Love Panna but not down with P2

stephenlnoe said:
Pinnacle and Avid (just now) can edit HDV in the raw form. That means HDV straight off of the camera can be diced and sent up to the satellite without a recompress. This is a tremendous advantage because the HDV remains in tact straight off of the camera. If the TV show was shot well then there only needs to be straight cuts and fades added and it's ready to broadcast.
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Not true though. If you change the GOP flow by even one frame, the entire program must be recompressed.

MPEG-2, as implemented in HDV, works in 15-frame groups, where every frame in a group is basically dependent on every other frame in that same group. If you trim a frame out, you'll disrupt the grouping of every GOP from that point thereafter. Frames will move into other groups, but they'll have no point of reference, so they'll need to recompress those groups. Trim one frame out, and you'll disrupt the grouping of every GOP from that point until the end of the program.

I guess if you were always able to edit on exactly 15-frame boundaries, you could maybe do a cuts-only edit, smush the pieces together, and retransmit without recompressing (not certain that's true, but it may be). But if you disrupt the flow by even one frame, you will have to recompress the entire program again (to the very lossy MPEG-2 compression).
 
Sorry Barry, Not true. LongGOP allows only the transitions or effects be rendered. The rest is left in tact. This has been the case since the DC1000. You might want to study up on LongGOP.
 
Do you have a source for this? I've read everything I could find on LongGOP and also SmartGOP on the Pinnacle site, and I haven't found anything yet that verifies that it can export a modified transport stream without recompressing it. I found nothing on the Pinnacle site to imply that it can somehow modify the length of a GOP within a transport stream without recompressing that GOP, and every one after it, upon output.

SmartGOP was a new invention with the DC1000 that allowed them to access any frame within an IBP GOP, obviously by decompressing and searching through the GOP -- and this is now employed by every native HDV editor. But that's just for finding frames, that has nothing to do with the necessity of recompressing every modified group.

What you're saying is, you could have an hour-long program, trim off the first frame, and then export without recompressing the entire timeline. I'm saying that AFAIK, that's not possible. Unless transport streams can provide for different-length GOPs within the same stream, it's simply impossible. I've searched google, pinnacle, canopus, Adam Wilt's site, Adam's articles in DV magazine, HDforIndies, Apple's site, Avid's site, and elsewhere and haven't found anything that says that it is. Obviously I'm very interested in this, if what you're saying is true it's quite revolutionary for MPEG editing. So I ask again, can you please provide a source for the info? It's late, I'm sick, it may be there and I just didn't see it, but I'd sure like to know.
 
StephenInoe, You cannot edit an MPEG without the problems that Barry mentions purely because most of the frames in an MPEG do not actually exist. They have to be 'created'.

Further to this, when you talk of broadcast, no matter which way you look at it, your MPEG from an HDV camera will still have to go through all the same compressions that all the other footage goes through. There's no getting away from it.
 
I realize this is not an engineering forum but rather a camera forum. Here are two sources for you:

http://www.tvtechnology.com/features/Focus-on-editing/f_Long_GOP_Editing.shtml
The above article will give you the basics.

and

http://www.amazon.com/exec/obidos/A...54874/sr=11-1/ref=sr_11_1/002-2946646-2892046

The latter is an authoratative book on HDTV and all of the codecs and editing techniques. You can pick it up at your local library or Borders.
You will not find anything on Pinnacles consumer site about this without going to the forum or working with the engineers.

good luck...
 
stephenlnoe said:
I realize this is not an engineering forum but rather a camera forum. Here are two sources for you:

http://www.tvtechnology.com/features/Focus-on-editing/f_Long_GOP_Editing.shtml
The above article will give you the basics.
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From the article:

It gets a bit more complex if you want to output your project as an MPEG-2 program or transport stream. During capture, any standard MPEG-2 encoder actually records to disk just I-frames, difference frames and motion vectors. The MPEG-2 decoder only generates B and P frames upon output, and these have to be reconstructed into a sequence that follows the strict requirements of a valid MPEG file.

