intra-dc precision?

[mistycat]

Using Mainconcept to convert files to DVD, is there any benefit to quality by raising intra-dc precision to 10 or is 8,9 better? I thought I read recently that 8 was better in Mainconcept while 10 was best in TMPGEnc but I can't remember where. Thanks

[SaSi]

Typically, this value doesn't have to do with each encoder individually but with the encoded video characteristics and selected bitrate.

At higher bitrates (>6Mbps) it's much better to use 10bits precision. At low bitrates, higher DC precision defeats the purpose and will probably give worse results.

I personally use 10 bits for AVG 6Mbps and above, 9 for 3500~4500 and 8 bits for low bitrate encoding (e.g. 1.5Mbps for quarter size frame).

[SatStorm]

Exactly.
I use only 8bit on both encoders, because when I encode to 1/2 D1 (352 x 576) I never go higher 4000.
When you use 9 or 10 bit with lower (<5000) bitrates, you end up with a more smooth picture and more macroblocks. Only CCE is an exception on thing (there you have something called "mosquito" noise, which some people find it better than macroblocking)

[SaSi]

CCE tends to generate noise before encoding, which creates what looks like a film effect. In general, CCE will smoothen the picture before encoding in low bitrates avoiding the macroblock visibility.

I believe that the best benchmark video for testing the DC precision values is one with a close-up on a human face or a very dark scene.

A low DC precision value will create very visible boundary effect. If you need, say, 20 different shades of grey-to-black to encode the dark scene, a low DC value may give you only 4 while a larger may give you 15 or so.

Higher DC precision takes up more bits and requires a higher bitrate.

[mistycat]

Thanks for the replies.

[mistycat]

Actually, while I'm here, one more question please. In Motion search pixel movement, would there be any quality increase seen in a file over 5500 bitrate by going above values of 7? Thanks again

[SaSi]

There are two sliders there. One is for motion search range and the second for motion search mode.

Setting search range to more than 16 is outright useless. A value between 8 and 10 should be considered a realistic max.

In motion search mode, the higher the value the slower the encoding and the better the result.

However, values above 20 seem to only deteriorate performance. I use 16 there (actually set both sliders to the middle - almost).

Practically, the defaults of the encoder seem to offer the best balance between speed and quality.