What's the DC precision? only, especially, question, setting

andy

What's the quot;DC precisionquot;? Does it affect quality?
(Newbie)

You don't need know what it is
If you encode stream for DVD-Video you can use 8,9 or 10 bit. The prefered setting is 10 (use this setting), especially when footege is hard to encode. It has some affect for quality but not big. Look to CCE manual.

You don't need know what it is

No a good answer. I can't realy help you to answer your question, too. But I think it has effect on the color of the video.

The only thing I can say. If you have an average Bitrate over 2000Kbps and a max bitrate till 6000Kpbs you should use 9 as value. Average Bitrates under 2000Kbps you should choose 8. If you have a higher average Bitrate and a max bitrate set over 6000Kbps like 7500 or 9800 then use 10. This gives you the best quality.

well i thought i would try using google just to see how hard it is to find such information. amazingly not hard at all.

to answer your question though

from here frank/mpegfaq/mpe1736.html
quot;intra_dc_precision: the MPEG-1 DC value is mandatory quantized to a
precision of 8 bits.  MPEG-2 introduced 9, 10, and 11 bit precision set
on a picture basis to increase the accuracy of the DC component, which
by very nature, has the most significant contribution towards picture
quality.  Particularly useful at high bit rates to reduce
posterization. Main and Simple Profiles are limited to 8, 9, or 10 bits
of precision.quot;

and here mpeg/mpcs/faqe.html
quot;In MPEG-2 video, Intra DC Precision indicates the number of bits for quantized DC coefficients of intra-coded blocks; it takes one of the values of 8, 9, 10, or 11 bits. The more bits are used, the more precise quantization is achieved.quot;

anyway Encoder Master basically has it right. higher DC precision is better quality but does require more space so better for higher bitrates. so useing a lower precision for lower bitrates is reccomended.

That's true.
I never use bitrate less then 5Mbit, but I always use 10bit.

Thanks dragongodz.

Ye, thanks

question:  why is mpeg-4 ASP limited to 8 bit DC?

i've heard somewhere that qpel is meant to reduce posterization, but it clearly does not if you actually feed the encoder smooth moving gradients - even at quant 2.

i've heard somewhere that qpel is meant to reduce posterization

for some info on QPEL go here
docs/xvidfaq.html
and read quot;C3e. How does Q-Pel work and when should I use it?quot;.

Originally posted by Mug Funky
question:  why is mpeg-4 ASP limited to 8 bit DC?Because its ASP
There are higher profiles / levels (Studio) that allow higher DC precision in MPEG4. AFAIK Sony's HDCAM uses it (4:2:2 and 4:4:4 sampling with higher DC precision and lots more).