[opus] Encoding ultrasonics

Benjamin Schwartz benjamin.m.schwartz at gmail.com
Wed Jan 16 20:28:30 PST 2013


Opus shouldn't be particularly worse than Vorbis for this application ...
but it also probably won't be any better, and it will take more CPU power
to decode.  Vorbis is still a fine choice.

If you are CPU-constrained, you might consider encoding more than one
version of the audio at different base speeds, so that when playing at full
speed or faster, you don't have to burn twice the CPU on decoding.


On Wed, Jan 16, 2013 at 11:55 AM, Corey Shay <cshay892 at gmail.com> wrote:

> Well, Vorbis doesn't sound too terrible when pitched down, though,
> admittedly we haven't tried it with rates over 48k. It sounds close enough
> to the original when pitched down to pass just fine.
>
>
> On Wed, Jan 16, 2013 at 11:50 AM, Gregory Maxwell <gmaxwell at gmail.com>wrote:
>
>> On Wed, Jan 16, 2013 at 2:45 PM, Corey Shay <cshay892 at gmail.com> wrote:
>> > Why use Opus for this? Video games, of course. Memory
>> > constraints.
>>
>> If you use Opus or any other lossy encoder for this you will violate
>> their perceptual assumptions and get results that sound like crud. A
>> lossy codec (or encoder) could— in theory— be design to work more
>> sanely in this use case, but not for the Opus format (because much of
>> the encoder's behavior is baked into the format for efficiency
>> reasons) and not without substantially compromising the effectiveness
>> of the lossy compression.
>>
>
>
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