Vorbis - Nov 2012 - Oggenc producing a different file every time

We are using the Ogg file format in our game Awesomenauts. Now whenever I
rebuild our compressed music files from our uncompressed sources (WAV to
OGG), oggenc.exe produces different files. They sound the same, but there
are differences in the file. I did a checksum on the hex, and it turns out
there are small pieces of similar differences throughout the file.

This is a serious problem for us: whenever I run our complete build process
and produce a patch for Awesomenauts (which happens almost every week), all
audio files are different, and thus all our Steam users will have to
download 120mb of music that has not actually changed. (We also regularly
make real changes to the soundtrack in patches, so I want to keep a
complete rebuild of the soundtrack in our build process to avoid
accidentally missing things when building.)

I thought oggenc.exe might add the current date if I don't set one myself,
so I tried setting the date through "-d 1-1-2012", but that did not
help.

So, what changes every time, and how can I prevent this from happening?

Thanks in advance!

With kind regards,
Joost

-
Joost van Dongen
Lead programmer / co-founder
Ronimo Gameswww.ronimo-games.com
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On Thu, Nov 29, 2012 at 10:16 AM, Joost van Dongen
<joost at ronimo-games.com> wrote:
> We are using the Ogg file format in our game Awesomenauts. Now whenever I
> rebuild our compressed music files from our uncompressed sources (WAV to
> OGG), oggenc.exe produces different files. They sound the same, but there
> are differences in the file. I did a checksum on the hex, and it turns out
> there are small pieces of similar differences throughout the file.
Every ogg logical stream has a serial number. This serial number is
selected at random so you can usually create chained files through
straight concatenation.

For oggenc,

       -s, --serial
              Forces a specific serial number in the output stream.
This is primarily useful for testing.

I gave it a try, and that indeed fixes the problem! :) Since you mention
this is "primarily useful for testing", is there any downside to
turning
this on, or can I freely do so without worrying it will break something
else?


-
Joost van Dongen
Lead programmer / co-founder
Ronimo Gameswww.ronimo-games.com




On 29 November 2012 16:24, Gregory Maxwell <gmaxwell at gmail.com> wrote:
> On Thu, Nov 29, 2012 at 10:16 AM, Joost van Dongen
> <joost at ronimo-games.com> wrote:
> > We are using the Ogg file format in our game Awesomenauts. Now
whenever I
> > rebuild our compressed music files from our uncompressed sources (WAV
to
> > OGG), oggenc.exe produces different files. They sound the same, but
there
> > are differences in the file. I did a checksum on the hex, and it turns
> out
> > there are small pieces of similar differences throughout the file.
>
> Every ogg logical stream has a serial number. This serial number is
> selected at random so you can usually create chained files through
> straight concatenation.
>
> For oggenc,
>
>        -s, --serial
>               Forces a specific serial number in the output stream.
> This is primarily useful for testing.
>
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