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  1. Hi pretty new to video, so please pardon if this question has been asked before. I am converting all my Digital 8 and Mini DV tapes into DV Avi files. I am just wondering that with the newer technology what is a more efficient format (storage vs quality) to archive this files? Please consider in later future I might want to do some edits on this files.

    is H264 better? I've seen that newer DSLR cameras like GH3 is using MOV with H264. Will this be a good format to convert? Any help would be appreciated.
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  2. Member Cornucopia's Avatar
    Join Date: Oct 2001
    Location: Deep in the Heart of Texas
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    For BEST quality, you want to retain in its original format. Digital8 and DV tapes' original format is DV.

    There may be other more efficient formats (incl. especially h.264), but with conversion to lossy formats is some loss of quality. You'll have to decide if it's worth it.

    Personally, DV's 25Mbps (aka ~13GB/hour) is not a huge space waster in today's TB+ HDD world. Plus, DV is inherently I-frame only, making it easy to edit. Many of those other more efficient codecs are precisely more efficient BECAUSE they are not I-frame only (making them harder to edit).

    Scott
    "When will the rhetorical questions end?!" - George Carlin
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  3. Thanks for the info. Sorry if it sounds stupid. how did you compute 13GB/hr from 25 Mbps. Is that formula will be how you compute storage requirement for the DSLR cameras?

    Like GH3 has a 50mbps H264 format, will that mean it will take approximately 50GB/hr?

    If you point me to a website that discusses this it will also be helpful.

    Thanks
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    Originally Posted by hongning View Post
    how did you compute 13GB/hr from 25 Mbps. Is that formula will be how you compute storage requirement for the DSLR cameras?
    A long time ago someone did that calculation. For many (most) of us DV=13GB/hr is like reciting the alphabet. We've said it so many time we just know. Memorize this one too, Filesize=Bitrate * Time.

    The DSLR question is less straightforward. Depending on the camera, the actual bitrate will depend on the complexity of the content. The figure cited by the manufacturer is approximate.
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  5. Well I just looked at the manual the 50 Mbits setting saves to an 8GB SD in 20 minutes Thus its 24GB/hr, the 74Mbits is about 34GB/hr. In that respect DIV Avi is a lot smaller. I will keep it as AVI.

    Thanks for all the help
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    Originally Posted by hongning View Post
    Well I just looked at the manual the 50 Mbits setting saves to an 8GB SD in 20 minutes Thus its 24GB/hr, the 74Mbits is about 34GB/hr. In that respect DIV Avi is a lot smaller. I will keep it as AVI.
    Let's make sure we're on the same page here. DV should be saved as DV, H.264 from a camera should also be archived in its original state with the card structure intact. (I've heard of DV50, but your 74 number is making me nervous -- where is that coming from, which manual?)
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  7. Okay maybe I was misquoting, but here is the specs of the camera

    Panasonic GH3
    MOV (H.264) resolution, frame and bit rates
    Option 1: 1920x1080 (60p): 50Mbps
    Option 2: 1920x1080 (30p): 72Mbps (All-I)
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  8. Member solarfox's Avatar
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    Originally Posted by hongning View Post
    Okay maybe I was misquoting, but here is the specs of the camera

    Panasonic GH3
    MOV (H.264) resolution, frame and bit rates
    Option 1: 1920x1080 (60p): 50Mbps
    Option 2: 1920x1080 (30p): 72Mbps (All-I)
    "Option 2" is the one most comparable to the DV format used by your Digital-8 and MiniDV cameras, because it's an "all I-frame" format; in other words, each frame of video is stored in its entirety as a JPEG-like image. Formats like MPEG, h.264, etc. rely on only storing some frames as I-frames, followed by a string of frames in which the encoder tries to predict what the next frame will look like, then only actually stores the differences between its predictions and what the next frame actually does look like, if those differences are greater than a certain limit. (Higher compression is then achieved by allowing greater "error" between prediction and reality.)

    However, the reason the "Option 2" h.264 files coming out of the camera are so much larger than the DV files, even when both are using all I-frames, is because of the higher resolution of the frames themselves. DV is 720x480, which is about 1/6th the number of pixels. Assuming that the file sizes scale linearly with increasing pixel count (which it probably doesn't, but let's just pretend it does for purposes of illustration), DV would require about 150Mbit/sec to encode the same resolution as that HD camera, whereas the camera's h.264 codec might get the 720x480 job done in approx. 12Mbit/sec instead of 25.

    So, all else being equal, you might get a smaller filesize out of the Option-2 h.264 if you captured the 720x480 video that way -- but of course, all else is not equal, because as smrpix says, the video on those Digital8 and MiniDV tapes is already compressed in DV format, so capturing or converting to h.264 will involve recompression, which will inevitably result in some quality loss. Given how cheap terabyte-size drives are, there's no real reason not to just keep the video in its native format as DV for archiving and editing.
    Last edited by solarfox; 21st Aug 2014 at 17:49.
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  9. DV AVI is closer to 30,000,000 bits per second including video, audio (type 2), and AVI overhead, 1 hour = 3600 seconds. So for 1 hour of DV AVI:

    file size = bitrate * running time
    file size = 30,000,000 bits per second * 3600 seconds
    file size = 108,000,000,000 bits
    file size = 13,500,000,000 bytes (8 bits per byte)
    file size = 13.5 billion bytes
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