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Old March 9th, 2009, 04:34 PM   #1
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Confusion on codec

I have a question about the codes on new line of JVC cameras. In the past GY100- 250 used HDVPro mpeg2 long GOP compression. Unfortunately sometimes it suffer from artifacts (like blocking on fast pans). HVCHD is apparently better in this category. So my question is how does the new XDCAM stacking against the old system?
The reason I am asking is I am supposed to shoot some ski footage this spring and a lot more next season. I was not happy with some of the shots from GY-HD100. So I am trying to decide between Panasonic AVCCAM (cheaper plus wide angle lens, but pain to edit in FCP) and new JVC (more $$ and 39mm lens, but no pain with FCP) . So I am trying to find out if the new codec used by JVC will be more robust then the HDVPro.
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Old March 10th, 2009, 05:45 AM   #2
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I have a sony EX1 - I never get any blocking ever - the codec is superb - best data rate/picture quality codec out there - panny is 3x data rate for comparable picture
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Old March 13th, 2009, 05:59 AM   #3
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35 Mbps VBR seems more then enough to get rid of blocking artifacts with heavy motion. If you are shooting 720p50 or 720p60 (as I suppose you will for all the fast action), the bandwith you had on the GY-H2xx was 19.7 Mbps (CBR), that has now almost doubled to 35 Mbps (and on top it is variable (VBR), it uses bandwith where it's needed the most, so to speak) - you should more then be okay.
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Old March 13th, 2009, 07:54 PM   #4
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Quote:
Originally Posted by Robert Rogoz View Post
So my question is how does the new XDCAM stacking against the old system?
I saw a 2-page add for the 700 today. I had long been wondering how JVC would describe "what" it was encoding.

I was sure Sony would never allow JVC to say they recorded XDCAM EX unless they used a Sony codec or licensed the Sony firmware. The HOW of encoding determines video quality -- and Sony feels its MPEG-2 encoder is the best -- naturally. But, the fact blocking artifacts aren't seen on Sony XDCAM EX video is a testament to how well SONY does encoding.

Since JVC has always proudly claimed the new codec was its own -- that meant JVC could never say it encoded XDCAM EX even when it wrote the encoded files to SxS cards.

And, indeed the JVC never says what codec is used -- only one word in a list of features "ProHD." It appears the definition of ProHD is been expanded.

We are told there are three data rates: 35, 25, and 19. We are told recordings can be made to SDHC. We are told there are various frame sizes and rates. We are told we get an FCP "format."

Lastly we are told a "compatible .mp4 file format on XDCAM EX" is the other format. So what's recorded is never XDCAM EX. What's recorded is .mp4 which "is the compliant file format used on the XDCAM EX."

Grammatically, of course, this is nonsense. "... the EXCAM EX" perhaps should be "by XDCAM EX" which is the weakest form of association possible. Basically JVC says what it records is compliant with the definition of what Sony calls XDCAM EX.

This is not a meaningless distinction. They question repeatedly asked is HOW will recordings look. The answer given way too often is SINCE IT'S XDCAM EX and XDCAM EX looks great -- so will JVC recordings.

It looks like JVC licensed only the file specification -- the ability to write using the same data specification as used by XDCAM EX. But, there can be no claim by anyone that the actual data are the same. Hence, folks should stop saying the new camera encodes XDCAM EX -- it does not.

Moreover, JVC footnotes that the .mp4 files may not playback due to differences in recording modes -- meaning, of course, don't expect 19Mbps data to be played by Sony equipment. (Will current XDCAM EX software decoders work with 19Mbps? In particular, 720p24 ProHD.)

But, here's something else interesting. The SxS cards are not linked to XDCAM EX. SxS is `professional media with a PCI interface.' You can record to SxS simultaneously with recording to SDHC. So technically the cards full of data can't be said to be carrying EXDCAM EX. Likewise, SDHC carries the same data with the same data specification as what's recorded on SxS. (Although, one wonders if the Sony SxS Browser will read SDHC media.)

PS: the word "MPEG-2" never appears in the ad. And, the size and pixel count of the CCDs are never mentioned either.
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Old March 14th, 2009, 07:24 PM   #5
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Thanks for reply. However I am more confused then before. Specially after reading the pages form the official brochure.
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Old March 16th, 2009, 03:11 AM   #6
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Quote:
Originally Posted by Robert Rogoz View Post
Thanks for reply. However I am more confused then before. Specially after reading the pages form the official brochure.
What are you confused about?

19, 25, 35Mbps long GOP MPEG-2 written with either a .mp4 or .mov wrapper to SDHC and/or SxS.

