• Blackmagic Design

  Data Rate for 1080i@25fps JPEG

  Posted by Alister Robbie on August 10, 2005 at 3:14 am

  Hi,

  Has anyone had a play with using the JPEG preset for capture / editing? I am keen to find out what kind of data rates this reduces the HD stream to. The idea is to do an initial capture of footage for a feature using the JPEG preset (so that it can be offlined on a slower machine) then capture only the necessary footage for onlining.

  Cheers

  Alister

  Luke Maslen replied 21 years, 1 month ago 2 Members · 3 Replies
• 3 Replies

• 

  Luke Maslen

  August 10, 2005 at 6:25 am

  Hi Alister,

  JPEG is a variable rate codec so it’s hard to give you a good number. However a test I have run was around 3.7 MB/sec compared with 14.5 MB/sec for DVCPRO HD. Having said that, DVCPRO HD quality is awesome and it also supports RT Extreme effects compared with JPEG in HD which looks good but not as good and which does not support RT Extreme. You can capture and play back JPEG and DVCPRO HD to a single drive using a dual-processor G5 with PCI-X. My 3G iPod is just fast enough to handle HD1080i/50 capture and playback which is just incredible given the quality. I would never use the iPod for serious DVCPRO HD work as it is only 4200 rpm whereas any decent Firewire drive should be 7200 rpm and be plenty fast enough for use with either JPEG or DVCPRO HD.

  BTW, apparently there was a magazine article stating that you could use DeckLink HD series cards to capture HD1080 video to an iPod in the DVCPRO HD format. I’d just like to refute the claim that the iPod in question was loaded with bad quality 70’s rock… It was great rock 😉

  Regards,

  Luke Maslen
  Blackmagic Design
• 

  Alister Robbie

  August 10, 2005 at 6:44 am

  Hi Luke,

  Thanks for the prompt response. The source footage is coming from HD-CAM, and I am looking at the most efficient way of creating a set of offline quality footage for doing the offline edit.

  I have been focussing on the HD JPEG compression because i believe that the board can capture to the HD JPEG format in real time. Will the Decklink HD board capture from the HD-SDI input to the DVC-PRO HD Codec in realtime?

  Out of interest, will the board do real-time down-conversion of the incoming stream? ie. HD signal coming in, captured as SD in realtime? This could be another option as it keeps the data rates and storage requirements down.

  Thanks

  Alister
• 

  Luke Maslen

  August 11, 2005 at 6:39 am

  Hi Alister,

  [Alister Robbie] “Will the Decklink HD board capture from the HD-SDI input to the DVC-PRO HD Codec in realtime?”

  Yes, this works fine in real time as does playback of DVCPRO HD. DVCPRO HD supports RT Extreme effects which may be something you will need.

  [Alister Robbie] “will the board do real-time down-conversion of the incoming stream?”

  Yes, any of our DeckLink HD series of cards will do this assuming you are working with a NTSC, NTSC 23.98 or PAL-compatible frame rate. This would be another option for you although DVCPRO HD will provide you with much more detail and you won’t have to worry about correct aspect ratios when moving between SD and HD.

  Regards,

  Luke Maslen
  Blackmagic Design

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