Hello,
In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
-1 to 1 is the maximum range for floating point audio samples. there's nothing else you can do than clipping if you exceed that range.
Gesendet: Donnerstag, 19. Oktober 2017 um 15:23 Uhr Von: "Nicolas Danet" nicolas.danet@free.fr An: pd-list@lists.iem.at Betreff: [PD] Is Pd clip the audio output?
Hello,
In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
On 19/10/17 15:56, Christof Ressi wrote:
-1 to 1 is the maximum range for floating point audio samples. there's nothing else you can do than clipping if you exceed that range.
A simple test on Linux with JACK shows that Pd doesn't clip audio that exceeds -1 to 1:
https://mathr.co.uk/tmp/jack-no-clip.png screenshot
Other API may be different, and the driver may clip (or do other dynamics processing) before sending to the hardware.
Von: "Nicolas Danet" nicolas.danet@free.fr In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
I tested with a less current version:
$ pd -version Pd-0.47.1 ("") compiled for Debian (0.47.1-3) on 2016/11/28 at 20:56:10 UTC
Claude
Ok, thus if it there's a clipping it is "after" Pd (or at the I/O API level). Thanks for the confirmation.
----- Mail d'origine ----- De: Claude Heiland-Allen claude@mathr.co.uk À: pd-list@lists.iem.at Envoyé: Thu, 19 Oct 2017 17:10:12 +0200 (CEST) Objet: Re: [PD] Is Pd clip the audio output?
On 19/10/17 15:56, Christof Ressi wrote:
-1 to 1 is the maximum range for floating point audio samples. there's nothing else you can do than clipping if you exceed that range.
A simple test on Linux with JACK shows that Pd doesn't clip audio that exceeds -1 to 1:
https://mathr.co.uk/tmp/jack-no-clip.png screenshot
Other API may be different, and the driver may clip (or do other dynamics processing) before sending to the hardware.
Von: "Nicolas Danet" nicolas.danet@free.fr In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
I tested with a less current version:
$ pd -version Pd-0.47.1 ("") compiled for Debian (0.47.1-3) on 2016/11/28 at 20:56:10 UTC
Claude
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
The OS seems to be doing the clipping. Windows and OSX don't seem to clip while linux, at least with alsa, does.
J
On 10/19/2017 11:21 AM, Nicolas Danet wrote:
Ok, thus if it there's a clipping it is "after" Pd (or at the I/O API level). Thanks for the confirmation.
----- Mail d'origine ----- De: Claude Heiland-Allen claude@mathr.co.uk À: pd-list@lists.iem.at Envoyé: Thu, 19 Oct 2017 17:10:12 +0200 (CEST) Objet: Re: [PD] Is Pd clip the audio output?
On 19/10/17 15:56, Christof Ressi wrote:
-1 to 1 is the maximum range for floating point audio samples. there's nothing else you can do than clipping if you exceed that range.
A simple test on Linux with JACK shows that Pd doesn't clip audio that exceeds -1 to 1:
https://mathr.co.uk/tmp/jack-no-clip.png screenshot
Other API may be different, and the driver may clip (or do other dynamics processing) before sending to the hardware.
Von: "Nicolas Danet" nicolas.danet@free.fr In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
I tested with a less current version:
$ pd -version Pd-0.47.1 ("") compiled for Debian (0.47.1-3) on 2016/11/28 at 20:56:10 UTC
Claude
On Don, 2017-10-19 at 12:43 -0400, Jaime Oliver La Rosa wrote:
The OS seems to be doing the clipping. Windows and OSX don't seem to clip while linux, at least with alsa, does.
As someone else pointed out, it's not the OS, but rather the audio backend is responsible for this. It's just the nature of an DAC that it has a limited amplitude range. ALSA doesn't fuzz with your signal - fortunately! - and thus it simply clips the audio if it exceeds the limits (I know that not from reading the code, but from experience). Jack doesn't clip anything. If you send a signal from Pd to Pd over Jack, you can use the full range of 32-bit float. However, when you send the signal through Jack (and ALSA as backend of Jack) to a soundcard, then clipping occurs.
I never really figured out what goes on with Coreaudio on macOS. It seems there are multiple stages of processing (dynamic compression / dynamic limiting) involved and the processing seems even dependent on whether you use the built-in speakers or the headphone jack. If you intend to do something more scientific, you're doomed. It's news to me that similar processing goes on on Windows. Maybe that's something new with Windows 10?
Roman
On 10/19/2017 11:21 AM, Nicolas Danet wrote:
Ok, thus if it there's a clipping it is "after" Pd (or at the I/O API level). Thanks for the confirmation.
----- Mail d'origine ----- De: Claude Heiland-Allen claude@mathr.co.uk À: pd-list@lists.iem.at Envoyé: Thu, 19 Oct 2017 17:10:12 +0200 (CEST) Objet: Re: [PD] Is Pd clip the audio output?
On 19/10/17 15:56, Christof Ressi wrote:
-1 to 1 is the maximum range for floating point audio samples. there's nothing else you can do than clipping if you exceed that range.
A simple test on Linux with JACK shows that Pd doesn't clip audio that exceeds -1 to 1:
https://mathr.co.uk/tmp/jack-no-clip.png screenshot
Other API may be different, and the driver may clip (or do other dynamics processing) before sending to the hardware.
Von: "Nicolas Danet" nicolas.danet@free.fr In the "A02.amplitude.pd" example it is claimed that:
"Amplitudes of audio signals can have any reasonable range, but when you output a signal via the dac~ object, the samples should range between -1 and +1. Values out of that range will be clipped."
Is that still true in current version (Pd-0.48-0)?
I tested with a less current version:
$ pd -version Pd-0.47.1 ("") compiled for Debian (0.47.1-3) on 2016/11/28 at 20:56:10 UTC
Claude
Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/lis tinfo/pd-list
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Christof Ressi -
Claude Heiland-Allen -
Jaime Oliver La Rosa -
Nicolas Danet -
Roman Haefeli