[MEncoder-users] Fwd: Questions on Mencoder performace

[Corey Hickey]

larrystotler at netscape.net wrote:
> -----Original Message-----
> From: RC <rcooley at spamcop.net>
> 
>> No "turbo" ?  That should really speed-up the first pass, without
>> noticable quality drop.
> 
> I tried the turbo option when I started a file a little while ago.  It 
> was averaging about 13-14 at first.  It's 66% done at the moment and 
> it's at 16fps.  owever, that won't help the 2nd pass, which is why I 
> was looking for guidance.  I can get a newer MB and some DDR and 
> overclock this 2.4 to 3.2(already tested stable on a friend's machine) 
> but don't want to speed the money if there won't be that much of a 
> difference. If I could get around 25-30, then it would be wortth it.  
> But getting less than 20 isn't.

This thread is a bit confusing because there are two somewhat-separate
performance topics we're talking about: encoding and decoding.

For encoding, if you want higher performance then try using lavc instead
of xvid. Here's the rough breakdown:

- with default options, lavc is much faster but doesn't look as good as xvid
- if you use high-speed options with xvid you can make it almost as fast
as lavc but it looks much worse
- if you use high-quality options with both, then lavc can look as good
or better than xvid but the encoding is much slower

Whichever works best for you depends on what you need.

Also, xvid is only an MPEG-4 codec; lavc supports many others (see below).

>>>   I prefer XviD since it seems to work better on slow cpus(my kids
>>>   have
>>> 300-400Mhz laptops, and Xvid doesn't drop frames that bad but X264 
> did
> 
>> Xvid is the "proper" name of an MPEG-4 codec.  So is lavc (FMP4), Divx,
>> etc.  They should all have approximately the same properties, and any 
> of
>> them can playback videos created with another.
> 
>> H.264, on the other hand, is a completely different codec than regular
>> MPEG-4.  Newer, higher quality, and much more CPU-intensive.
> 
> My friend with the Xeon seems to thing that H.264 is better, but I've 
> seen problems on my slower machines.  I sometimes get a message on my 
> Dual Xeon 500 that "Your machine is too slow to play this", but never 
> see any frame drops.  There have been many debates that I have read 
> about how one is better than the other.  I just want to standardize on 
> 1 and not worry about it after that.

H.264 is indeed higher quality, but yes, for decoding, it's quite a bit
slower than MPEG-4. If MPEG-4 is still too slow for you, then try MPEG-2
or MPEG-1. Decoding is faster, but, of course, the encoding isn't as
efficient and they won't look quite as good.

If you use MPEG-2 or MPEG-1, then the lavc vs. xvid choice is
unnecessary since xvid is MPEG-4-only.

-Corey