Anybody knows why 25p clips shot with the PD1 are 32 bit - likely 4 channels?

Seems to be there's an alpha channel included but what sense makes an alpha channel when shooting with the PD1?

Marco

HDV is 8-bit. Are you changing codec?

No, 32 Bit is in the native stream. It's the original .m2t-stream coming directy out of the PD1. HDV is 8 bit, yes. Per channel. So it is 24 bit for YUV. But why is it 32 Bit in the PD1 streams? Looks like an alpha channel or somewhat else.

Marco

A Note About 8bit vs 10bit:
This describes the number of levels per color channel. Most cameras use 8bit compression technology such as DV, HDV, and DVCPRO-HD, for representing up to 256 levels in each of the color primaries R,G,B or Y,U,V. Whereas 10bit formats are more commonly used in high-end film and broadcast applications or uncompressed material delivered across HD-SDI.

Your PC is displaying it out as 32bit video because that is what your display is set to but that has no barring on the video colour space. Your graphics display can be set to 16/24/32 bit. Video codec info is stated as 8-bit/10-bit/16-bit. There exceptions, but those are the basics.
So the actual HDV video will never higher than 8-bit because that is the format recorded to tape.

Maybe I still did explain it the wrong way. I know about what 8 bit or what 10 bit video means as I am a professional editor for almost 15 years now.

What I talk about is in what way my NLE - Vegas - displays the video properties. It displays any dv video file as 24 bit, because there are three channels of colors, each one 8 bit. If I render an uncompressed AVI it also displays its property as 24 bit if I did not render an alpha channel included in that uncompressed file. If I render an uncompressed avi with an alpha channel included it displays 32 bit because here I have three channels of color information and that one additional channel with transparency information - 4 channel, each 8 bit is 32 bit in the end.

And this is what it looks like when Vegas displays the PD1 .m2t-files. In this case it definetely has nothing to do with my graphic card display. If I have dv and PD1 .m2t files mixed in one project the dv files are displayed as 24 bits - because of it is 3 channels of each 8 bit color information - and .m2t-files are displayed as 32 bits.

So it's not about whether there is more than 8 bit each channnel, but whether maybe there is more than 3 channels stored like it is done in any video file which contains 3 color channels plus an additional alpha channel.

Marco

The PD1 is not HDV but a special SD MPEG2 stream only. So maybe somebody can help him?

The PD1 records in HDV format.

Signal processing is internally done in a high resolution format but PD1 always records at 720x576. It's not HDV. It's kind of PAL SD in an MPEG transport stream. At least this is what any PD1 user I know, including me, gets out of the recorded tapes via firewire.
Unless there is any unknown trick to get more than 720x576 recorded. If so, please let me know. I'd really like to get HDV - 720p - out of the PD1.
Or do you mean that's right it - HDV recorded but only SD output?

Marco

HDV has SD modes. Your right that it only has two modes 576p25 (downsampled 720p) and 576p50, but they are both recorded in HDV format.

In your opinion how do the two modes compare, meaning is there a strong visual differance between the two besides frame rate?

But which hdv format then ;) How does the SD modes record compared to the 720p, 720p24, 720/36 mode compared to the 1080p modes.

I think Marco just wants to find out what is happening at his editor end (one possibility is that the data is repacked into another transport stream for transport of firewire and there is no advantage, do some testing on the data and pixels, and ask JVC and your editing software manufacturer).

>> In your opinion how do the two modes compare, meaning is there a strong visual differance between the two besides frame rate?

Yes, the 25p version looks sharper.

>> HDV has SD modes.

Do you have resources for this info? I never heard of SD HDV modes. None of the HDV definitions I saw include a SD format. There's "only" 720p and 1080i, each with several frame rates.
This might be the reason the PD1 may not be called a HDV camera. JVC named it "HiRes" instead, though HiRes isn't what could be used the digital way out of the camera here.

