can we convert Audio (.mp3) to video (mp4) in android studio? how?

Question

i am new in this and i am working on App of media player and recording app. in which i have shown song list of device in the listview and recording start / stop / play. Now i want to convert that .mp3 recorded file into .mp4 and one image will show on behalf of a video in that file. Help me to achive this i have no idea and i refer many links and i didnt find anything.

Re: the second sample, looking just at the code, what is the value of `temp` at the moment you assign `b=temp;` If you're answer is, "I don't know", you're in good company because neither does your program. It invokes *undefined behavior* — WhozCraig, Jul 12 '18 at 06:35
it will returning the value of temp variable because your assigning b=temp and then printing it the second logic is wrong. — Ankita Mehta, Jul 12 '18 at 06:38
TBH `int a=10` looks fine, even in the class. What's the smallest program that causes the error, what's the exact errror? Instead of asking 3 bad questions, each of which is missing a lot, please ask 1 good question. — MSalters, Jul 12 '18 at 06:39
It might help of you focus your post on one single question, with an accompanying [mcve]. — juanchopanza, Jul 12 '18 at 06:40
You name a member function after your class??? If you want to write a constructor: these have no return values, i. e. you need to drop `void`. You might prefer the initialiser list against assignment: `swap() : a(10), b(20) {}` — Aconcagua, Jul 12 '18 at 06:42
*"\\cannot declare here"* - if you mean compiler complains and you cannot use *default initialisation*, maybe you are using an outdated compiler? Maybe you need to add appropriate compiler flags (e. g. GCC: one of `-std=c++11/14/17/0x/1y`, depending on version...). — Aconcagua, Jul 12 '18 at 07:02
@Drashti Add another question, you have edited the same question that you ask previously — HarshGiri, Jan 21 '19 at 18:21

score 1 · Accepted Answer · answered Jul 12 '18 at 07:08

Please check this link for your first question:
Why can't we initialize class members at their declaration?

Usually constructor is use to initialize value to data variables of class.

For 2nd Question: If data member is not initialize after creation of object, It will contain garbage value. So initialize or assign suitable value to as per your need.

Check below code:

#include<iostream>
using namespace std;

class swap_values
 {   
    int a, b, temp;
    public:
        swap_values(){
            a=0;b=0;temp=0;
        }
        swap_values(int x, int y){
              a = x;
              b = y;
              temp = 0;
           }

        void swapped()       
        {
            temp = b;
            b=a;
            a=temp;
        }
        void print(){
         cout<<"a: "<<a<<" b: "<<b<<endl;
         }
 };

int main()
{  
   int x =10; int y = 20;
   swap_values obj(x, y);
   obj.print();
   obj.swapped();
   obj.print();

   return 0;
}

can anybody help with this question? – Drashti Jan 18 '19 at 05:09 — Drashti, Jan 18 '19 at 05:09

score 0 · Answer 2 · answered Jul 12 '18 at 06:51

Everything can be done in better ways but just using your code this will work for you -

#include <iostream>

using namespace std;

class Swap  {

    private:
        int a,b,temp;

    public:

        Swap()
        {
            a=10;
            b=20;
            temp=0;
        }

        void swapNums()
        {
            temp=a; a=b; b=temp;
            cout<<a<<" " <<b<<endl;
        }
};

int main() {

    Swap s;
    s.swapNums();

    return 0;
}

You can avoid using class name as some function name. You can instead use constructor without a return type where you can initialise the member variables. swap method looks fine.

Joseph D. · Answer 3 · 2018-07-12T07:15:50.670

i am not able to initialize my variable in class.
 class swap
 {
      int a=10; \\cannot declare here
      int b=20; \\ cannot declare here
 }

Since C++11, this is fine, you can have default member initialization.
The error is due to missing semicolon after }.

why it has garbage value with b ??
a=b;
b=temp;
temp=a;

Since temp was never initialized before assigning it to b, temp has an indeterminate value. Any usage will lead to undefined behavior.

Here's a simple Swap struct:

 struct Swap
 {
     int a = 10; // default member initialization
     int b = 20; // default member initialization
     Swap(int a = 20, int b = 10): a(b), b(a) {}; // swap on initialization
                                                  // using member initializer list
 };

 Swap s;
 std::cout << s.a // 20
           << s.b // 10
           << std::endl;

In this example, default member initialization is "obsolete" / "redundant" due to member initializer list.

Suppose you should mention that now, with complete constructor, default initialisation just got redundant/obsolete... — Aconcagua, Jul 12 '18 at 06:58

can we convert Audio (.mp3) to video (mp4) in android studio? how?

3 Answers3