Optimal bitrate setting

[pitsi]

I would like to convert .avi files that I have to DVD-R, for watching them on my television set.

I have succesfully done this in the past but what I am thinking now is this. Lets say we have the following file:

.avi
xvid
576x304
863Kb/s
97 mins

Isn't it a waste of space to use a whole DVD-R for this file? I mean the way I see it, the quality is not that good in order for it to need 4.3GB of space, even for a conversion to MPEG-2 format. So what I would like to know is, how many similar files could I put on a single DVD-R (4.3GB) without sacrificing the current quality of the video files that I have?

Thanks.

[bugster]

Experiment and find out for your self. There is no hard and fast rule. Perhaps a decent starting pint would be to trebble the xvid bitrate for the mpeg-2 and see if you are happy with the results. If you are, lower it a bit and try again. If not, increase it.
Remember though that whatever figure you come up with will be different for each encode you do).

[jimmalenko]

ahhh, welcome to the part where knowledge and experience come in. As bugster says, there is no hard and fast equation for this, but a good guide IMO would be 3X-4X your bitrate, so long as you choose the correct frame size.

[junkmalle]

MPEG 2 usually require 2 to 4 times the bitrate of MPEG 4.

[ZippyP.]

For your file a DVD-mpeg 352X480 @ 2500 Kbps would be OK.

[vhelp]

Also bare in mind, that your source you are capturing is another factor
to consider when determining quality.

If your source is Satellite or Digital Cable, chances are, it will have
MPEG macro blocks in them, (see Wresting programs) and when you encode
this source, (with these macro blocks) you will in addition, be adding
new macro blocks.., even if you raise the bitrate.

.. This is another reason why I don't like VBR (2pass) encoding, because
.. no matter high regid you fine-tune your 2 pass settings, there will
.. almost always be not enought coverage, and those macro blocks will
.. be there, smiling at'cha.
.
.. I realize that the majority for 2pass is space and filling a disk.
.. but, if these are 1 hr programs, I would have to say, another route
.. would probably be best.., specially for sports (not that it was mentioned
.. anywhere's here)

Also, to factor in and consider another facit of the equation.., w/ respect
to the above "commented" area.. that this issue w/ Encoder-dependant.
Weather it's a software; $$$; or hardware; not all algorithems are the same
So mileage will vary.

I would suggest that you start w/ a very high bitrate, and bump down, say
something in increments of around 1000 bitrate, until you notice macro blocks.
Course, if your source already has them (Satellite; Digital Cable) this will
be hard to find, unless you spot them *before* you encode them (say, inside
the AVI file itself)

-vhelp 2980

[Soopafresh]

Good point on the Macro Blocks. Man, I HATE 'em. That VirtualDub plugin from MSU (Deblocker) does an OK job of reducing the block appearance. You can frameserve from Vdub to the Mpeg encoder, and wait a day or two for the final result