HDV1

Robert Niemann · November 1st, 2005, 03:34 PM

Does somebody know, why HDV1 720p uses only 19 Mbps? Would it not have been better to use 25 Mbps and to shorten the GOP? And what is the difference between Transport Stream and Packetized Elementary Stream?

David Kennett · November 1st, 2005, 06:05 PM

The older JVC cams are fully compatable with DVHS and are below the broadcast stream maximum of 19.3 Mb/s. That's the only reason I can see. If I have read some posts correctly, the Sony cams cannot make a direct firewire copy to DVHS like JVCs.

Matt Irwin · November 2nd, 2005, 02:23 PM

I believe the total bandwidth is 25mbps, including audio. So 19mbps for video, 6mbps for audio...?

Steve Mullen would probably be the one to answer this...

Stephen Finton · November 2nd, 2005, 03:55 PM

The bandwidth of DVHS is 28.2 Mbps, not 19.3...

SONY probably just booby-trapped their cameras.

John Mitchell · November 3rd, 2005, 03:32 AM

The other potential reason is that 19mb/s on the same area of tape gives you a wider track pitch and therefore less chance of droputs.

Same reason Sony elected a higher tape speed for DV-Cam

Steve Crisdale · November 4th, 2005, 07:04 AM

The answer to this appeared on this forum ages ago... so a search may not find it for you!

The 19.3Mbit 720p data rate was based on the maximum Broadcast HD bit-rate.

The 25Mbit data rate was based on the maximum data capacity of Mini-DV tape.

Just a difference in philosophy, rather than some exotic conspiracy by megalomaniac corporate executives!!

Hse Kha · November 6th, 2005, 03:28 PM

Quote:

Originally Posted by Matt Irwin

6mbps for audio...

Does it capture 10 tracks of 5.1 audio??? :)

Ken Hodson · November 7th, 2005, 01:11 AM

"The 19.3Mbit 720p data rate was based on the maximum Broadcast HD bit-rate."
What? Any link to that?

19.3Mb/s plus two channels PCM audio.

November 1st, 2005, 03:34 PM	#1
Robert Niemann Regular Crew Join Date: Mar 2005 Location: Berlin, Federal Republic of Germany Posts: 109	HDV1 - why not 25 Mbps? Does somebody know, why HDV1 720p uses only 19 Mbps? Would it not have been better to use 25 Mbps and to shorten the GOP? And what is the difference between Transport Stream and Packetized Elementary Stream?

November 1st, 2005, 06:05 PM	#2
David Kennett Major Player Join Date: Jul 2003 Location: North Ridgeville, Ohio Posts: 407	The older JVC cams are fully compatable with DVHS and are below the broadcast stream maximum of 19.3 Mb/s. That's the only reason I can see. If I have read some posts correctly, the Sony cams cannot make a direct firewire copy to DVHS like JVCs. __________________ Dave

November 2nd, 2005, 02:23 PM	#3
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	I believe the total bandwidth is 25mbps, including audio. So 19mbps for video, 6mbps for audio...? Steve Mullen would probably be the one to answer this... __________________ Matt Irwin DP / matt.irwincine.com

November 7th, 2005, 01:11 AM	#8
Ken Hodson Trustee Join Date: Aug 2003 Location: Vancouver BC Canada Posts: 1,315	"The 19.3Mbit 720p data rate was based on the maximum Broadcast HD bit-rate." What? Any link to that? 19.3Mb/s plus two channels PCM audio. __________________ Damnit Jim, I'm a film maker not a sysytems tech.

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November 2nd, 2005, 03:55 PM	#4
Stephen Finton Major Player Join Date: Jun 2005 Location: Houston, TX Posts: 344	The bandwidth of DVHS is 28.2 Mbps, not 19.3... SONY probably just booby-trapped their cameras.

November 3rd, 2005, 03:32 AM	#5
John Mitchell Contributor Join Date: Jul 2005 Location: Sydney Australia Posts: 873	The other potential reason is that 19mb/s on the same area of tape gives you a wider track pitch and therefore less chance of droputs. Same reason Sony elected a higher tape speed for DV-Cam

November 4th, 2005, 07:04 AM	#6
Steve Crisdale Major Player Join Date: Jan 2004 Location: Katoomba NSW Australia Posts: 635	The answer to this appeared on this forum ages ago... so a search may not find it for you! The 19.3Mbit 720p data rate was based on the maximum Broadcast HD bit-rate. The 25Mbit data rate was based on the maximum data capacity of Mini-DV tape. Just a difference in philosophy, rather than some exotic conspiracy by megalomaniac corporate executives!!