src/Assetic/Factory/NamespaceAwareAssetFactory.php
protected function parseInput($input, array $options = array())
    {
        $matches = null;
        // search for @MyNamespace/path/to/asset
        if (preg_match("|^\@([a-z_][_a-z0-9]*)/|i", $input, $matches)) {
            $ns = $matches[1];
            if (!array_key_exists($ns, $this->namespaces)) {
                throw new \RuntimeException("$ns : unknown namespace !");
            }
            $input = $this->namespaces[$ns] . substr($input, strlen($ns) + 1);
        }
        return parent::parseInput($input, $options);
    }
protected function parseInput($input, array $options = array())
    {
        $matches = null;
        // search for @MyNamespace/path/to/asset
        if (preg_match("|^\@([a-z_][_a-z0-9]*)/|i", $input, $matches)) {
            $ns = $matches[1];
            if (!array_key_exists($ns, $this->namespaces)) {
                throw new \RuntimeException("$ns : unknown namespace !");
            }
            $input = $this->namespaces[$ns] . substr($input, strlen($ns) + 1);
        }
        return parent::parseInput($input, $options);
    }
Will detect inputs that begin with @MyNamespace/... and replace the namespace with the corresponding path.

@see \Assetic\Factory\AssetFactory::parseInput()