 am
I would like to add my two cents on the issue of keying HDV. I spent the first couple of days this week doing some green screen work for some tutorials using my Sony FX1. We shot some perfectly lit, wonderful footage that we were very proud of. I really liked how we lit the screen but didn't have it blown out. I have never used some of those features on my camera before. Very educational. I had never used it in a real studio before.
But since this was for tutorials, we then shot without the backlight to show what the problems would be. Green fringing etc. Then we began to turn off lights one by one. We figured we would just go through the footage to find the best key, a medium decent key, and a really bad key.
Well, it wasn't that easy. Using Keylight, we darn near had to turn off all the lights on the paper green screen to get a bad key. Heck, we got a good key in Premiere Pro of all things (with the good footage of course).
I don't know what to tell you, but the FX1 footage keyed out so well, we are going to have a tough time showing a bad key. I just wish we could do it again with blue to see the difference. I imagine that would be tougher to key.
So, don't be afraid of the keying out of HDV until you try it yourself.
Re: Who is airing straight HDV? by Randall M on Jun 28, 2007 at 3:51:57 am
Erik, Steven
Thank you both for the great info. Erik, I noticed you are in my geographic region. Let me know if you are freelance or have your own company.
I will check back with RFD-TV to request specific submission guidelines once they have them for the new HD channel. He admitted that they already have a handful of shows shot on HD but that the producers down-convert them to SD for submittal on the SD channel (of course). They don't do any conversions themselves.
I already know they accept DVCPro format for SD, so perhaps a natural step may be DVCProHD for the new channel. I suppose I could export to a lossless codec and then send out to a DVCProHD machine for the end product. I'm planning to stay at 1080i with the least compression possible beyond what already happens when it gets crunched to that small tape.
Re: Who is airing straight HDV? by Michael G on Jun 28, 2007 at 4:07:24 am
Here in Australia I have had HD programs broadcast from mostly HDV originated material. The trick however is to do all the post using either uncompressed or a codec like ProRes422 or the Avid lossless codecs.
I ingest via a Canon XL H1 going HD SDI into a FCP (Decklink) capturing uncompressed 10 bit 422. All grading & graphics are done in this uncompressed timeline and then the master goes out to an HDCam (1080 50i).
Broadcasters will accept this as HD (although some like Discovery won't accept more than a fixed % of HDV originated. This I think is an ignorant approach but probably reflects disappointment with material that has been entirely edited and rendered in HDV codec.
Well shot material, especially avoiding weak areas of many handycam lenses, using a TRIPOD!, and LIGHTING! and strict care on focus can make for very impressive HD results. Is it as good as HDCam shot on a prime lens? Usually not, but it can be better than poorly shot HDCam.
Re: Who is airing straight HDV? by Randall M on Jun 28, 2007 at 5:07:12 pm
Michael,
Thank you for sharing your workflow. I like the sound of that progression and it seems very attentive to achieving the best results possible. What version of FCP are you working with... 5.1.4? or 6?
ProRes 4.2.2 sounds good to me, but with all the discussion lately on the cow about beefy machine requirements has me a bit confused, like if I intend to edit with HDV material in the ProRes 4.2.2 codec- perhaps using the AJA IoHD box- I gather my Mac Pro needs as much ram as I can afford. Or perhaps I'm totally off-base. I've listened to that NAB all things Apple podcast a few times now and I'm all mixed up. ha ha.
I agree with your sentiments about Discovery- and absolutely their percentage requirement is in response to discouraging submittal of... well how should I say this? Stuff that looks like crap. And also true, just because it's on HD doesn't make it great material. I always say- you still have to know how to tell a story and attention to good production values is icing on the cake.
Thanks again for your insight. Worthy of my archive.
Randall
Re: Who is airing straight HDV? by Tim Wilson on Jun 29, 2007 at 10:34:09 am
It might have been hard to find in that mountain of words in the two ProRes articles, but the most frequently recommended workflow in your situation is editing native HDV in a ProRes timeline.
Some highly respected folks recommend this workflow even if you have other options, including direct capture to ProRes.
Re: Who is airing straight HDV? by epontius on Jun 28, 2007 at 5:03:10 am
Erik, I noticed you are in my geographic region. Let me know if you are freelance or have your own company.
neither. I work full time doing video production, editing, compositing and compression for a large global technology company...so I'm just another cog in the wheel. I do everything from training videos, event roll-ins, funny videos for department events, talking heads, broadcast b-roll, whatever gets thrown my way. Usually with no budget and short runway...really keeps you on your toes.
We shoot everything HDV or HDcam, edit mostly SD with a small amount edited HD since the majority is for SD output to betacam for broadcast or compressed to windows media, flash or streamed over the web. As the demand for HD delivery increases I hope to do a lot more in completely HD workflow.
Re: Cog with benefits. by Randall M on Jun 28, 2007 at 5:19:24 pm
Erik,
Ahh, the silicon hills.
Well, hopefully you are a cog in the wheel with a good set of benefits. I worked at a technology consortium here in Austin for about 10 years before all the internal video opportunities seemed to dry up and the order of the day was... "Hey can you take our photo? So and so co-worker is leaving." As was everyone at that place. ha ha. I shouldn't laugh. It's actually very sad, but that's another story.
At least it sounds like you have a budget to work with and your company values the power of video as a communication tool. I finally started my own production company a year ago and have been busy ever since. Thankfully.
Re: Who is airing straight HDV? by Nick Righton on Jul 6, 2007 at 5:43:34 am
I have heard of a workflow using Miranda's HDV to ASI conversion, but have not used it myself. It looks like it will do what you want. http://www.miranda.com/product.php?i=342
