What format to use when uploading from Panasonic GS-15 to computer

Panasonic GS15 w/ Nero:

I'm not sure, but it /seems/ as if uploading from my gs-15 in DV file format
is as "native" a way possible to not lose any frames or pixels.

Is this true? I'm interested in bulk uploading my tapes, one file per tape,
for later splitting and perhaps converting to mpg or burning on dvd.

If it should be DV, then should I use type-1 or type-2?

I'm afraid to chose the wrong format which might result in a
loss-compression being used, losing pixels I wouldn't able to get back.

What is the safest format to use? If I burn any to dvd, I'm assuming that
it would be best to burn in native DV format?

Thanks!

 

Thomas G. Marshall coughed up:

By this I mean, placing the DV format file itself onto a /data/ dvd.

 

Transfers from your camcorder will be a miniDV codec AVI -- these will be
lossless. However, unless you're interested only in archiving chunks no
larger than 20 minutes that will not play on a setup DVD box, you'll need to
transcode your AVI to mpeg2 and then author in proper format before burning
it to a DVD.

 

PTRAVEL coughed up:

Why 20 minutes? Because of huge files? Does this miniDV codec not do a
lossless compression?

 

20 minutes represents the maximum amount of uncompressed DV-codec AVI that
can be stored on a 4.7 Gb DVD. A double-layer DVD will hold slightly under
twice as much.

MiniDV is D-25 standard, which provides for roughly 5-to-1 compression of
the video signal. However, unlike mpeg, the D-25 standard does not do
temporal compression, i.e. each frame of a miniDV video stream contains the
complete information for that frame, albeit compressed 5-to-1. This allows
miniDV to be easily edited, unlike mpeg.

 

Exactly (well, sort of). The contents of the tape is compressed 5:1 by
the camera electronics, and the transfer to the PC over FireWire is
just a bit for bit copy to the computer. This is also true if you
transfer directly from the camera section without tape (e.g., analog
pass-through or WebCam style). The full video only exists temporarily
in the internal electronics.

Anyway, the resulting data takes up about 3.6 MBytes/sec or 13 GB per
hour, and the DVD holds only 4.37 GB (or 4.7 GB if you prefer 10^9
instead of 2^30 for a GB).

It would be a lot worse if the 5:1 compression wasn't there...

BTW, if you're using FAT32 instead of NTFS or a Unix file system,
individual files can't be over 4GB anyway - and not only that, some
software cuts this limit in half.

Gino

<SNIP the rest>

 

Gene E. Bloch coughed up:

Since the internal hoohah is not under my control, I don't really care.

But there *are* lossless compressions available for this version of AVI, no?

AH, *wait*. I think I understand what you are getting at. The 5:1
compression that is done by the camera is already a fully digital
compression and cannot be easily compressed further without loss. But that
all depends upon the algorithm used by that compression. For example, using
the LZ built into winzip can manage to squeeze an extra lossless 10% out of
compressions done by LZ of smaller bit width by other applications.

It's just that some people in this ng seem to imply that any compression at
all *necessitates* loss, and that is just not true in the digital world. It
may be an analog holdover.

Thanks.

But my next question is that Nero offers a multitude of AVI compressions,
should I decide to encode from the tape in AVI. Some of these compressions
are lossless, and might squeeze the (already 5:1) output a little better,
no?

Nah, NTFS. But the 4 gig to 2 gig thing is a very common problem: it
centers on software not regarding a 32 bit integer as unsigned. The
presense of that sign bit knocks the range of the integer in half. In this
day and age, nearly /everything/ should be using 64 bit integers anyway.


....[rip]...

 

Yes. Huffy is a lossless codec.

Almost. The 5:1 compression done by the camera results in loss. Howelver,
as you've surmised, it is done at the camera end, is part of the DV-25 spec,
and can't be by-passed.

LZ is particularly unsuited for video, which is one of the reasons why it
isn't used. It's highly unlikely you'll realize gains of as much as 10%
using it -- 1 or 2% is more likely.

You're right -- compression does not necessarily imply loss. However, in
the video world, for all practical purposes, it does.

If it's a true lossless compression and don't you care about the ability to
view the archived video directly, then in theory you're right. However, in
practice, lossless compressions will not gain very much.