>> I think Marco just wants to find out what is happening at his editor end

Yes, there might be several possibilities.
Maybe there is just a kind of additional "blank" channel sent with the stream. Maybe the NLE simply analyses something wrong (though there are some other tools which also analyses 4x8 Bit).
But as the PD1 records at 18 MBit/sec - which is rather high for just an SD stream - maybe there actually is another channel with extra infos stored in addition to the YUV channels.
I can't get out any more for now. Yes, I maybe should contact JVC, but I doubt they'll give too much information about the PD1. ;)

Marco

The HD1/10 both have the SD modes as well as the new HD100. 480p60 is the NTSC version. They are captured at 60fps and a GOP of 12, compared to the 720p mose that uses a GOP of 6 but at half the frame rate. The recording format that these cams use is HDV. As opposed to DV which was a set dimentional codec, depending on your region (SD or PAL) HDV includes multiple frame sizes and frame rates. Any resource that defines the HDV codec will give you all the details.

If you look at this page from Cineform you can see a quick rundown of all the HDV resolution/frame rates. One should notice that they do list 720p24 which is not officially supported but is contained within the 720p60 spec.

http://www.cineform.com/products/AspectHDPPro.htm#AHD_Features

Maybe this is a misunderstanding. I don't talk about the HD1 but the PD1. The difference between HD1 and PD1 is HD1 is made for NTSC signals and also digitally outputs 1280x720, whereas PD1 is made for PAL signals and doesn't digitally output 1280x720 but only 720x576.

I wouldn't take the info given on the CineForm site as the HDV definition. It's just a list of supported formats.
Sample resources for HDV specs are here

www.gyhduser.com/article.php?filename=What-is-HDV-

or here

www.geocities.com/mammacow3/HDVSpec.htm.

Whereever there are HDV specs explained SD is not mentioned for HDV.

Marco

The SD modes are still recorded in HDV format. There is no differant or special format just for the SD modes. Everything any HDV camcorder records is in HDV format. Mpeg2-ts using a varied GOP structure and frame rate.
I would take the Cineform site and far more definative that those you listed. The HDV format contains a variety of resolutions and frame rates. Apparently more then you knew about.

>> The SD modes are still recorded in HDV format. There is no differant or
>> special format just for the SD modes. Everything any HDV camcorder
>> records is in HDV format. Mpeg2-ts using a varied GOP structure and
>> frame rate.

HDV does not support SD resolutions because HDV uses MP@H-14 encoding. The SD mode uses MP@ML for encoding (same as Sony's SD-based IMX and MicroMV and all DVD camera formats). Both formats are sent out via FireWire using MPEG-2/TS, so while the stream types are different (MP@H-14 vs. MP@ML), the stream interface is the same.

HDV supported formats:
--------------------------------
720 @ 25p, 30p, 50p and 60p.
1080 @ 50i and 60i

**

ATSC (over-the-air HDTV broadcasts) specifies:
----------------------------------------------
480 NTSC = 24p, 30p, 60p, and 60i
576 PAL = 25p, 50p and 50i
720 HDTV = 24p, 25p, 30p, 50p, 60p, 50i, and 60i
1080 HDTV = 24p, 25p, 30p, 50i and 60i

**

If you notice, Cineform, MainConcept and other MPEG-2 plug-ins for NLEs support most, if not all, ATSC's formats, not just HDV. These plug-ins allow editing MPEG-2 streams, not just HDV. With ATSC supporting so many formats, it's easy to get confused as to what format is exactly supporting which format.

Now, the real question is to why Vegas is displaying the PD1's color information as 32-bit. Why is there an extra channel? On my HD10U SD footage, I get 24-bit in Premiere Pro 1.51 using MainConcepts MPEG Pro.

Marco - can you email me a 15-second raw M2T stream from the PD1? I'd like to take a look at the stream.

One weird thing about the HD1/HD10U is that the colorspace for HD-output is SD's ITU-BT.601 colorspace, not the 709 HD spec, so it's not like there is an expanded gamut or something.

>> On my HD10U SD footage, I get 24-bit in Premiere Pro 1.51 using MainConcepts MPEG Pro.

