Disadvantage to mpeg vs avi?

[CC]

Archived from groups: rec.video.desktop (More info?)

I had lots of home movies transferred to dvd-r (20 or so DVDs in AVI files)
but it was only 2 dvds once in was "condensed?" into mpeg for regular
playback in DVD players. I am also converting my Hi 8 tapes to dvd.

My question is this. Is there an advantage to having all these AVI file
dvd's lying around? Can't I go ahead and use the mpeg versions on the two
dvds to edit just as easily if I have the right software?

What am I losing the capability to do in editing if I use mpegs instead of
the voluminous avi's?

Thanks
Chris

 

[Guest]

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cc wrote:
> I had lots of home movies transferred to dvd-r (20 or so DVDs in AVI
> files) but it was only 2 dvds once in was "condensed?" into mpeg for
> regular playback in DVD players. I am also converting my Hi 8 tapes
> to dvd.
>
> My question is this. Is there an advantage to having all these AVI
> file dvd's lying around? Can't I go ahead and use the mpeg versions
> on the two dvds to edit just as easily if I have the right software?
>
> What am I losing the capability to do in editing if I use mpegs
> instead of the voluminous avi's?
>
> Thanks
> Chris


You'll be losing a lot of picture quality. Without getting technical, the
reason "20 or so DVDs in AVI files" is reduced to a mere 2 DVDs is because
of the amount of compression MPEG-2 does to those files. Also, any editing
you do with those mpeg-2 files will have to be recompressed again for DVD
authoring/burning resulting in further quality loss.

Mike

 

[CC]

Archived from groups: rec.video.desktop (More info?)

So, when I transfer from my Sony digital 8mm camcorder through firewire onto
a hard drive, its typically going into an avi file....
but when I transfer from that same camera to the Panasonic DVD recorder, the
DVD recorder is most likely converting the avi's to an mpeg, in order to
burn the dvd-r?

and, it sounds like mpeg files aren't "cleanly" editable? They always have
to be recompressed to be read again on a dvd player?

Chris

 

[Guest]

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cc wrote:
> So, when I transfer from my Sony digital 8mm camcorder through
> firewire onto a hard drive, its typically going into an avi file....
> but when I transfer from that same camera to the Panasonic DVD
> recorder, the DVD recorder is most likely converting the avi's to an
> mpeg, in order to burn the dvd-r?


When you transfer from camcorder to the Panasonic, that's exactly what it's
doing. In real-time, no less. I have no idea whether the image quality is
as good as using good editing/authoring/burning software but I haven't read
complaints on this NG yet.


> and, it sounds like mpeg files aren't "cleanly" editable?

Not very easily, no.

> They always
> have to be recompressed to be read again on a dvd player?

Yes, because you have to render them out as MPEG-2 files - again. Hence the
recompression.

Mike

 

[Guest]

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On Wed, 21 Apr 2004 01:11:52 GMT, "cc" <chaffin83@comcast.net> wrote:
>My question is this. Is there an advantage to having all these AVI file
>dvd's lying around? Can't I go ahead and use the mpeg versions on the two
>dvds to edit just as easily if I have the right software?
>
>What am I losing the capability to do in editing if I use mpegs instead of
>the voluminous avi's?

Read here - http://tangentsoft.net/video/mpeg/edit.html

Some software (not Premiere 6x) will edit mpg, other's won't


John Thomas Smith
http://www.direct2usales.com
http://www.pacifier.com/~jtsmith

 

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cc wrote:

>
> it sounds like mpeg files aren't "cleanly" editable? They always have
> to be recompressed to be read again on a dvd player?
>
>

Not necessarily. It depends on how you want to edit, and it depends on if the
mpeg-2 files are already DVD compliant.

If you're doing cuits-only, then no recomprerssion is needed, and you can do it
frame-accurately, and maintain audio sync.

I use "Mpeg-VCR" from www.womble.com to do this on the mpeg-2 files that my
PVR-250 card creates. I've edited a three hour file without any sync issues.

The Womble Mpeg-VCR can output an edited 45 minute file in about 5 minutes, so I
know it's not doping any recompression.

One caveat though - this only works if your files are encoded with CBR (constant
bit rate). If you use VBR, then all bets are off.

