XviD: Qpel, GMC, Max consecutive B-VOPs, and N-VOP ??

[GangstaRap]

Can someone pleeease explain me those expressions?
Qpel
GMC
B-VOP (Max consecutive B-VOPs)
N-VOP

Thanks!

[jagabo]

http://www.gromkov.com/faq/conversion/xvid_options.html
http://forum.doom9.org/showthread.php?s=&threadid=16935

[jman98]

QPel and GMC should be avoided for best compatibility with standalone DVD players, should you care about that. Technically you can use GMC, but you have to keep the warp point at 1. Xvid defaults to 3 and that's a problem on most standalone DVD players that support Divx.

[GangstaRap]

jagabo,
thanks for the links! they're great!

jman98,
thanks for the tip too!

[celtic_druid]

Actually Xvid uses whatever warp points it can, excluding 1 warp point since it is basically useless. If it only finds one reference it just ignores and encode a P-VOP. So you will get 2/3 warp points.

If you encode using a Home Theatre profile, then Xvid will disable Qpel, GMC, limit B-VOP's to 1 consecutive and in my builds force no N-VOP's (ESS based players don't like them). With regular Xvid builds, if two frames are 100% identical, it will drop one and insert an N-VOP.

[GangstaRap]

thanks for your reply man!

force no N-VOP's (ESS based players don't like them). With regular Xvid builds, if two frames are 100% identical, it will drop one and insert an N-VOP.

now i'm confused...
what if i want ESS and MediaTek compatible?
should i disable\enable N-VOP's?


Thanks In Advance!

[jagabo]

what if i want ESS and MediaTek compatible?
should i disable\enable N-VOP's?

Go for the lowest common denominator. Disable N-VOPs.

[GangstaRap]

jagabo, thanks for that man!

[GangstaRap]

OK i've got another question,
its about the link you gave me:
http://www.gromkov.com/faq/conversion/xvid_options.html
its really great and it helped me a lot.
in this Explanation the author recommend to define "AS@Level5(Profile), nothing else".
why is it really matter to pick AS@Level5 over Unrestricted if i'm gonna leave the default xvid preferences anyway?

thanks in advance!

[jagabo]

The profile levels force some limitations on the encoder. For example, some set-top players have trouble with bitrates over 3000 kbps. Using AS@level4 will limit the bitrate to a max of 3000 kbps in a 2-pass encode. Unrestricted might end up using more than 3000 kbps in some scenes.

[jman98]

The profile levels force some limitations on the encoder. For example, some set-top players have trouble with bitrates over 3000 kbps. Using AS@level4 will limit the bitrate to a max of 3000 kbps in a 2-pass encode. Unrestricted might end up using more than 3000 kbps in some scenes.

Not only is this true, on some standalone DVD players that support Divx, if the video bit rate is above 2000 Kbps, the player may not be able to play any audio correctly except for MP3. If you want to use Dolby AC3 or DTS audio with a Divx/Xvid encode, you probably should keep your video bit rate below 2000 for best results. You may need to stay below 1500 if you use DTS, but that's a just a general guideline. It's best to test with specific players as some may have more recent decoding chips that can tolerate higher bit rates.

[GangstaRap]

first of all thanks for your support! you're the best!

so is it precise to say that the lowest the profile(AS@level X) level will be - the more compatible in DVD players it'll be?

thanks!

[celtic_druid]

Yeah, ESS is the lowest you can get (well excluding SunPlus). For hardware compatiblity you should stick with the Home Theater profiles.

[GangstaRap]

celtic_druid, thanks for your post man!

so, Home Theater will get me maximum compatibility?
ESS players cant handle AS@levelX?

Thanks!

[celtic_druid]

ASP means GMC and qpel. So I don't think any players can handle ASP@L?. Sure you can turn them off, but the HT profiles use VBV values based on DivX's HT profile. If you just look at the max bitrate for example L5 is too high and L4 is too low. Some players can handle higher bitrates/spikes which is why I added extra MTK profiles. Really though players should have been designed around ASP@L5 I guess though.

[GangstaRap]

celtic_druid, thanks again man! appreciate it!
so your advice is HT and to disable GMC and qpel for best compatibility?
anything else i should consider?

Thanks in advance!

[celtic_druid]

My advice is HT which doesn't let you enable GMC or qpel. No need to disable them.

[GangstaRap]

celtic_druid, OK Thanks for the great help man!