Panasonic PV-GS15 SD Card layout

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ps56k - 04 May 2008 20:20 GMT

at my wife's work., they have a Panasonic PV-GS15 camcorder.
It uses DV for the video, and has a SD Card for still photos.

In connecting the camcorder to her laptop,
and looking at photos (the card was full)
it was supposed to be a 8MB card,
but a right-click properties showed 6.45MB ???

The layout was like this :
\dcim -> the normal photos were here
\misc ???
\private\vtf\title ???

I wonder if the other sub-dirs were for special things the camera could do
??
They were empty -
SO - if the card should be seen as 8MB, and is only showing 6.45MB,
then where is the rest of it going ????

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Gene S. Berkowitz - 05 May 2008 00:10 GMT

> at my wife's work., they have a Panasonic PV-GS15 camcorder.
> It uses DV for the video, and has a SD Card for still photos.
[quoted text clipped - 14 lines]
> SO - if the card should be seen as 8MB, and is only showing 6.45MB,
> then where is the rest of it going ????

To "sector slop". Any FAT formatted card requires a minimum of one
sector (512 bytes) to store ANYTHING, even a single byte of information.
The cluster size (minimum number of sectors allocated to store anything)
could be more than one sector, which makes the slop even worse.

If you're ambitious, you could take each file's reported size, then
round up to the nearest multiple of 512. You'll get closer to 8 MB.
There's also two copies of the FAT table, and space reserved for the
root directory (with every directory entry requiring 32 bytes).

Also, though it is unlikely, there can be hidden files and directories
on the card, that you might not be seeing.

--Gene

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Jürgen Exner - 05 May 2008 01:20 GMT

>In connecting the camcorder to her laptop,
>and looking at photos (the card was full)
>it was supposed to be a 8MB card,

8MB? This card must be truly ancient. Today cards with 1000 times the
capacity are readily available for little money.

>but a right-click properties showed 6.45MB ???

Showing 6.45MB of _WHAT_? Total capacity? Used space? Available space on
an empty drive? Total data on drive? All those numbers mean something
different and will be different.

>SO - if the card should be seen as 8MB, and is only showing 6.45MB,
>then where is the rest of it going ????

Many different possibilities, depending upon _WHAT_ number those 6.45MB
are actually referring to:
- file system was created with a smaller capacity
- file system overhead; any file system requires some space to store its
own meta information like e.g. directory information, free sector list,
etc.
- cluster loss due to large cluster sizes. This can be particularly bad
on a small drive like that when you choose a large cluster size.
Remember, on average the last cluster of each file will be half empty.
I.e. if you choose a cluster size of 32kB then you are loosing 16kB per
file on average
- difference between decimal and binary MB, i.e. between 8x1.000.000
byte and 8x2^20 (=8x1.048.576 = 8388608) byte.
- you misinterpreted the numbers
- ...

jue

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