140 and 160 Mbps Long GOP, 220 Mbps I-Frame Only

Justin Benn · July 3rd, 2009, 05:39 AM

[Ooops! Double post]

Steve Phillipps · July 3rd, 2009, 05:43 AM

Quote:

Originally Posted by Justin Benn

You will make my Xmas if you manged to get uncompressed 10 bit on the XDR before the year is out!

Jus.

First though I'd suggest you give your local hard drive retailer a call to make sure he has enough stock!
Steve

Thomas Smet · July 3rd, 2009, 07:36 AM

My thanks goes to Convergent Design for the simple fact that they destroyed the industry myth that mpeg2 is a bad format. I have worked with high bitrate I frame only mpeg2 for a long time and it really is one of the best formats I have ever used. CD managed to make mpeg2 cool which is not an easy task. It took these guys to finally convince the world just how much potential the format really had.

Dan Keaton · July 3rd, 2009, 08:28 AM

Dear Justin and Thomas,

We sincerely appreciate your comments.

I never thought of it that way, but I can assure you that MPEG is a great format, especially when using high bit-rates.

Here are some facts, as I know them:

HDV cameras, and most other HD cameras at the time, as far as I know, were almost always 1440 x 1080 format (for 1080). HD is 1920 x 1080 (for 1080).

This simple fact and the processing power that it takes to convert 1440 x 1080 gave editing HDV a bad name. I believe most people attributed the bad name to Long GOP.

Converting 1440 x1080 to 1920 x 1080 is actually very easy, if you have a dedicated circuit to perform the task. But converting it in software requires millions of instructions for every frame, and thus millions and millions of instructions per second.

While this does not really task our high speed computers of today, it is a load on the computers.

Our MPEG-2, is always recorded at full raster, 1920 x 1080, even if the camera's sensor is 1440 x 1080. One thing that helps us, is that the 1440 x 1080 to 1920 x 1080 conversion always takes place in the camera itself, prior to transmitting the data via HD-SDI or HDMI.

This allows us to record full raster, 1920 x 1080, which we do.

Then our MPEG-2, when it reaches the MPEG-2 decoding software in a computer, does not need to waste any precious instructions converting 1440 x 1080 to 1920 x 1080.

Thus, computers can handle our MPEG-2 Long GOP much more efficiently than HDV.

Recording full raster, in other words, recording every pixel, is good for us, good for your computer's efficiency, and excellent for your image.

As a side note, another codec, DVCPro HD, first throws away some of the resolution, then performs compression. These discarded pixels can never be restored.

I have been asking professional individuals, at trade shows, if they can detect any visible evidience that they are watching a playback, or the live image. Even on very careful examination, using a good Sony or Cinetal 1920 x 1080 monitor, no one has ever detected a difference.

We have said for some time now, that 100 Mbps GOP is the sweet spot. We feel that this format offers images that are visually indishinguishable from uncompressed live images.

We now offer 140 and 160 Mbps Long GOP as menu selectable options. It may not be necessary, but we offer it for those who want to test it and ultimately use it for their productions.

For those who want to use I-Frame, we offer 100/140/160 and 220 Mbps I-Frame Only bit-rate options. One of these options may be best for your workflow. We do know that Avid works very well with I-Frame, even at bit rates higher than 220 Mbps.

Nic van Oudtshoorn · July 4th, 2009, 04:40 PM

Quote:

Originally Posted by Justin Benn

Just wanted to add my voice to the clarion of thanks and appreciation that you guys deserve.
You will make my Xmas if you manged to get uncompressed 10 bit on the XDR before the year is out!

Jus.

May I add my thanks for your product and your continuing FREE firmware upgrades that continue to improve an already fine piece of equipment. I find the quality of the captures really excellent and any problems I have had (including a warranty repair) have been solved prompty and most professionally. And yes, I agree with Justin .... uncompressed eventually will be great!

Dan Keaton · July 4th, 2009, 05:03 PM

Thanks Nic,

There are more free features to come.

We have two that we are working on that we have never discussed, we are keeping these as surprises.

July 3rd, 2009, 05:39 AM	#16
Justin Benn Major Player Join Date: Oct 2006 Location: York, UK. Posts: 224	Gratitude. [Ooops! Double post] Last edited by Justin Benn; July 3rd, 2009 at 05:41 AM. Reason: Too hasty.

July 3rd, 2009, 08:28 AM	#19
Dan Keaton Inner Circle Join Date: Dec 2002 Location: Augusta Georgia Posts: 5,421	Dear Justin and Thomas, We sincerely appreciate your comments. I never thought of it that way, but I can assure you that MPEG is a great format, especially when using high bit-rates. Here are some facts, as I know them: HDV cameras, and most other HD cameras at the time, as far as I know, were almost always 1440 x 1080 format (for 1080). HD is 1920 x 1080 (for 1080). This simple fact and the processing power that it takes to convert 1440 x 1080 gave editing HDV a bad name. I believe most people attributed the bad name to Long GOP. Converting 1440 x1080 to 1920 x 1080 is actually very easy, if you have a dedicated circuit to perform the task. But converting it in software requires millions of instructions for every frame, and thus millions and millions of instructions per second. While this does not really task our high speed computers of today, it is a load on the computers. Our MPEG-2, is always recorded at full raster, 1920 x 1080, even if the camera's sensor is 1440 x 1080. One thing that helps us, is that the 1440 x 1080 to 1920 x 1080 conversion always takes place in the camera itself, prior to transmitting the data via HD-SDI or HDMI. This allows us to record full raster, 1920 x 1080, which we do. Then our MPEG-2, when it reaches the MPEG-2 decoding software in a computer, does not need to waste any precious instructions converting 1440 x 1080 to 1920 x 1080. Thus, computers can handle our MPEG-2 Long GOP much more efficiently than HDV. Recording full raster, in other words, recording every pixel, is good for us, good for your computer's efficiency, and excellent for your image. As a side note, another codec, DVCPro HD, first throws away some of the resolution, then performs compression. These discarded pixels can never be restored. I have been asking professional individuals, at trade shows, if they can detect any visible evidience that they are watching a playback, or the live image. Even on very careful examination, using a good Sony or Cinetal 1920 x 1080 monitor, no one has ever detected a difference. We have said for some time now, that 100 Mbps GOP is the sweet spot. We feel that this format offers images that are visually indishinguishable from uncompressed live images. We now offer 140 and 160 Mbps Long GOP as menu selectable options. It may not be necessary, but we offer it for those who want to test it and ultimately use it for their productions. For those who want to use I-Frame, we offer 100/140/160 and 220 Mbps I-Frame Only bit-rate options. One of these options may be best for your workflow. We do know that Avid works very well with I-Frame, even at bit rates higher than 220 Mbps. __________________ Dan Keaton Augusta Georgia

July 4th, 2009, 05:03 PM	#21
Dan Keaton Inner Circle Join Date: Dec 2002 Location: Augusta Georgia Posts: 5,421	Thanks Nic, There are more free features to come. We have two that we are working on that we have never discussed, we are keeping these as surprises. __________________ Dan Keaton Augusta Georgia

July 3rd, 2009, 07:36 AM	#18
Thomas Smet Trustee Join Date: Mar 2004 Location: Milwaukee, WI Posts: 1,719	My thanks goes to Convergent Design for the simple fact that they destroyed the industry myth that mpeg2 is a bad format. I have worked with high bitrate I frame only mpeg2 for a long time and it really is one of the best formats I have ever used. CD managed to make mpeg2 cool which is not an easy task. It took these guys to finally convince the world just how much potential the format really had.