Audio is 2-channel 48kHz 16-bit PCM.

The .mp4 files are compatible with XDCAM EX in a .mp4 wrapper.

The .mov files are compatible with FCP.

This is how the files function. Seems like the "format" is called ProHD.

What it can't be called is XDCAM EX because it was encoded by a Sony encoder.
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Old March 16th, 2009, 06:46 AM   #7
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Not sure why you're saying it can't be called XDCAM EX----that is the format that showed up for Tim Dashwood when he brought the clips into Premiere and I believe Final Cut Pro when he was testing.
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Old March 16th, 2009, 10:27 AM   #8
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Quote:
Originally Posted by Steve Harryman View Post
Not sure why you're saying it can't be called XDCAM EX----that is the format that showed up for Tim Dashwood when he brought the clips into Premiere and I believe Final Cut Pro when he was testing.
If I understand Steve Mullen correctly, "real" XDCAM EX has to be encoded by a Sony encoder.

The new JVC cameras use a new JVC encoder.

The only relation the video has to XDCAM EX video recorded on a Sony XDCAM EX camera is the MP4 file format that is written/packaged like it is on the XDCAM camera.

In fact, in the JVC brochure for the HM700 camera, the text on Page 8 says:

"The optional SxS media recorder allows simultaneous shooting to
SDHC and SxS media. This hybrid recording system not only
provides a reliable backup solution, it also allows the GY-HM700U to
integrate smoothly into any MP4 file-based workflow. This file format
is compatible with all major NLE systems, including solutions from
Adobe, Avid and Canopus."

Then in a footnote below the preceding paragraph the brochure says, "* MP4 is the compliant file format used on the XDCAM EX."

This is the only mention of XDCAM EX in the entire 16 page brochure. In fact, this footnote is referring to the Sony camera, not the video. The note simply establishes that the Sony XDCAM EX camera records in an MP4 format the same as the new Sony camera does.

How good the video is is going to depend on how the new JVC encoder performs. The quality of the video actually has no relation whatsoever to the video recorded on the XDCAM EX camera except that the final file is in the same format.

It would seem the significance of the new JVC cameras is that no matter what computer one is using, MAC or PC, one can record in a format that will edit/open directly in just about any NLE. (i.e. *.mov for Macs and XDCAM flavor MP4 for PCs)
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Old March 16th, 2009, 12:29 PM   #9
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I'm just saying that Tim mentioned the clips he shot with the GY-HM700 are in the XDCAM EX codec and showed that in Premiere when he imported the .mov files. Here's a couple clips from another thread from Tim:

Quote:
Originally Posted by Tim Dashwood
The codec used with the HM700 is XDCAM EX at bit rates up to 35Mbps.
The wrapper/container used on a new "out-of-the-box" HM700 is Quicktime .MOV and it can be written to SDHC cards.
The addition of the KA-MR100 SxS module will allow the ability to write XDCAM EX to SxS cards in the MP4 container, but will also unlock the ability to write XDCAM EX to SDHC cards in the MP4 container.

Premiere Pro CS4 natively supports XDCAM EX MP4 files. I downloaded the trial and imported them easily. It seems that XD Decode will allow you to import XDCAM EX .MOV files on a PC but I am in the process of testing this.

On the Mac you don't even really need FCP installed if you download and install the open-source XDCAM EX codec. This even works with Sony's XDCAM Transfer software.
Quote:
Originally Posted by Tim Dashwood
I installed XD Decoder on Windows XP and was able to open the Quicktimes in Quicktime player without issue. I assume this means that any Windows application that supports Quicktime will work with these files but I'm downloading the Premiere Pro CS4 demo for XP now and will have some more answers soon.

--------------------------------------------------------------------------------------

Success! I was able to import the Quicktime files directly into Premiere Pro CS4 on Windows XP without the need to transcode. The properties of the imported .mov clips properly report XDCAM EX as the codec and all of the sizes and frame rates seem to work. (The gray bars are the watermarking done by the trial version of XD Decoder.)

Tim Dashwood
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Old March 16th, 2009, 01:23 PM   #10
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Not to belabor the point, but the XDCAM EX codec is MP4.

Apparently, JVC is using this Sony scheme of MP4, so it might show up as XDCAM EX in an NLE that is programmed to name this MP4 as XDCAM EX.

Nevertheless, the video is being encoded by the new JVC encoder, not a Sony encoder. The video is JVC video, not XDCAM EX video.

According to the JVC literature, the native file format is Quicktime. However, the cameras can also encode to the MP4 file format, and the "flavor" of MP4 that is encoded to is the Sony XDCAM EX format (maybe), but the video is 100% JVC encoder video.

