G
Guest
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
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
