HD Record Length To Hard Drive Size

Discussion in 'TiVo Series3 HDTV DVRs' started by Status, Aug 31, 2007.

  1. Status

    Status New Member

    29
    1
    Jul 11, 2007
    Seattle, Wa

    Advertisements

    Anyone have an approximate conversion chart for equating hard drive size to hours of High Def recording?

    Eg, Standard HD sizes = 250gig, 320 gig, 400 gig, 500gig and 750 gig...and how many hours of High-Def they will record?

    Thinking about upgrading my TivoHD and debating if I want to wait for the eSATA enabling or if I want o just replace the hard drive.

    Any timeframe on the eSATA port enabling for the TivoHD?

    -Status
     
  2. Chimpware

    Chimpware New Member

    334
    0
    Jan 30, 2002
    Be nice if Tivo also added NAS access possibly with UPnP...
     
  3. lickwid

    lickwid Member

    102
    1
    Oct 2, 2005
    SF Bay Area, CA
    I believe it's about 8GB of Hard Drive space per Hour of recorded HD Content. This is approximate. I believe my 1.0TB drive can do up to 129 hours of HD Content.
     
  4. mikeyts

    mikeyts Stream Warrior

    2,422
    5
    Jul 10, 2004
    San Diego,...

    Advertisements

    Recording time in HD is fairly easy to calculate, provided you make some kind of assumption as to the bit rate of the content, which will vary from channel to channel. Locally, over-the-air broadcast bit rates seem to vary from about 15 Mbps to 18.5 Mbps and the highest bit rate HD cable channel broadcasts (ESPN, HDNet, TNT, etc) average around 18.5 Mbps. Using 18 Mbps, we get:

    18 * 3600 seconds-per-hour = 64800 Mbits-per-hour / 8590 Mbits-per-GB = 7.54 GB-per-hour

    Note that that calculation assumes 2-to-the-30th bytes-per-GB, which is how engineers working with computers would think of GB (and what computer software--like TiVo's recording info dialog--means when it gives figures in GB). Marketing people mean 1 billion (10-to-the-9th) bytes when they say GB, so a drive marked 500GB on the package is actually around 465 computing GB (I say "around" because marketers tend to round up :rolleyes: ). In marketing terms, 18 Mbps content consumes 8.1 billion-bytes-per-hour, so a 500GB drive would hold a bit over 61 hours of it.
     
  5. pkscout

    pkscout Well-Known Member

    4,009
    43
    Jan 10, 2003
    Honolulu, HI
    That only accounts for the video and doesn't include stuff like the multiple audio and closed captioning (yes, I know cc isn't that huge). 8 - 9 gb/hour is a better, more conservative estimate.
     
  6. mikeyts

    mikeyts Stream Warrior

    2,422
    5
    Jul 10, 2004
    San Diego,...
    How do you figure? It accounts for the entire stream as recorded.
     
  7. Status

    Status New Member

    29
    1
    Jul 11, 2007
    Seattle, Wa
    Yes, I'd agree, would be nice if Tivo supported NAS and UPnP...and DiVx (networked, not hosted through TivoDesktop).

    I'd agree, HD content is hard to estimate. 480i is significantly different then 1080p/120Hz, but was just going for a general guess/estimate and sounds like 8gig/hour is a reasonable guess.

    Thanks!

    -Status
     

Share This Page

spam firewall

Advertisements