To accomplish that, Pinnacle uses a proprietary technology called "MPEG Splicing" to make one new flat file that follows the rules of MPEG. On either side of a given edit, the Pinnacle splicer rebuilds the necessary number of frames to generate new I, B, and P frames around the cut point, if they are necessary to produce a valid GOP.

"In effect, we are generating one MPEG-2 file for the entirety of the project," McLean said. "Only the first shot within a sequence needs to start with an I-frame. Other shots can be generated from I, P and B frames, depending upon the amount of difference or 'temporal redundancy' between them. It's a bit of black magic, but that's how MPEG-2 gains its bit stream efficiency by creating a transport stream that, unlike I-frame only editing, does not have to encode all of the temporal redundancy between frames."
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Editor321 said:
I have to admit,

MiniDv is so easy and cost effective. Maybe if I had started using DVCPRO first, the adjustment would be easier.

But at this point, I would slit my wrist with the inconviences of P2 tech..having to stop or getting a "Card full Warning" every 8 min would drive me crazy. 8 min = $1,700 ($212 per min - ouch)

Just cant do it...Wouldnt be prudent (in my Bush Sr voice) Not even in the name of having a pro-format.

But in a few years, this may be a viable option with the specs Nathan mentioned (60 min for $100 bucks - recording on whatever that may be out at the time)
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Did Jan give an opinion about P2 card prices in 6 months? If we look at a revised "Moore's law", related to computers, we could surmise that capacity will double every 18 months. However, there are other factors:

If they can sell more P2 cards because the market is bigger, that could reduce prices.
There may be radically new technologies coming out in the next year that increase the capacity.

I'm not an expert at memory, but I assume the P2 cards need to have special technology so that they the system can write to them super-fast. I'm not sure what normal flash memory allows, for example.

-Jerry
 
You can buy flash cards, not too expensive that can handle 15Megs/sec

also You, don't want to be like all those people who bought SUN stock at $80, right before it plunged down to $4
 
Wiyum said:
You're doing your own math here...
You look at price per minute of P2 and you treat it as a one-time use format like tape, yeah, it seems out of hand. But it isn't a one-time use format.
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Huh, I didn't tape were one-time use, I guess I've been doing it wrong...
 
stephenlnoe said:
I realize this is not an engineering forum but rather a camera forum. Here are two sources for you:

http://www.tvtechnology.com/features/Focus-on-editing/f_Long_GOP_Editing.shtml
The above article will give you the basics.
Click to expand...
Thanks for the link, that's one that I hadn't found. However, I still don't see anything in there that invalidates what I've been saying. They do say that they generate a new MPEG-2 file. While they mention splicing, they also say a new GOP needs to be created around the edit, and the obvious implication is that if the GOP boundaries are disturbed, new GOPs will need to be created for that as well.

Adam Wilt wrote up an article on the state of HDV editing, and a quick glance reveals that with all the HDV solutions available you will indeed need to render an entire new MPEG2 file for output.
 
.. thats actually a bad thing. starting out in a compression scheme that was developed for final delivery of content only is not the way to go. i might take a car to drive to my hotel in hawaii when i get there, but i dont want to start out in a car.. ill take a plane. its designed to get me to the point where all i need is the final delivery step.

just like mpg2 wasnt designed to be an aquisition or post compression scheme. ..its not a desirable method to use at all. but as a final delivery format its great.
 
don't forget BetaSX and XDcam are both mpeg2, of course highbitrate versions.
i agree that "transmission grade" mpeg2 definitely is a joke as an aquisition format.
 
@Barry-The way it works is that if you make a cut or add an effect then only the FX and cuts are rendered to a new GOP. The rest of the content is left un-touched (GOP wise). It is brilliant in it's design but it is not a new concept. It was done in hardware on the DC2000, and you were right in calling it smartGOP. In those days there were bugs but people were willing to live with them because of the stunning quality FX.

Now it is done completely in software. It has been brought along nicely by Pinnacle with their superb HDV codec.
 
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