[mythtv-users] I may have SOLVED the 5C cable encryption - DOH!
Michael T. Dean
mtdean at thirdcontact.com
Thu May 10 20:26:56 UTC 2007
On 05/10/2007 03:54 PM, Chad wrote:
> On 5/9/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
>
>> On 05/09/2007 02:23 PM, Asher wrote:
>>
>>> AFAIK DV is very large, it is what is used on digital camcorders.
>>>
>> IIRC, about 11GB/hr for NTSC at 720x480, but that's what transcoding is
>> for. :)
> Capturing from my camcorder yields much more than that. The DV files
> that dvgrab produces from the firewire port (that my camcorder is
> attached to) are about 2GB/min. From a ~10 minute capture the file is
> ~25GB.
True DV video uses a fixed bitrate of 25.146Mb/sec and audio uses
1.536Mb/sec. This works out to a minimum of 11.2GiB/hr. When you add
in subcode data, error detection, and error correction (about
8.7Mb/sec), you can go as high as 35.4Mb/sec (14.8GiB/hr). But, the
~11GB/hr is the smallest you'll go for a video and audio stream in DV
format.
DV50 doubles the bitrate of the video, and there are HD formats and
other variants, too. (HDV, ProHD and a bunch more about which I know
absolutely nothing.)
So, your camera probably uses a different format (variant of DV) that it
generically calls "DV". If the device the OP mentioned does, too, then
the video will take more room than the ~11GB/hr I quoted. But, since,
IMHO, 11GB/hr is /way/ too large for 720x480 video, that only supports
Asher's and my assertion that DV video would be huge.
This page has a pretty good comparison of sizes of various formats.
http://www.digitalservicestation.com/tips_tricks.html
Mike
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