[vorbis] Different average bitrates on different machines

[John Denton]

Hi,

I apologise in advance for the length of this message. My other groups
(Windows users!) get paranoic about attachments, so I've copied the results
of my initial tests below. This accidental discovery is important to me.

The difference appears to be the physical location of  source/destination
and the operating system. With Win2K *only* if these are all on the same
physical drive I'm getting twice the encoding speed.

Subsequently I encoded the largest wav straight from the command prompt in
Win2K to find out if communication between my wrapper and OggEnc were OK -
the results are at the bottom below and are identical to those produced
through my wrapper (same drives).

I have only tested the CVS version of OggEnc.

Note that the pipes between my wrapper and OggEnc sometimes miss the summary
at the end of encoding. This seems better in Win2K - needs a rewrite :-)
Throughout, the wrapper program is on Drive E: (first drive) with OggEnc in
the same folder. OggEnc is fired separately for each track of the batch to
be encoded..

I think I can hone this some more :-)

// -------------------------------------------------------------

Win98 - Drive C: (first hard drive):
Wavs from Drive L: (second hard drive):
Encoding to N: (second hard drive)

Done encoding file 1
 File length:  4m 28.0s
 Elapsed time: 2m 13.0s
 Rate:         2.0193
 Average bitrate: 125.1 kb/s

Done encoding file 2
 File length:  3m 56.0s
 Elapsed time: 1m 56.0s
 Rate:         2.0414
 Average bitrate: 125.9 kb/s

Done encoding file 3
 File length:  3m 59.0s
 Elapsed time: 1m 59.0s
 Rate:         2.0149
 Average bitrate: 127.6 kb/

Done encoding file 4
 File length:  3m 23.0s
 Elapsed time: 1m 41.0s
 Rate:         2.0182
 Average bitrate: 123.2 kb/s

Encoding: 5
Done.

Done encoding file 6
 File length:  4m 03.0s
 Elapsed time: 2m 00.0s
 Rate:         2.0313
 Average bitrate: 131.7 kb/s
Done.

// -----------------------------------------------------------

Win98 - Drive C: (first hard drive):
Wavs from Drive E: (first hard drive):
Encoding to N: (second hard drive)

Encoding: 1
Done.

Done encoding file 2
 File length:  3m 56.0s
 Elapsed time: 1m 56.0s
 Rate:         2.0414
 Average bitrate: 125.9 kb/s
Done.

Encoding: 3
Done.

Done encoding file 4
 File length:  3m 23.0s
 Elapsed time: 1m 39.0s
 Rate:         2.0590
 Average bitrate: 123.2 kb/s
Done.

Done encoding file 5
 File length:  3m 37.0s
 Elapsed time: 1m 48.0s
 Rate:         2.0113
 Average bitrate: 122.0 kb/s
Done.

Encoding: 6
Done.

// -----------------------------------------------------------

Win2000Pro - Drive D: (second hard drive):
Wavs from Drive L: (second hard drive):
Encoding to N: (second hard drive)

Done encoding file 1
 File length:  4m 28.0s
 Elapsed time: 0m 57.0s
 Rate:         4.7118
 Average bitrate: 125.1 kb/s
Done.

Done encoding file 2
 File length:  3m 56.0s
 Elapsed time: 0m 50.0s
 Rate:         4.7359
 Average bitrate: 125.9 kb/s
Done.

Done encoding file 3
 File length:  3m 59.0s
 Elapsed time: 0m 51.0s
 Rate:         4.7014
 Average bitrate: 127.6 kb/s
Done.

Done encoding file 4
 File length:  3m 23.0s
 Elapsed time: 0m 43.0s
 Rate:         4.7404
 Average bitrate: 123.2 kb/s
Done.

Done encoding file 5
 File length:  3m 37.0s
 Elapsed time: 0m 45.0s
 Rate:         4.8272
 Average bitrate: 122.0 kb/s
Done.

Done encoding file 6
 File length:  4m 03.0s
 Elapsed time: 0m 52.0s
 Rate:         4.6877
 Average bitrate: 131.7 kb/s
Done.

// -----------------------------------------------------------

Win2000Pro - Drive D: (second hard drive):
Wavs from Drive E: (first hard drive):
Encoding to N: (second hard drive)

Encoding: 1
Done.

Done encoding file 2
 File length:  3m 56.0s
 Elapsed time: 1m 56.0s
 Rate:         2.0414
 Average bitrate: 125.9 kb/s
Done.

Done encoding file 3
Done.

Done encoding file 4
 File length:  3m 23.0s
 Elapsed time: 1m 39.0s
 Rate:         2.0590
 Average bitrate: 123.2 kb/s
Done.

Done encoding file 5
 File length:  3m 37.0s
 Elapsed time: 1m 48.0s
 Rate:         2.0113
 Average bitrate: 122.0 kb/s
Done.

Encoding: 6
Done.

// -----------------------------------------------------------

OggEnc (compiled from recent CVS) run from Command prompt (manually compiled
here):
Win2000Pro - Drive D: (second hard drive):
Wavs from Drive D\Temp: (second hard drive):
Encoding to D\Temp: (second hard drive)

Done encoding file 1 - "D:\Temp\1.ogg"
 File length:  4m 28.0s
 Elapsed time: 0m 57.0s
 Rate:         4.7118
 Average bitrate: 125.1 kb/s
Done.

<p><p><p>J.

<p>----- Original Message -----
From: "Jack Moffitt" <jack at xiph.org>
To: <vorbis at xiph.org>
Sent: Monday, December 10, 2001 9:18 PM
Subject: Re: [vorbis] Different average bitrates on different machines

<p>> > > I bet it's a dual CPU.
> >
> > The vorbis libraries are not multithreaded, so I don't think this is the
case.
>
> Even so, the speedup would be a few percent, not 100%.  Doubling the
> speed of an app even by adding a cpu and making the libs multithreaded
> would still yield less than 100%.
>
> jack.
>
> --- >8 ----
> List archives:  http://www.xiph.org/archives/
> Ogg project homepage: http://www.xiph.org/ogg/
> To unsubscribe from this list, send a message to 'vorbis-request at xiph.org'
> containing only the word 'unsubscribe' in the body.  No subject is needed.
> Unsubscribe messages sent to the list will be ignored/filtered.
>
>
>

<p>--- >8 ----
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