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External Drives: 500 GB= ??? Hours of HD, SD?

Discussion in 'ViP612/622/722/722K DVR Support Forum' started by aaronbud, Aug 25, 2007.

  1. aaronbud

    aaronbud Legend

    Nov 3, 2006
    Sorry if this has been addressed before, but just how much HD content can you fit on a 500GB drive? How much SD? I am I right in assuming a 750GB drive will hold roughly 50% more HD content than a 500GB?

    thanks in advance for any info...
  2. pdxsam

    pdxsam Godfather

    Jun 19, 2004
    It depends on a few factors.

    MPeg4 vs. MPeg 2.

    How much motion or detail is in the recording.

    How much the baseline bitrate is for each channel.

    720 or 1080?

    So there's no way to make a blanket statement that 750GB would be 1/2 as much more storage
    as a 500GB it could be less or it could be more.
  3. Stewart Vernon

    Stewart Vernon Roving Reporter Staff Member Super Moderator DBSTalk Club

    Jan 7, 2005
    Kittrell, NC
    Actually, this is the only statement that can be made for sure. A 500GB drive has twice as much space as a 250GB drive. A 750GB drive has 50% more space than a 500GB drive. Those are simple mathematical facts.

    What is harder to quantify is how much extra time for HD or SD programs you will gain.. but on average, the math should still be the same unless you suddenly change your recording habits on the new drive vs what you have now.
  4. Stewart Vernon

    Stewart Vernon Roving Reporter Staff Member Super Moderator DBSTalk Club

    Jan 7, 2005
    Kittrell, NC
    To answer your initial question... The ViP622 comes with about 250GB of space... and for that we are quoted 30 HD hours and 200 SD hours... so one could infer from that a 500GB would be about 60 HD hours and 400 SD hours.

    Now... that "average" is likely a conservative estimate assuming 1080i HD at full resolution and acceptable quality bitrate with MPEG2 compression. Since Dish has some channels less than 1080i, and also there are 720p channels... the actual recording time could be slightly higher than 30 HD hours. Also, some programs compress more than others.

    OTA MPEG2 HD tends to take up the most space, with satellite HD following that. IF you record a lot of OTA HD, expect your HD time to be at or slightly below the quoted hours for the hard drive. If you record a lot of satellite HD, expect slightly higher.

    Now... with MPEG4, we are seeing somewhere between 1/4 and 1/2 space reduction in file sizes... so you could expect recording times of 25-50% higher recording an MPEG4 HD channel instead of MPEG2.

    It is a lot to take into consideration... so it is really hard to quantity with any real accuracy what the maximum HD space would be. SD is a little easier, since most of Dish SD is compressed in the same manner and all is in MPEG2... but even there it can vary depending on the type of programming.

    Basically... it is easier to figure minimum HD and SD times for a given amount of hard drive space than a maximum. There is a wide range now of how much time you can have given all of the variables in play.
  5. rtk

    rtk AllStar

    Apr 14, 2007
    The above answers are correct, there is no exact number.

    Based on current MPEG4 HD recordings, a reasonable estimate is ~2.5GB per hour of 1440x1080i MPEG4 content. That translates to ~40 Hours per 100GB of hard drive space for MPEG4 HD programming. For comparison purposes, MPEG2 1080i HD recordings were commonly ~4.5-5GB/hr.

    Which direction things go as the MPEG2 channels converted MPEG4 and new HD channels are added is anyones guess.
  6. aaronbud

    aaronbud Legend

    Nov 3, 2006

    Thank you that does clear it up abit.
  7. Hunter Green

    Hunter Green Legend

    May 8, 2006
    Is that before or after the space reserved for VoD and other DISH promotional stuff is removed? If it's 250G of our space plus some other space, then yes. But if the 622 has 250G gross space, we need an estimate for how much of that is reserved before we can make a good estimate.
  8. ChuckA

    ChuckA Hall Of Fame

    Feb 7, 2006
    I assume that is an estimate of the space for your recordings since the 622 has a 320 gig HDD.
  9. Ron Barry

    Ron Barry 622 Tips & Trick Keeper

    Dec 10, 2002
    If you look in the vip722 first look, Rob provides some number for size requirement for MPEG2 SD, MPEG2 HD, and MPEG4 HD. Using those numbers with the understanding that MPEG size compression can vary widely from show to show, I would figure on about 4GB per hour for HD. So on a 500GB Drive one would expect 125 hours of HD. Seems my calcs are along the lines of rtk and about twice as much as HDMes.

    Hmmm. Well one thing that anyone can do now with external USB support is do some more analysis of disk drive requirements since the size of the recorded show is shown instead of the time. Not sure if it is worth somebodies time but I believe that is what Rob did when he wrote up his first look and where those numbers came from. I used his numbers and figured on about a 50/50 split of MPEG4 and MPEG2 recordings.

    What is obvious here that these numbers, just like the estimate on the DVR screen, are subject to a large amount of error given the numerious variables surrounding this topic and the fact that VBR MPEG is used.
  10. jstachowiak

    jstachowiak New Member

    Oct 28, 2008
    Installed BlacX 2.5/3.5 SATA HDD USB Docking Station with Seagate 500GB Serial ATA HD 7200/32MB SATA $105 CompUSA. No problem hooking it into my VIP722.

    I moved several shows over to this setup from the 722's HD and discovered something interesting. The Dish shows were considerably smaller size than the OTA shows I recorded. One hour on Dish ranges from about 2500MB to 4600MB the same length show OTA took up to 7000MB.

    So far so good.

  11. puckwithahalo

    puckwithahalo Hall Of Fame

    Sep 2, 2007
    That's because the OTA is not compressed. Ot at least is at a lower compression rate.
  12. phrelin

    phrelin Hall Of Fame DBSTalk Club

    Jan 18, 2007
    All I know is that I get about 100-110 HD movies per 750GB EHD.
  13. Jeff_DML

    Jeff_DML Legend

    Feb 12, 2008
    OTA is compressed using MPEG2 codec. Most if not all DISH HD is compressed with AVC codec which is a newer and more efficient. Also DISH is more aggressive on the amount of compression they use.

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