As for AVI - it all depends on the codec. If your AVI file is using a VBR mpeg-4
codec, like Divx, then you'll have issues trying to edit it, so there's nothing
magical about "AVI" solving any problems - it all depends on the codec.

Keith

 

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On Wed, 21 Apr 2004 03:01:38 GMT, "cc" <chaffin83@comcast.net> wrote:

>mpeg files aren't "cleanly" editable?

If you only need cutting them, and you do not mind cutting only on
keyframes, then it is 100% clean. If you need to cut on any frame,
then a very few of the frames need to be reencoded (say, 8-9 average
for a DVD standard), while the rest need no reencoding at all. I would
call that 99% clean, but ymmv.

 

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"Bariloche" <bariloche@bariloche.com> wrote in message
news:blsc80pd5bot93ahbqn18jvrhp9m304t7b@4ax.com...
> On Wed, 21 Apr 2004 03:01:38 GMT, "cc" <chaffin83@comcast.net> wrote:
>
> >mpeg files aren't "cleanly" editable?
>
> If you only need cutting them, and you do not mind cutting only on
> keyframes, then it is 100% clean. If you need to cut on any frame,
> then a very few of the frames need to be reencoded (say, 8-9 average
> for a DVD standard), while the rest need no reencoding at all. I would
> call that 99% clean, but ymmv.

Well put. "Bariloche".

CC;
Do you live on a small sailboat? Or even a Chris-Craft?
20 DVDs fit on 2.5 pages in a 3 ring binder. I have all 7
Seasons of "Buffy the Vampire Slayer" on 3.5 pages.
12 pages fit in a 1" binder that's 96 DVDs. I don't throw
away empty peanut butter jars, because I just might be
able to use them someday. Keep the AVI DVDs, you
seem like someone who would actually be able to find
them if you needed them at some later date.

Luck;
Ken

 

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On Wed, 21 Apr 2004 11:46:57 GMT, Keith Clark
<clarkphotography@hotmail.com> wrote:

>One caveat though - this only works if your files are encoded with CBR (constant
>bit rate). If you use VBR, then all bets are off.

What? I cannot see how the bitrate mode does a difference.

(BTW, Keith: I ascertained that the "Full sequence scan" setting in
MpegVcr does really screw it all.)

>As for AVI - it all depends on the codec. If your AVI file is using a VBR mpeg-4
>codec, like Divx, then you'll have issues trying to edit it, so there's nothing
>magical about "AVI" solving any problems - it all depends on the codec.

Generally speaking, AVI is better because there is lots more software
for it than for mpeg, and because you have an assortment of codecs,
from I-frame only (Mjpeg, for instance) to lossless (Huffyuv). Thus,
DivX inherently poses very much the same editing problems as mpeg, but
you have better tools to solve them.

 

[Guest]

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Bariloche wrote:

> On Wed, 21 Apr 2004 11:46:57 GMT, Keith Clark
> <clarkphotography@hotmail.com> wrote:
>
> >One caveat though - this only works if your files are encoded with CBR (constant
> >bit rate). If you use VBR, then all bets are off.
>
> What? I cannot see how the bitrate mode does a difference.
>

My experience with VBR is that when you make cuts to a VBR encoded file (or in many
cases simply convert it to Xvid with *no* cuts, then the audio gets hopelessly out of
sync.

CBR avoids that. I've read lots of posts on the www.snapstream.com site to suggest
that lots of people run into that also.

I set my PVR-250 to record in CBR only and I have no trouble doing edits.



>
> (BTW, Keith: I ascertained that the "Full sequence scan" setting in
> MpegVcr does really screw it all.)
>

Cool! So I'm not crazy... (at least not in regard to that, LOL!)


>
> >As for AVI - it all depends on the codec. If your AVI file is using a VBR mpeg-4
> >codec, like Divx, then you'll have issues trying to edit it, so there's nothing
> >magical about "AVI" solving any problems - it all depends on the codec.
>
> Generally speaking, AVI is better because there is lots more software
> for it than for mpeg, and because you have an assortment of codecs,
> from I-frame only (Mjpeg, for instance) to lossless (Huffyuv). Thus,
> DivX inherently poses very much the same editing problems as mpeg, but
> you have better tools to solve them.

OK, agreed.

However I haven't found anything that can do frame accurate cuts to Divx files and
maintain audio sync. Have you?

Keith