Filtering total duplicates in object array

Question

I've created this filter:

app.filter('totalItems', function() { 

    return function (input) { 
        var total = [];
        input.forEach(function (value, key) {
            if (total.length > 0) {
                for (var i in total) {
                    if (input[key].descripcion == total[i].descripcion) { // 'descripcion' is an String
                        total[i].cantidad += 1; // 'cantidad' is a Number
                    } else {
                        total.push(input[key]);
                    }
                }
            } else {
                total.push(input[key]);
            }   
        });
        return total; // It's returning just an empty array. Why?
    }
});

For this view:

<table>
<tr>
    <th>Descripcion</th>
    <th>Precio</th>
    <th>Cantidad</th>
</tr>
<tr ng-repeat="(key, value) in tempCart | orderByPriority | totalItems">
    <td class="ar"> {{ value.descripcion }} </td>
    <td> {{ value.precio | currency: 'BsF.' }}</td>
    <td> {{ value.cantidad }} </td>
</tr>

Using this controller:

app.controller('cartController', ['$scope', '$firebase', function(sp, fb) {

    var userSessionRef = new Firebase('https://XXXXX.firebaseio.com/development/user_sessions/uid/');
    sp.tempCart = fb(userSessionRef);
}]);

(The reference looks like this)

The idea of the filter is to sum similar items and return an array with the total; if there are three objects that have 1 apple, the filter should return one object with 3 apples. But none of my tries have been successful.

What could be wrong?

Thanks in advanced.

EDIT:

Thanks to this, I've changed the filter for a simplest one:

app.filter('totalItems', function() {

    return function (input) { 

        var output = [],
        found,
        x = 0, 
        y = 0;

        for ( x = 0; x < input.length; x++ ) {
            found = undefined;
            for ( y = 0; y < output.length; y++ ) { 
                if ( input[x].id === output[y].id ) {   
                    output[y].cantidad += 1; // This line is causing a "$digest() iterations reached" error.
                    found = true;
                } 
            }
            if ( !found) {
                output.push( input[x] );
            }
        }
        return output;
    }    
});

The function works great but not the filter; it's producing this error:

Error: $rootScope:infdig Infinite $digest Loop

I haven't found a way to solve it even though I've read this explanation... Honestly, I don't know what could I do.