Compression parameter settings



WMMuser
07-09-2005, 10:33 PM
Hi,
I'm just getting into video and DVD terminolgy etc. and am having difficulty
finding reference to the effect of various compressing parameters.
I use TMPGEnc to compress mpg files to a size that will fit onto a DVD, and
following the "Help" suggestion I use CQ in the rate control mode, this gives
me various parameters to set for the compression routine.
I am trying to understand the effect of these settings, so ran a series of
test compressions leaving the min. bit rate at 0, not enableing the padding
minimium, and leaving the spoilage parameters at the default setting of 0 on
P pics and 20 on B pics. I then compressed the same mpg file using quality
100, 80, and 60 against a maximum bit rate of 8000, 7000, 6000 and 5000 and
noted the resulting file size as a percentage of the original. This gave me
some indication of the size reduction I could achieve using these parameters.
My questions are,
1) Should I reduce the quality in preference to the bit rate, or reduce the
bit rate and leave the quality as high as possible, or reduce them both in
proportion to achieve the percentage size reduction I require?
2) Is there a minimium value of quality or bit rate I should avoid going
below as it will noticably reduce the resulting video quality?
3) Should I start fiddling with the other parameter settings?
Sorry this is so long, but I thought it best to give all the relevant
details of my problem
Thank for any help posted

PapaJohn \(MVP\)
07-09-2005, 10:33 PM
Google the term 'bit budgeting' and check a few places like this one:

http://www.scheif.net/DVDAuthoring/DVDBitBudgeting.html

--
PapaJohn

Movie Maker 2 and Photo Story 3 - www.papajohn.org
Photo Story 2 - www.photostory.papajohn.org
..
"WMMuser" <WMMuser@discussions.microsoft.com> wrote in message
news:88EA77E2-4FFA-4B91-A04B-FD71C3E7C357@microsoft.com...
> Hi,
> I'm just getting into video and DVD terminolgy etc. and am having
> difficulty
> finding reference to the effect of various compressing parameters.
> I use TMPGEnc to compress mpg files to a size that will fit onto a DVD,
> and
> following the "Help" suggestion I use CQ in the rate control mode, this
> gives
> me various parameters to set for the compression routine.
> I am trying to understand the effect of these settings, so ran a series of
> test compressions leaving the min. bit rate at 0, not enableing the
> padding
> minimium, and leaving the spoilage parameters at the default setting of 0
> on
> P pics and 20 on B pics. I then compressed the same mpg file using quality
> 100, 80, and 60 against a maximum bit rate of 8000, 7000, 6000 and 5000
> and
> noted the resulting file size as a percentage of the original. This gave
> me
> some indication of the size reduction I could achieve using these
> parameters.
> My questions are,
> 1) Should I reduce the quality in preference to the bit rate, or reduce
> the
> bit rate and leave the quality as high as possible, or reduce them both in
> proportion to achieve the percentage size reduction I require?
> 2) Is there a minimium value of quality or bit rate I should avoid going
> below as it will noticably reduce the resulting video quality?
> 3) Should I start fiddling with the other parameter settings?
> Sorry this is so long, but I thought it best to give all the relevant
> details of my problem
> Thank for any help posted

WMMuser
07-09-2005, 10:33 PM
Thanks for the link PapaJohn, this lets me work out time against a fixed
bitrate, but can I assume that if I have a max of 8000 and a min of 0 the
average is 4000, should I even be using a 0 min bit rate, what is the effect
of the enable padding not to be below min bit rate, what does the Quality
parameter in TMPGEnc do, and what do the other P and B picture spoilage
parameters do?

"PapaJohn (MVP)" wrote:

> Google the term 'bit budgeting' and check a few places like this one:
>
> http://www.scheif.net/DVDAuthoring/DVDBitBudgeting.html
>
> --
> PapaJohn
>
> Movie Maker 2 and Photo Story 3 - www.papajohn.org
> Photo Story 2 - www.photostory.papajohn.org
> ..
> "WMMuser" <WMMuser@discussions.microsoft.com> wrote in message
> news:88EA77E2-4FFA-4B91-A04B-FD71C3E7C357@microsoft.com...
> > Hi,
> > I'm just getting into video and DVD terminolgy etc. and am having
> > difficulty
> > finding reference to the effect of various compressing parameters.
> > I use TMPGEnc to compress mpg files to a size that will fit onto a DVD,
> > and
> > following the "Help" suggestion I use CQ in the rate control mode, this
> > gives
> > me various parameters to set for the compression routine.
> > I am trying to understand the effect of these settings, so ran a series of
> > test compressions leaving the min. bit rate at 0, not enableing the
> > padding
> > minimium, and leaving the spoilage parameters at the default setting of 0
> > on
> > P pics and 20 on B pics. I then compressed the same mpg file using quality
> > 100, 80, and 60 against a maximum bit rate of 8000, 7000, 6000 and 5000
> > and
> > noted the resulting file size as a percentage of the original. This gave
> > me
> > some indication of the size reduction I could achieve using these
> > parameters.
> > My questions are,
> > 1) Should I reduce the quality in preference to the bit rate, or reduce
> > the
> > bit rate and leave the quality as high as possible, or reduce them both in
> > proportion to achieve the percentage size reduction I require?
> > 2) Is there a minimium value of quality or bit rate I should avoid going
> > below as it will noticably reduce the resulting video quality?
> > 3) Should I start fiddling with the other parameter settings?
> > Sorry this is so long, but I thought it best to give all the relevant
> > details of my problem
> > Thank for any help posted
>
>
>

