Vorbis - Apr 2002 - encoding bitrates, different machines...

I found I have ripped the same CD twice with different machines. Cannot 
remember when, why, or how, but anyway. I've been using jack, here is 
relevant output:

first one:

01/|\enc/|\128/|\[coding @0.67× done,129kbit]
02/|\enc/|\128/|\[coding @0.69× done,124kbit]
03/|\enc/|\128/|\[coding @0.66× done,124kbit]
<etc>

econd one:

01/|\enc/|\128/|\[coding @5.50× done,116kbit]
02/|\enc/|\128/|\[coding @2.24× done,120kbit]
03/|\enc/|\128/|\[coding @1.40× done,121kbit]
<etc>

Note the big difference in bit rate... both is RC3. My best guess at the 
moment is that the former was with a -b setting while the latter was 
with a -q setting. I usually do everything at -q, but it might be that I 
forgot to do so with the former.

It won't be different CPU's (P2 vs. AMD Athlon), would it? There's
no
CPU specific optimisations yet, e.g. selecting 3dnow instructions for 
the latter.

Does 129 and 124kbit look about right for a -b setting, does one get
that kind of range? Here I'm missing that "encoding parameters"
tag.
Hehe.

Both have:

bitrate_upper=none
bitrate_nominal=128031
bitrate_lower=none

Thanks,
Hugo

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My guess is your bitrate varience has nothing to do with vorbis, its
probably in the ripping, files can vary greatly depending on how you rip
them, if its a crappier rip you'll most likely see higher bit rates.

Later,
Alan
> -----Original Message-----
> From: owner-vorbis@xiph.org [mailto:owner-vorbis@xiph.org]On Behalf Of
> Hugo van der Merwe
> Sent: Thursday, April 11, 2002 3:14 AM
> To: vorbis mailing list
> Subject: [vorbis] encoding bitrates, different machines...
>
>
> I found I have ripped the same CD twice with different machines. Cannot
> remember when, why, or how, but anyway. I've been using jack, here is
> relevant output:
>
> first one:
>
> 01/|\enc/|\128/|\[coding @0.67× done,129kbit]
> 02/|\enc/|\128/|\[coding @0.69× done,124kbit]
> 03/|\enc/|\128/|\[coding @0.66× done,124kbit]
> <etc>
>
> second one:
>
> 01/|\enc/|\128/|\[coding @5.50× done,116kbit]
> 02/|\enc/|\128/|\[coding @2.24× done,120kbit]
> 03/|\enc/|\128/|\[coding @1.40× done,121kbit]
> <etc>
>
> Note the big difference in bit rate... both is RC3. My best guess at the
> moment is that the former was with a -b setting while the latter was
> with a -q setting. I usually do everything at -q, but it might be that I
> forgot to do so with the former.
>
> It won't be different CPU's (P2 vs. AMD Athlon), would it?
There's no
> CPU specific optimisations yet, e.g. selecting 3dnow instructions for
> the latter.
>
> Does 129 and 124kbit look about right for a -b setting, does one get
> that kind of range? Here I'm missing that "encoding
parameters" tag.
> Hehe.
>
> Both have:
>
> bitrate_upper=none
> bitrate_nominal=128031
> bitrate_lower=none
>
> Thanks,
> Hugo
>
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> I found I have ripped the same CD twice with different machines. Cannot 
> remember when, why, or how, but anyway. I've been using jack, here is 
> relevant output: [...]
Did you compared ripped tracks to see if they where identical ?
If you rip the same track with the same CD reader several times and
you compare them you'll found they're all different each other. This
happens with almost all IDE CDs. Even my Plextor (SCSI) sometimes
misses a bit here and there, but it usually works fine.

btw, I tried to encode the same track with the same machine 4 times. The
encoded files had the same size, but cmp -l showed many different bytes.
Strange.

<p><p><p>Bye.

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Hello Hugo,

11. april 2002, 9:13:53, you wrote:
> Note the big difference in bit rate... both is RC3. My best guess at the
> moment is that the former was with a -b setting while the latter was 
> with a -q setting. I usually do everything at -q, but it might be that I 
> forgot to do so with the former.
Of course there is difference if you compressed one set of files with
-q and the others with -b. I remember seeing a bitrate graph shortly
after rc3 was released of the same track encoded with -b and -q. While
the -b graph was more or less around the average bitrate, the av.
bitrate in the last third of track encoded with -q was almost twice the
av. bitrate of the first part of track.


-- 
Jernej Simoncic, jernej.simoncic@guest.arnes.si
http://www2.arnes.si/~sopjsimo/
ICQ: 26266467

1. Everything is cold except what should be.
2. Everything, including the corn flakes, is greasy.
       -- Laws of Institutional Food

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