I assume one can take a direct feed off the camera and encode it into any other format instead, such as Cineform.
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Old March 16th, 2009, 01:27 PM   #11
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Steve,

I think what Steve Mullen and Jack are saying is that the codec may be licsenced
from Sony, but the implementation within the DSP combined with the CCD is different. So, don't expect an apples to apples comparison. It will be a little different, hopefully better, hopefully as good, or hopefully good.

Correct me if I'm wrong.

Cheers.
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Old March 16th, 2009, 01:49 PM   #12
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I'll try to wade through the FUD here and state the bottom line...again.

The HM series cameras encode mpeg2 long-GOP streams at 19/25/35 Mbps with JVC's encoder and write them into the XDCAM EX codec wrapped as either .mov or .mp4.

The only restriction is that the mp4 wrapper cannot be "unlocked" for SDHC on the HM700 until the KA-MR100 SxS unit is attached to the camera. The HM100 will record both formats to SDHC cards. Only mp4 wrapped media can be recorded to the SxS cards.

Your NLE software won't know the difference between mp4 clips generated by the EX1/3 or HM100/700. They will always be recognized as XDCAM EX clips.

The terms of JVC's XDCAM EX license with Sony are not public but I would assume that the encoders have nothing to do with why XDCAM EX isn't mentioned more in the marketing of the HM series cameras. This is a JVC product directly competing with Sony's own EX products, so I find it amazing that Sony even agreed to license the codec.
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Old March 16th, 2009, 10:58 PM   #13
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Tim and Steve- Thanks for the explanations, which are much more clear then in the brochure itself. What I was confused about is the use of term "ProHD", which is totally different from let's say HD100.
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Old March 17th, 2009, 12:01 AM   #14
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Quote:
Originally Posted by Matt San View Post
I have a sony EX1 - I never get any blocking ever - the codec is superb - best data rate/picture quality codec out there - panny is 3x data rate for comparable picture

I have a Sony EX1 (or use one at work) and it is a great camera, though with the rolling shutter I am not sure that I would use it for fast motion subjects like skiers.

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Old March 17th, 2009, 05:03 AM   #15
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Quote:
Originally Posted by Tim Dashwood View Post
I'll try to wade through the FUD here and state the bottom line...again.

The HM series cameras encode mpeg2 long-GOP streams at 19/25/35 Mbps with JVC's encoder and write them into the XDCAM EX codec wrapped as either .mov or .mp4.
1) It would make no sense to encode video as long-GOP MPEG2 using the JVC encoder and then "write them into the XDCAM EX codec." First, nothing "writes" into a codec. Second, already encoded data would never be sent into a codec. To use previously JVC encoded data, the data would have to be decoded to baseband and then re-encoded as XDCAM EX-- causing a loss in quality.

2) Streams are not sent into a codec as .mov or .mp4. Encoded data coming-OUT of a codec IS THEN wrapped as .mov or .mp4.

3) It seems you are saying there is a second (Sony?) codec.

The flow you describe is backwards. Or, you didn't use the word "codec" correctly.

----------

When .mp4 is written to SDHC by the HM100 -- are these files seen as XDCAM EX? You say YES, but at no point in the HM100 brochure are there the words XDCAM EX. Only the word ".mp4." And, there are the JVC ProHD Clip Manager and a FCP ProHD Log and Transfer Plug-in just for the .mp4 files. If these files seen as XDCAM EX, why would FCP need a ProHD Log and Transfer Plug-in?

1) The box could, as some have suggested, be a big dongle that helps pay for the right to write XDCAM EX compatible .mp4. (The camera would do the actual wrapping.)

2) Or, it could have a Sony encoder -- in which case why isn't JVC promoting the fact you get Sony encoded XDCAM EX when you buy the box? Perhaps, this is part of the license?

3) Or, it could contain "something" -- perhaps OEMed from Sony that wraps the JVC encoded data to .mp4 files that are compatible with XDCAM EX. (Tim, perhaps this is what you were trying to describe.) However, I thought wrapping is always done by the encoder itself.

-----------

1) Without the SxS box -- can the HM700 write the same kind of .mp4 files to SDHC as can the HM100? If so, do you get the JVC JVC ProHD Clip Manager and a ProHD Log and Transfer Plug-in?

2) Why does the HM700 brochure always say .mp4 (the kind compatible with XDCAM EX) is written to SxS and SDHC simultaneously? Does that mean you always need both types of cards inserted?
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Last edited by Steve Mullen; March 17th, 2009 at 12:45 PM.
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