capturing 720/25p with capdvhs at DVinfo.net

Nima Taheri · July 9th, 2008, 07:24 AM

Has anyone experienced when capturing 720/25p footage with capdvhs, that the .m2t-file becomes 50p? When I capture the footage from the Brhd50, and check the framerate, it says 50. I tried the same with the 30p footage, but that worked, also with 60p footage. but when it comes to 25p, it captures it as 50p? anyone?

Tim Dashwood · July 9th, 2008, 06:09 PM

The ProHD cameras can acquire many different frame rates but technically only 'record' and output two formats: 720p50 and 720p60. The various possible acquisition frame rates need to be placed within either those 50 or 60 frames per second in order to maintain a 720p50 or 720p60 output that adheres to broadcast standards.

In the case of 720p25 the math is very simple and each acquired frame is doubled up and 'recorded' as 2 frames as it is layed to tape. (These are sometimes referred to as repeat flags.) When you capture this 720p50 m2t stream with a simple m2t capture tool like CapDVHS everything will be captured natively resulting in a 720p50 file with paired frames.
A "smart" capture tool found in a compatible NLE (Vegas, FCP, Avid MC3, etc) will recognize the "flagged" frames as 25p and simply throw away the unnecessary doubles.

In 720p24 mode the math is more complicated since 24 will not divide evenly into 50 or 60.
Instead 720p60 is used as the recording format and the first acquired frame will be doubled up and recorded twice, then the next frame will be tripled and recorded on three frames and so on. This pattern is known as 2:3 pulldown and is a bit of a headache in post if not removed properly.

I put the word record in quotes because there are actually some more complicated things going on under the hood in the way JVC efficiently encodes with repeat flags in a 6 frame GOP but hopefully the above answers your question.

Oscar Honorio Pantoja · July 9th, 2008, 09:06 PM

When the dropp`s tape is detect for capvhs, The m2t file is wrong and say: property:50p,60p in the 24p tape recorded.

Nima Taheri · July 10th, 2008, 09:54 AM

Quote:

Originally Posted by Tim Dashwood

In the case of 720p25 the math is very simple and each acquired frame is doubled up and 'recorded' as 2 frames as it is layed to tape. (These are sometimes referred to as repeat flags.) When you capture this 720p50 m2t stream with a simple m2t capture tool like CapDVHS everything will be captured natively resulting in a 720p50 file with paired frames.
A "smart" capture tool found in a compatible NLE (Vegas, FCP, Avid MC3, etc) will recognize the "flagged" frames as 25p and simply throw away the unnecessary doubles.

If I want to still use CapDVHS for capturing, can I just import the .m2t file (50p) in MpegStreamclip and then export as 25p without losing any information? The reason that I'm asking is because I keep having trouble capturing 720p footage in FCP, and it would make life easier to stick with the workflow of using CapDVHS and MpegStreamclip

Tim Dashwood · July 10th, 2008, 10:14 AM

Quote:

Originally Posted by Nima Taheri

If I want to still use CapDVHS for capturing, can I just import the .m2t file (50p) in MpegStreamclip and then export as 25p without losing any information? The reason that I'm asking is because I keep having trouble capturing 720p footage in FCP, and it would make life easier to stick with the workflow of using CapDVHS and MpegStreamclip

Yep. That will work fine. Just specify 25 as the frame rate in the export window.

Seamus Byrne · January 19th, 2009, 11:36 AM

Quote:

Originally Posted by Tim Dashwood

Yep. That will work fine. Just specify 25 as the frame rate in the export window.

Hi. I'm having the very same problem capturing 720p 25fps footage from my GY HD-110E into Movie Edit Pro 14 Plus (and also into Magix's new Video Pro X). It appears on the timeline as 50p. I checked it in Avid Liquid and it IS 50p.

Can I export it from Movie Edit Pro as 720p 25p without any loss?

Seamus.

Seamus Byrne · January 19th, 2009, 11:56 AM

Just to answer my own question there - I attempted to export as 720p 25p, but, after a long time, the result was still 50p!

So my next question is - is there a simple capturing tool that will capture my 25p as 25p in its original quality?

Seamus.

July 9th, 2008, 07:24 AM	#1
Nima Taheri Regular Crew Join Date: Mar 2006 Location: Norway Posts: 136	capturing 720/25p with capdvhs Has anyone experienced when capturing 720/25p footage with capdvhs, that the .m2t-file becomes 50p? When I capture the footage from the Brhd50, and check the framerate, it says 50. I tried the same with the 30p footage, but that worked, also with 60p footage. but when it comes to 25p, it captures it as 50p? anyone?

July 9th, 2008, 06:09 PM	#2
Tim Dashwood Wrangler Join Date: Aug 2005 Location: Toronto, ON, Canada Posts: 3,637	The ProHD cameras can acquire many different frame rates but technically only 'record' and output two formats: 720p50 and 720p60. The various possible acquisition frame rates need to be placed within either those 50 or 60 frames per second in order to maintain a 720p50 or 720p60 output that adheres to broadcast standards. In the case of 720p25 the math is very simple and each acquired frame is doubled up and 'recorded' as 2 frames as it is layed to tape. (These are sometimes referred to as repeat flags.) When you capture this 720p50 m2t stream with a simple m2t capture tool like CapDVHS everything will be captured natively resulting in a 720p50 file with paired frames. A "smart" capture tool found in a compatible NLE (Vegas, FCP, Avid MC3, etc) will recognize the "flagged" frames as 25p and simply throw away the unnecessary doubles. In 720p24 mode the math is more complicated since 24 will not divide evenly into 50 or 60. Instead 720p60 is used as the recording format and the first acquired frame will be doubled up and recorded twice, then the next frame will be tripled and recorded on three frames and so on. This pattern is known as 2:3 pulldown and is a bit of a headache in post if not removed properly. I put the word record in quotes because there are actually some more complicated things going on under the hood in the way JVC efficiently encodes with repeat flags in a 6 frame GOP but hopefully the above answers your question. __________________ Tim Dashwood

July 9th, 2008, 09:06 PM	#3
Oscar Honorio Pantoja Regular Crew Join Date: Oct 2006 Location: Lima, Perú Posts: 37	When the dropp`s tape is detect for capvhs, The m2t file is wrong and say: property:50p,60p in the 24p tape recorded. __________________ 4:3 don´t go!!

January 19th, 2009, 11:56 AM	#7
Seamus Byrne New Boot Join Date: Nov 2007 Location: Wicklow, Ireland Posts: 20	720p 25fps captured as 50fps Just to answer my own question there - I attempted to export as 720p 25p, but, after a long time, the result was still 50p! So my next question is - is there a simple capturing tool that will capture my 25p as 25p in its original quality? Seamus.