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November 1st, 2005, 03:34 PM
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#1 |
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Regular Crew
Join Date: Mar 2005
Location: Berlin, Federal Republic of Germany
Posts: 109
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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?
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November 1st, 2005, 06:05 PM
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#2 |
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Major Player
Join Date: Jul 2003
Location: North Ridgeville, Ohio
Posts: 407
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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.
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Dave |
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November 2nd, 2005, 02:23 PM
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#3 |
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Major Player
Join Date: Jul 2004
Location: Los Angeles, CA
Posts: 327
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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...
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Matt Irwin DP / matt.irwincine.com |
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November 2nd, 2005, 03:55 PM
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#4 |
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Major Player
Join Date: Jun 2005
Location: Houston, TX
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The bandwidth of DVHS is 28.2 Mbps, not 19.3...
SONY probably just booby-trapped their cameras. |
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November 3rd, 2005, 03:32 AM
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#5 |
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Contributor
Join Date: Jul 2005
Location: Sydney Australia
Posts: 873
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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 |
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November 4th, 2005, 07:04 AM
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#6 |
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Major Player
Join Date: Jan 2004
Location: Katoomba NSW Australia
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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!! |
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November 6th, 2005, 03:28 PM
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#7 | |
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Regular Crew
Join Date: Nov 2003
Location: New England
Posts: 195
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Quote:
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November 7th, 2005, 01:11 AM
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#8 |
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Trustee
Join Date: Aug 2003
Location: Vancouver BC Canada
Posts: 1,315
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"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.
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Damnit Jim, I'm a film maker not a sysytems tech. |
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