Frame Rate Mystery

Graham Jones · August 9th, 2004, 03:01 AM

no, i haven't seen hd10u 35mm transfer - but we need people like you to pioneer that!

Chris Hurd · August 9th, 2004, 06:16 AM

Having seen "28 Days Later" on both the big screen and DVD, I will definitely say that it looked worse in theaters. It looked much better in my living room on my 31" consumer television.

Graham, the 50p / 50i thing is just a matter of conventions. There is no accepted standard of 50p, the manufacturer simply miswrote it in the manual. The reference is of course to 25p. Whoever wrote the manual (most likely it is a translation from Japanese anyway) is most likely unaware of the accepted convention of describing that particular frame rate as 25p, as opposed to 50p as it's printed.

Basically it all boils down to your choice of either interlace (50 fields / sec.) or progressive (25 frames / sec.) -- that's all that's really going on here. The manual has been written in an unintentionally confusing manner is all.

Graham Jones · August 9th, 2004, 06:33 AM

that would make me happy Chris, but I'm not convinced it's a typo.

See this parallel thread, where i go into a little more detail

http://www.dvinfo.net/conf/showthrea...threadid=30192

Moderator note: other thread link removed and correct one inserted. -Rob

David Newman · August 9th, 2004, 09:35 AM

I just posted this into the other thread also:

It is not an issue. 50p analog output is simply so that the frame doesn't flicker like crazy. Even 24p film is displayed at 48Hz, with each frame being flashed on the screen twice. You are shooting 25p, if you are editing from the IEEE1394 signal you are editing 25p.

However, the PD1's MPEG transport stream does indicate 50 discrete frames -- this is where some software is getting confused. The MPEG stream marks repeat frames, just the same way 24P film is encoded onto 30fps only NTSC DVDs. The repeat frames do not take a significant slice of the bit-stream, but editing software does need to be aware of it.

Graham Jones · August 9th, 2004, 10:54 AM

that's illuminating... i'm going to leave this thread now and continue in the othe thread at http://www.dvinfo.net/conf/showthread.php?postid=210238#post210238

August 9th, 2004, 06:16 AM	#17
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,369 Images: 513	Having seen "28 Days Later" on both the big screen and DVD, I will definitely say that it looked worse in theaters. It looked much better in my living room on my 31" consumer television. Graham, the 50p / 50i thing is just a matter of conventions. There is no accepted standard of 50p, the manufacturer simply miswrote it in the manual. The reference is of course to 25p. Whoever wrote the manual (most likely it is a translation from Japanese anyway) is most likely unaware of the accepted convention of describing that particular frame rate as 25p, as opposed to 50p as it's printed. Basically it all boils down to your choice of either interlace (50 fields / sec.) or progressive (25 frames / sec.) -- that's all that's really going on here. The manual has been written in an unintentionally confusing manner is all. __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

August 9th, 2004, 09:35 AM	#19
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	I just posted this into the other thread also: It is not an issue. 50p analog output is simply so that the frame doesn't flicker like crazy. Even 24p film is displayed at 48Hz, with each frame being flashed on the screen twice. You are shooting 25p, if you are editing from the IEEE1394 signal you are editing 25p. However, the PD1's MPEG transport stream does indicate 50 discrete frames -- this is where some software is getting confused. The MPEG stream marks repeat frames, just the same way 24P film is encoded onto 30fps only NTSC DVDs. The repeat frames do not take a significant slice of the bit-stream, but editing software does need to be aware of it. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

August 9th, 2004, 03:01 AM	#16
Graham Jones Major Player Join Date: Jan 2004 Location: Europe Posts: 489	no, i haven't seen hd10u 35mm transfer - but we need people like you to pioneer that!

August 9th, 2004, 06:33 AM	#18
Graham Jones Major Player Join Date: Jan 2004 Location: Europe Posts: 489	that would make me happy Chris, but I'm not convinced it's a typo. See this parallel thread, where i go into a little more detail http://www.dvinfo.net/conf/showthrea...threadid=30192 Moderator note: other thread link removed and correct one inserted. -Rob

August 9th, 2004, 10:54 AM	#20
Graham Jones Major Player Join Date: Jan 2004 Location: Europe Posts: 489	that's illuminating... i'm going to leave this thread now and continue in the othe thread at http://www.dvinfo.net/conf/showthread.php?postid=210238#post210238