This is interesting. So it's either the PD1 producing a different stream or it's Vegas analyzing something wrong (or it's the Vegas capture tool producing a strange kind of header).

>> Marco - can you email me a 15-second raw M2T stream from the PD1?

Mailing you a short file is no problem. But I think 15 seconds is too much for the space of my mail account (not sure - I think it's limited to 5 or 10 MB). Wouldn't be just 2 - 3 seconds enough?

Marco

"The SD mode uses MP@ML for encoding (same as Sony's SD-based IMX and MicroMV and all DVD camera formats)."

Where did you get that from? The SD mode of the HDV codec matches the HD mode. 19mbits/s, 16/9, but uses double the frame rate (60p)

If this helps:

http://www.geocities.com/mammacow3/mpeg2.htm
http://web.archive.org/web/20040703090647/http://wwwam.hhi.de/mpeg-video/papers/sikora/mpeg1_2/mpeg1_2.htm
http://web.archive.org/web/20040619010559/wwwam.hhi.de/mpeg-video/papers/sikora/mpeg1_2/mpeg-tables2.htm

"Your right that it only has two modes 576p25 (downsampled 720p) and 576p50"


Well, it has three modes if you count old fashioned DV!

By the way it might be relevant to note that, unless you're outputting that old DV, the PD1 outputs 50p only.

Whether you output 25p or 50p footage, it comes out as 50p!

I'll say that again - if you output 25p it emerges NOT as 25p, NOT as 50i... but 50p.

It doesn't really matter because it's just every frame twice, but NLEs can get confused, or at least they did when I owned the cam.

This has lead to great confusion in the past, because the large number of HD1/0 owners who heard about it from the small number of PD1 owners often assumed it was a user error - that users were mistakenly shooting 50p not 25p, or that it was interlaced or something.

Nope - the PD1 outputs as 50p not only when you shoot 50p, but when footage is 25p.

Just another quirk of the PD1, probably unconnected, but worth mentionning just in case.

I just remembered something, I don't know where ever I got to mention it before. Often double frame rate schemes use a higher bandwidth. If this is the case, then using a mechanical/electric cinema film shutter to convert 50p to 25p (with 180 degree equivalent shutter) should yield much better compression. This would be a real boon to people using it for indie.

What are the data rates of the modes?

"What are the data rates of the modes?"

I'm not sure, as I sold my camera a while back.

However, I remember attaching the cam to a progressive monitor using the component cables and watching pre-recorded 25p footage (again, printed to tape within the 50p framework) and the quality was so good that the guys in the post production house said it looked like HDCAM.

I never saw the footage look that good again, though! It occured to me a great workflow would have been to shoot with the cam and then transfer all footage to DigiBeta via component...

Of course, a better workflow would have been to unlock the firmware and the HD capability!

I've finally gotten over that yearning now that I no longer own the cam...

I capture the PD1 HiRes stuff with the JVC capture tool and import it into Vegas. What I have there is 25p.

Marco

Do you mean that you captured hi-resolution (more than the normal SD frame) from the components ports?


Graham,

What i meant was what was the different data rates in Mb/s for the different modes?

Quality, I agree, if it is 19Mb/s SD, then that is nothing to be sneezed at. Pity they didn't do this instead of the GR-DV3000, I think a lot of people would have flown at for the price.

Maybe I should pick up a PD1, or HD10, for a few hundred latter this year. There must be a few floating around with all the new HD cameras that have come out.

"I capture the PD1 HiRes stuff with the JVC capture tool and import it into Vegas. What I have there is 25p"

Yes, I remember Vegas not being confused. Another great one was Sonic DVDit Pro 6, which accepted the m2t provided you renamed the extension mpg, didn't get thrown by the 50p structure either and burned the best quality PD1 DVDs I ever saw! Then, of course, there was Mpeg Edit Studio Pro LE which was tuned specifically for the PD1, just like it was tuned for the HD1/0.

