Archived from groups: rec.video.desktop (
More info?)
"Craig" <cviolette@prexar.com> wrote in message
news:9f181686.0411270625.938eeb@posting.google.com...
> "Ken Maltby" <kmaltby@sbcglobal.net> wrote in message
> news:<-b-dnfOu5ccdZjrcRVn-og@giganews.com>...
>> "Craig" <cviolette@prexar.com> wrote in message
>> news:9f181686.0411261546.1368fc1b@posting.google.com...
>> > I'm looking for a bitrate calculator that will calculate multiple
>> > video files to put on one dvd-r. If anyone has a spreadsheet that
>> > will do this type of calculation and would be willing to share it, I
>> > would be very grateful.
>> >
>> > Craig
>>
>> The free "Aspect"
http://aspect.fre3.com has a bitrate
>> calculator that will let you enter a custom target size.
>>
>> Luck;
>> Ken
>
>
>
>
> Ken, I use TMPGEnc and within this I compress with Constant Quality, I
> don't use CBR or VBR. The problem I have is that some files may be 15
> minutes long and some can be 2 hours long. I may even have 4 or 5
> files that are of various lengths. Normally when you use the
> calculators that are out on the internet, it assumes that you are only
> going to compress one file for the total length of the DVD, but in my
> case, it is different, because I want to be able to calculate the best
> possible size in order to get the best quality picture.
>
> Craig
Constant Quality (CQ) is a form of VBR encoding. You could
look at your disk as being able to store "X" amount of minutes, at
"Y" Quality of video, normally or on the average. Depending on
the mature of any piece of video, in order to maintain a "Constant
Quality", your encoder will vary the Bitrate. For instance I have a
hardware encoder that uses a CQ method for its VBR but instead
of having % settings I have to set a bit rate and a peak bit rate. I am
encoding to 352x480 at 6Mbps with a peak of 8Mbps as my settings
but the actual bitrate of the resulting video averages closer to 2Mbps.
My resulting file sizes vary greatly, with 43min clips ranging from
~500megs to over 800megs but they will average out so that six such
clips will fit on a DVD 99% of the time. (In fact with one source [the
Star Trek DS9 Series] seven 42min clips are fitting, using those same
settings.)
So, as you can see the content of your video will have an impact
on the bitrate used at any point in time by the QC VBR process.
This is a good thing by the way, matching the bitrate used to what
is needed allows the smallest files for any given quality video. This
compression is the whole reason for MPEG in the first place. You
can use CBR which would allow you to predict the exact size of
your files but you would have to compromise in size or quality.
There may be some good calculators out there that can do CQ
but I haven't run across any. What I would do in your case is to
establish the total "Duration (h:mm:ss)" that you wish to put on
your DVD, add up the time of each clip going on that particular
DVD. Then using a bitrate calculator enter that "Duration" and
4438 for the "Output Size, MB". ( "Aspect" was designed for
use with CDs, so it won't properly handle ratios that result in the
very high [~4Mbps and up] bitrates that can be used with DVDs
try 4238 with 2:30:00 for instance)
Once you have established a good reference bitrate for a full
DVD at an acceptable Quality, you can up the bitrate if you
find that you have less duration to put on your DVD. Conversely,
you need to fit a little more you have some idea of how much to
lower the bitrate. Changing bitrates in a CQ environment is a
little tricky and often, for the adjustments to have any effect, they
must cross certain undocumented points. Going from 4000kbps
to 4050 might have no effect but 4051 might.
Whatever bitrate the calculator comes up with will only be a
reference point that you can use to estimate the best settings for
your CQ VBR Encoding.
Luck;
Ken
Facebook
Twitter
Instagram