Hi All,
As specified in earlier email we have released the trial version of the ogg
vorbis decoder. Along with the decoder we have released an experimental version
of the bitrate peeler that we have used to test the decoder for bitrate peeled
inputs. We have made the executable of the bitrate peeler available from our
website downloads section.
www.vinjey.com/ogg_downloads.html
We need inputs with respect to results of this bitrate peeler. This bitrate
peeler reduces the bitrate by cutting the packets based on the factor input
provided by the user. Source code of this experimental bitrate peeler comes
along with our free trial version of the decoder.
Regards,
Vinoth
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> ??? ?We need inputs with respect to results of this bitrate peeler. > This bitrate peeler reduces the bitrate by cutting the packets based > on the factor input provided by the user.You mean, you peel every packet by throwing away the same ratio of bits (or bytes, really)? And with an unmodified encoder? Forget it, that is the second worst scheme possible (the worst is throwing away all packet contents completely). Been there done that. To do good peeling, you really need access to the masking curves, and there is no way to reconstruct that (cheaply) from the info in current Vorbis streams. Well there is part of that info in the floor curves, but the transform used (windowed DCT-IV) plays nasty aliasing games, most easily heard in the upper frequencies (but not even the worst there -- adaptive low-pass algorithms can hide most of this).> Source code of this experimental bitrate peeler comes along with our > free trial version of the decoder.I couldn't find it... didn't look too hard, though. Good luck, I really do hope you _do_ find a magic bullet, Segher
Hi Seghar, John,
Seghar and John - Thanks for your inputs.
We have implemented this bitrate peeler primarily to test the new decoder
developed by us. To put it in other words, bpeel is one of the 14 tools we
developed and tested the decoder. So we didn't have really much of chance to
check the bpeel as a tool and hence bpeel was released without much or no
internal testing.
Now with inputs from different people on mailing lists, forums and emails we
have found how much importance people give for a bitrate peeler without any
noise ;-). This has kindled interest among our engineers to start working on
bitrate peeler. Once we have some updates on our work on bitrate peeler we will
post back the results.
Regards,
Vinoth
On Tue, 24 May 2005 Segher Boessenkool wrote :> > ??? ?We need inputs with respect to results of this
> bitrate peeler.
> > This bitrate peeler reduces the bitrate by cutting
> the packets based
> > on the factor input provided by the user.
>
> You mean, you peel every packet by throwing away the
> same ratio of
> bits (or bytes, really)? And with an unmodified
> encoder? Forget
> it, that is the second worst scheme possible (the worst
> is throwing
> away all packet contents completely). Been there done
> that.
>
> To do good peeling, you really need access to the
> masking curves,
> and there is no way to reconstruct that (cheaply) from
> the info
> in current Vorbis streams. Well there is part of that
> info in
> the floor curves, but the transform used (windowed
> DCT-IV) plays
> nasty aliasing games, most easily heard in the upper
> frequencies
> (but not even the worst there -- adaptive low-pass
> algorithms
> can hide most of this).
>
> > Source code of this experimental bitrate peeler
> comes along with our
> > free trial version of the decoder.
>
> I couldn't find it... didn't look too hard, though.
>
> Good luck, I really do hope you _do_ find a magic
> bullet,
>
>
> Segher
>