The impression I had was that, as time was passing, new software releases were becoming more aware of the notion of 50p packaging of 25p and not getting so confused. I am not sure what the situation is now, as I no longer have access to the cam.

"Do you mean that you captured hi-resolution (more than the normal SD frame) from the components ports?"

No, just viewed it on a progressive monitor. Yes, I think JVC described it as Extended Definition in some of their publicity material and it was my (non-techie) understanding that it was exploiting SD space slightly better traditional SD.

"What i meant was what was the different data rates in Mb/s for the different modes?"

I simply don't know, sorry - I'm not very technical!

"Maybe I should pick up a PD1, or HD10, for a few hundred latter this year. There must be a few floating around with all the new HD cameras that have come out."

I think you could get one for a good price. I originally ordered the HD10 and actually changed the order to a PD1 because of the frame rate. I wouldn't do that again - I am more comfortable with 30p than I was two years ago. I would recommend a HD10. The PD1 was very nice when connected to a big progressive screen by component, but not so hot when simply editing and outputting with computer software.

In the end, the best thing about the PD1, in my opinion, was that it was true 16:9 25p. That could look very nice sometimes.

I just remembered something, I don't know where ever I got to mention it before. Often double frame rate schemes use a higher bandwidth. If this is the case, then using a mechanical/electric cinema film shutter to convert 50p to 25p (with 180 degree equivalent shutter) should yield much better compression. This would be a real boon to people using it for indie.

What are the data rates of the modes?

They use the exact same compression. The 25p mode is downsampled from 720p and recorded at 25p in a 50p wrapper. The 50p SD mode records twice the frames at double the GOP and half the resolution. Both use the same bandwidth. If the Hi-Res mode actually captured SD and not HD then downsampled to SD then yes there would be an advantage. But as it is, no. Same bandwidth.

"Do you mean that you captured hi-resolution (more than the normal SD frame) from the components ports?"

No, just viewed it on a progressive monitor. Yes, I think JVC described it as Extended Definition in some of their publicity material and it was my (non-techie) understanding that it was exploiting SD space slightly better traditional SD.

"What i meant was what was the different data rates in Mb/s for the different modes?"

I simply don't know, sorry - I'm not very technical!


Actually there is a way, either the editor would tell you what rate the clip is, or you could quote the megabytes of a clip and the length down to the second, for clips shot in different modes. I could do a rough calculation from there.


Component resolution test:

I have just thought, if anybody wanted to find out the resolution of the camera live through component in hires mode, you could do it filming a test chart and a true 1280 pixel wide TV monitor in the different modes. Setting up the camera and TV for best resolution, the TV either will tell you what resolution it is using (but that may not be accurate) but you can tell accurately by a change in the res charts. I must point out I am not talking about the resolution of recorded footage or testing it, but the controversy of what it pouts out via component.

They use the exact same compression. The 25p mode is down sampled from 720p and recorded at 25p in a 50p wrapper. The 50p SD mode records twice the frames at double the GOP and half the resolution. Both use the same bandwidth. If the Hi-Res mode actually captured SD and not HD then down sampled to SD then yes there would be an advantage. But as it is, no. Same bandwidth.
I virtually never say this (except with a certain German engineer) but I am confused, about what you meant. Ken, are you saying that the 25p and 50p SD modes (except MiniDV Dv codec mode) of the camera use the 19.6Mb/s same data rate as the 720p mode of the HD10?

Thanks for you help anyway, what do you think of my res chart testing idea? I know that this may be of little interest to people now, but if the component hi-res mode turns out to be uncompressed the HDU-1 HDSDI uncompressed recording unit by Keith Wakeham may get component in eventually. There is also an expensive component to HDSDI adaptor that could be used.

Wayne.

By the way, the great image I saw on the progressive monitor was from a tape playing in the camera.

I never thought to take off the lens cap, switch to record mode and see what it looked live!

"Do you mean that you captured hi-resolution (more than the normal SD frame) from the components ports?"

I captured HiRes 25p as .m2t-stream via firewire.

Marco

Thanks Marco.