best motion search option to increase encoding speed while keeping quality?

[visualhippocracy]

I'm converting 2 Min. WMV files to MP4 using Xvid4PSP & wanted to know which motion search option can I use to make the encoding really fast without any reduction in quality. Currently the motion search is set Ultra High and it takes 5 to 10 mins. to encode a 2 min. video.
I want to bring down the encoding speed to at most 2 minutes per video.
Which option should I select?
My Specs are :
Core2Duo processor 1.83 GHz.
3 GB DDRII RAM
Nvidia Geforce 8400M GS
As you see I have decent specifications to convert fast. But still it takes a long time.
Please help.
Also when I play the file on my computer its fine but when I play it in my 5800 xpress the video just pauses at places while audio is running, I have to pause the video and click play to then make it run.
Can anyone tell me why this is happening. This happened after I selected the Xvid ultra HQ in the encoding section and set bitrate to 1300 kbps 1 pass(2 pass caused the video to pause every 5 seconds , but it only happened once when I selected 1 pass)
I'm downscaling videos from 1280x720 to 640x360.

[Bjs]

Not using the "ultra" setting would speed it up but then the quality may suffer ... of course it depends entirely on the input source ... if your down scaling the input on the output you can get away with a lot of things.

As for that 5800 xpress ... them problems stem from two usual places.

1: Not adhering to exact file format specifications required for such devices ... check and re-encode.
2: Device or external memory issues

Many issues with playback can be solved by first checking for updates related to the product ... apply ... reassess for symptoms using a file specifically encoded that meets the format required by that device.

[jagabo]

Using lower motion search precision in bitrate mode will reduce the quality. The question is "by how much?" That will depend on the nature of the video and the bitrate used. You probably will barely notice the difference between the highest setting and the medium settings even if you open the videos side by side and zoom in on individual frames. At the lowest settings you'll probably be able to see a difference with most video (unless you are using very high bitrates). It's up to you to decide where the difference begins to bother you.

You're playback problems are probably because bitrate peaks in VBR mode are getting too high for the phone. Lowering the peak bitrate will probably prevent the problem. Try using the Advanced Simple @L3 or L4 profiles. Or maybe the Portable or Home profiles.

[visualhippocracy]

Thanx for the replies. I found by trial and error that motion search around level 4 works fine. And quality is great too!

[jagabo]

Since it's hard to see small difference in quality the best way to get an idea of how motion search precision effect compression is to use Target Quantizer (constant quality) mode. With constant quality encoding the more motion vectors the encoder finds the smaller the resulting file is. You'll see that the differences between MSP=0 and MSP=1 is significant. As you go the higher settings the differences get smaller and smaller.

For example, with Target Quantizer encoding the difference between MSP=1 and MSP=2 might be a 15 percent smaller file. Conversely, with bitrate based encoding that means you would need a 15 percent higher bitrate encoding at MSP=1 to deliver the same quality as encoding at MSP=2. But the difference between MSP=5 and MSP=6 might only be a 0.1 percent smaller file. For most video the difference between MSP=3 and MSP=6 is rarely more than a few percent.

Normally I'd suggest you use Target Quantizer encoding. With TQ encoding you always know what the quality of your video will be and its twice as fast as 2-pass VBR encoding. But you don't know what the file size (average bitrate) will be. In your particular case your playback device appears to have severe restrictions on bitrate peaks and you can't limit peaks with TQ encoding. So it would be inappropriate to use TQ encoding.

Once again, keep in mind that every video is different. Just because a particular video isn't effected much by MSP doesn't mean all videos won't be effect much. For example, a video with no motion (like a slideshow with no transition effects) won't benefit from more MSP at all.