java - Representing music audio samples in terms of dB? -


this question has answer here:

i starting project allow me use java read sound samples, , depending on properties of each sample (i'm thinking focusing on decibels @ moment sake of simplification, or finding way compute overall 'volume' of specific sample or set of samples), return value 0-255 0 silence , 255 highest sound pressure (compared reference point, suppose? have no idea how word this). want have these values returned bytes , sent arduino in order control intensity of led's using pwm, , visually 'see' music.

i not sort of audio file format expert, , have no particular understanding of how data stored in music file. such, having trouble finding out how read sample , find way represent overall volume level byte. have looked through javax.sound.sampled package , confusing me. insight how accomplish appreciated.

as bastyen (+1 me) indicates, calculating decibels not simple, requires looking @ large number of samples. however, since sound samples run more visual frames in animation, making aggregate measure works out rather neatly.

a nice visual animation rate, example, updates 60 times per second, , common sampling rate sound 44100 times per second. so, 735 samples (44100 / 60 = 735) might end being choice interfacing visualizer.

by way, of official java tutorials i've read (i big fan), have found ones accompany javax.sound.sampled difficult. http://docs.oracle.com/javase/tutorial/sound/toc.html
still worth reading. if in charge of rewrite, there many more code examples. of best code examples in several sections deep, e.g., "using files , format converters" discussion.

if don't wish compute rms, hack store local high and/or low value given number of samples. relating these numbers decibels dubious, maybe useful after giving mapping of choice visualizer. part of problem values single point on given wave can range wildly. local high might more due phase of constituent harmonics happening line energy or volume.

your pcm top , bottom values not 0 , 256, more -128 127 8-bit encoding. more common still 16-bit encoding (-32768 32767). hang of if follow bastyen's links. make code independent of bit-encoding, normalize data (convert floats between -1 , 1) before doing other calculations.


Comments

Post a Comment

Popular posts from this blog

jquery - How can I dynamically add a browser tab? -

since using iframes house external pages are, accounts "not preferred method" , disallowed sites (flickr, one), want dynamically generate browser tabs. e.g., when user submits form, want dynamically generate tab on browser in response submitted. e.g., might want add new tab url like: http://www.bigsurgarrapata.com/contact how in jquery? you want form target attribute action attribute. http://www.w3schools.com/tags/att_form_target.asp browsers have ultimate control on result of target attribute open new tab value of _blank. <form action="contact_submit.php" target="_blank" method="post">
Read more

node.js - Getting the socket id,user id pair of a logged in user(s) -

i have web application done using node js , in it,i have authentication system requires users log in before can access pages. have 2 pages,the homepage , updates page. from read docs,a new socket id issued when user opens tab in browser. me being admin,i know socket id of logged in user , more so,the socket id,logged in user id pair logged in users. what method can use socket id,logged in user id pair make sure broadcast realtime info users online?.
Read more

keyboard - C++ GetAsyncKeyState alternative -

i using windows.h library's getasynckeystate function define key pushed on keyboard . here program returns int value of pushed key example. #include <iostream> #include <windows.h> using namespace std; int main (){ char i; for(i=8;i<190;i++){ if(getasynckeystate(i)== -32767){ cout<<int (i)<<endl; } } return 0; } but trying make opengl simple game , function appeared slow . there function not need cycle 180 times , if statement . thanks you're trying make opengl game, you're going use glfw. if that's case can away using glfwgetkey() such: if (glfwgetkey(glfw_key_up) == glfw_press) {...} if (glfwgetkey(glfw_key_down) == glfw_press) {...} that method nicely explained in tutorial 6 opengl-tutorial.org . should start first tutorial of beginners tutorials , later intermediate tutorials . if you're going make win32 window can listen wm_keydown or wm_keyup messages , virtua
Read more