Audio visualization does not seem to render correctly 8-bit wave forms

[esaule]

I generated a simple clip using freqPlayer in 8-bit. The sound that plays seems correct, but the wave form visualization seems broken.

http://bridges-cs.herokuapp.com/assignments/4583/esaule

I don't know enough webGL and JS to debug the issue. Maybe @krs-world , @quaiquai , or @AlecGoncharow knows how to debug it?

[esaule]

Here is an encoding of the same clip but in 16 bits http://bridges-cs.herokuapp.com/assignments/4584/esaule
They sound about the same (despite the 8-bit one is definitely a 8 bit sound). But the wave form is quite different. The 16-bit waveform is consistent with exceptation, while the 8-bit one is not.

[krs-world]

Assume you are using Java version? Yeah, I dont see the wave visualization at all. I am still fighting with the C++ version.. the conversion of the audio data to little-endian combined with the sign of teh values is causing incorrect values for the audio data.. — krs

…

_________________________________________________________________________________ K.R.Subramanian Phone: (704) 687-8579 Assoc. Professor, Computer Science FAX: (704) 687-3516 UNC Charlotte, Woodward 435E Email: krs@uncc.edu Charlotte, NC 28223-0001 www.cs.uncc.edu/~krs ----------------------------------------------------------- If you are not the intended recipient of this transmission or a person responsible for delivering it to the intended recipient, any disclosure, copying, distribution, or other use of any of the information in this transmission is strictly prohibited. If you have received this transmission in error, please notify me immediately. Thank you.

On Jul 15, 2020, at 12:14 PM, Erik Saule ***@***.***> wrote: I generated a simple clip using freqPlayer in 8-bit. The sound that plays seems correct, but the wave form visualization seems broken. http://bridges-cs.herokuapp.com/assignments/4583/esaule <http://bridges-cs.herokuapp.com/assignments/4583/esaule> I don't know enough webGL and JS to debug the issue. Maybe @krs-world <https://github.com/krs-world> , @quaiquai <https://github.com/quaiquai> , or @AlecGoncharow <https://github.com/AlecGoncharow> knows how to debug it? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#56>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABLFEOESF4M5M2OWQDVCT2DR3XIXDANCNFSM4O2VOISA>.

[esaule]

I am using the C++ API actually. I am synthesizing the wave form from sine functions, so I don't need the reader. I pushed tiny changes to AudioClip BTW to throw exception when values are out of bound.

[esaule]

I just fixed the issue. It is fixed in master, not propagated to heroku yet.

It was a webclient problem.
The audio.js code reconstruct a wav file from the data in bridges. Bridges represent all PCM data signed, but Wav specifies 8-bit as unsigned. So there was a need to convert in webclient javascript.