Graham Hughes
07-09-2005, 10:33 PM
0 min and 8,000 max does not give an average of 4,000.
Setting a CBR of 4,000 does not give a bitrate constantly of 4,000, as it is
only an average taken over so many seconds adn if I could remember how many
I'd say :)
Have a read of this to help in understanding GOPs and IBP frames.
http://www.simplydv.co.uk/simplyBB/viewtopic.php?t=7704

--
Graham Hughes
MVP Digital Media
www.myvideoproblems.co.uk
www.dvds2treasure.com
www.simplydv.com


"WMMuser" <WMMuser@discussions.microsoft.com> wrote in message
news:F4119A9E-4753-4C48-AA3F-88C41994F860@microsoft.com...
> Thanks for the link PapaJohn, this lets me work out time against a fixed
> bitrate, but can I assume that if I have a max of 8000 and a min of 0 the
> average is 4000, should I even be using a 0 min bit rate, what is the
> effect
> of the enable padding not to be below min bit rate, what does the Quality
> parameter in TMPGEnc do, and what do the other P and B picture spoilage
> parameters do?
>
> "PapaJohn (MVP)" wrote:
>
>> Google the term 'bit budgeting' and check a few places like this one:
>>
>> http://www.scheif.net/DVDAuthoring/DVDBitBudgeting.html
>>
>> --
>> PapaJohn
>>
>> Movie Maker 2 and Photo Story 3 - www.papajohn.org
>> Photo Story 2 - www.photostory.papajohn.org
>> ..
>> "WMMuser" <WMMuser@discussions.microsoft.com> wrote in message
>> news:88EA77E2-4FFA-4B91-A04B-FD71C3E7C357@microsoft.com...
>> > Hi,
>> > I'm just getting into video and DVD terminolgy etc. and am having
>> > difficulty
>> > finding reference to the effect of various compressing parameters.
>> > I use TMPGEnc to compress mpg files to a size that will fit onto a DVD,
>> > and
>> > following the "Help" suggestion I use CQ in the rate control mode, this
>> > gives
>> > me various parameters to set for the compression routine.
>> > I am trying to understand the effect of these settings, so ran a series
>> > of
>> > test compressions leaving the min. bit rate at 0, not enableing the
>> > padding
>> > minimium, and leaving the spoilage parameters at the default setting of
>> > 0
>> > on
>> > P pics and 20 on B pics. I then compressed the same mpg file using
>> > quality
>> > 100, 80, and 60 against a maximum bit rate of 8000, 7000, 6000 and 5000
>> > and
>> > noted the resulting file size as a percentage of the original. This
>> > gave
>> > me
>> > some indication of the size reduction I could achieve using these
>> > parameters.
>> > My questions are,
>> > 1) Should I reduce the quality in preference to the bit rate, or reduce
>> > the
>> > bit rate and leave the quality as high as possible, or reduce them both
>> > in
>> > proportion to achieve the percentage size reduction I require?
>> > 2) Is there a minimium value of quality or bit rate I should avoid
>> > going
>> > below as it will noticably reduce the resulting video quality?
>> > 3) Should I start fiddling with the other parameter settings?
>> > Sorry this is so long, but I thought it best to give all the relevant
>> > details of my problem
>> > Thank for any help posted
>>
>>
>>

nupac
07-09-2005, 10:36 PM
I am trying to compress video to put on my website, I am sure I used Windows
Movie maker to do this on a previkous occasion but have forgotten how can you
help

"PapaJohn (MVP)" wrote:

> Google the term 'bit budgeting' and check a few places like this one:
>
> http://www.scheif.net/DVDAuthoring/DVDBitBudgeting.html
>
> --
> PapaJohn
>
> Movie Maker 2 and Photo Story 3 - www.papajohn.org
> Photo Story 2 - www.photostory.papajohn.org
> ..
> "WMMuser" <WMMuser@discussions.microsoft.com> wrote in message
> news:88EA77E2-4FFA-4B91-A04B-FD71C3E7C357@microsoft.com...
> > Hi,
> > I'm just getting into video and DVD terminolgy etc. and am having
> > difficulty
> > finding reference to the effect of various compressing parameters.
> > I use TMPGEnc to compress mpg files to a size that will fit onto a DVD,
> > and
> > following the "Help" suggestion I use CQ in the rate control mode, this
> > gives
> > me various parameters to set for the compression routine.
> > I am trying to understand the effect of these settings, so ran a series of
> > test compressions leaving the min. bit rate at 0, not enableing the
> > padding
> > minimium, and leaving the spoilage parameters at the default setting of 0
> > on
> > P pics and 20 on B pics. I then compressed the same mpg file using quality
> > 100, 80, and 60 against a maximum bit rate of 8000, 7000, 6000 and 5000
> > and
> > noted the resulting file size as a percentage of the original. This gave
> > me
> > some indication of the size reduction I could achieve using these
> > parameters.
> > My questions are,
> > 1) Should I reduce the quality in preference to the bit rate, or reduce
> > the
> > bit rate and leave the quality as high as possible, or reduce them both in
> > proportion to achieve the percentage size reduction I require?
> > 2) Is there a minimium value of quality or bit rate I should avoid going
> > below as it will noticably reduce the resulting video quality?
> > 3) Should I start fiddling with the other parameter settings?
> > Sorry this is so long, but I thought it best to give all the relevant
> > details of my problem
> > Thank for any help posted
>
>
>


Compression parameter settings