[asterisk-bugs] [JIRA] (ASTERISK-28511) Bad sound quality when up sampling from SLIN16 to SLIN32

[Ruddy G (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-28511?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ruddy G updated ASTERISK-28511:
-------------------------------

    Attachment: compare-outputs.png
                output.sln32
                audacity-162362.117-in.wav
                162362.117-in.sln16

162362.117-in.sln16 is an original audio file recorded in SLN16 format.

output.sln32 is the conversion of 162362.117-in.sln16 in tho SLN32 by Asterisk. (file convert 162362.117-in.sln16 output.sln32)

audacity-162362.117-in.wav is the conversion of 162362.117-in.sln16 to 32kHz using Audacity.

compare-outputs.png is the comparaison between asterisk conversion and audacity conversion

> Bad sound quality when up sampling from SLIN16 to SLIN32
> --------------------------------------------------------
>
>                 Key: ASTERISK-28511
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-28511
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Formats/format_sln
>    Affects Versions: 13.28.0
>            Reporter: Ruddy G
>         Attachments: 162362.117-in.sln16, audacity-162362.117-in.wav, compare-outputs.png, output.sln32
>
>
> When asterisk receive a SIP call in SLIN16 codec and have to convert it to SLIN32, there is a degradation of sound quality at the places where we have voice saturation.
> There is a sign inversion which creates a bad voice quality.
> The same issue is present when converting a SLIN16 to SLIN32 format from the CLI interface.
> Please see audio files in attachment as well as the screenshot.
> Such issue is not present when we upscale the same file from another tool such as Audacity.



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