opus - Jan 2025 - Opus 1.5.2 low hum in input file results overblown output at decoding

There was a post in the Opus subthread on HA where there was a link to 
the file called
Opus-tools-0.2-34-g98f3ddc_(using_libopus_1.5.2-21-gff6dea5)_Win_GCC142.7z.
That's the one I'm currently using.
First, I used GoldWave to convert your input file from ?-law to PCM and 
saved it as a ".wav" file.
Next, I encoded it with Opusenc, I decoded its result with Opusdec with 
the target sample rate being set to 48 kHz, and I got no excessive 
amplification.
Not sure what's taking place on your side.

Petr

Thanks for looking into this. I've played with the options I'm setting
on the decoder and narrowed the issue down to DTX. If DTX is enabled, I get the
reported behavior, but it does not happen with DTX disabled.

I've posted a revised example:
https://github.com/xiph/opus/issues/382

In this new version, I've removed the Microsoft-specific code and it
runs/reproduces on Linux now as well. Also, to simplify things further, I
replaced the mu-law input file with a linear16 sample file and removed the extra
code to do the conversion from mu-law to linear in the sample app.

I don't believe that the opustools utilities support controlling DTX option,
so I don't think this can be reproduced using those tools. But if you have a
built opus and a recent C++ compiler, it should be dead simple to compile and
run this sample application. I put an example command line for compiling under
Linux in the README.

My application is mostly network transmitted audio (RTP) containing speech, so
disabling DTX is very undesirable.

Kevin O'Connor

-----Original Message-----
From: opus <opus-bounces at xiph.org> On Behalf Of Petr Par?zek
Sent: Friday, January 24, 2025 12:03 PM
To: opus at xiph.org
Subject: Re: [opus] Opus 1.5.2 low hum in input file results overblown output at
decoding

?EXTERNAL EMAIL - Please use caution with links and attachments?

There was a post in the Opus subthread on HA where there was a link to the file
called
Opus-tools-0.2-34-g98f3ddc_(using_libopus_1.5.2-21-gff6dea5)_Win_GCC142.7z.
That's the one I'm currently using.
First, I used GoldWave to convert your input file from ?-law to PCM and saved it
as a ".wav" file.
Next, I encoded it with Opusenc, I decoded its result with Opusdec with the
target sample rate being set to 48 kHz, and I got no excessive amplification.
Not sure what's taking place on your side.

Petr




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