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Old September 28th, 2005, 05:16 AM   #1
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PD1 SD with 32 Bit?

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?

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Old September 30th, 2005, 04:41 PM   #2
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HDV is 8-bit. Are you changing codec?
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Old October 4th, 2005, 03:04 PM   #3
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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.

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Old October 4th, 2005, 05:40 PM   #4
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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.
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Old October 5th, 2005, 03:25 PM   #5
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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.

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Old October 9th, 2005, 07:07 PM   #6
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The PD1 is not HDV but a special SD MPEG2 stream only. So maybe somebody can help him?
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Old October 10th, 2005, 01:47 PM   #7
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The PD1 records in HDV format.
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Old October 10th, 2005, 03:37 PM   #8
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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?

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Old October 10th, 2005, 06:43 PM   #9
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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?
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Old October 10th, 2005, 07:34 PM   #10
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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).
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Old October 11th, 2005, 12:34 AM   #11
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>> 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. ;)

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Old October 11th, 2005, 02:11 AM   #12
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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/Asp...m#AHD_Features
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Old October 11th, 2005, 03:08 AM   #13
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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

http://www.gyhduser.com/article.php?...e=What-is-HDV-

or here

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

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

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Old October 11th, 2005, 01:03 PM   #14
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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.
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Old October 12th, 2005, 02:55 AM   #15
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>> 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.
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