This is an interesting discussion, especially for controller DJs looking for club slots. When you turn up to a club, you are often greeted with CDJs, a mixer and no room for your controller.
It would be unwise to move the gear. Particularly if you are a warm up DJ and the main act is expecting to arrive to a working setup, it's important to consider HID and Timecode. These are essentially ways in which you can DJ with both CDJs and your laptop.
The other reason you may be considering timecode or HID is because you want to look more professional and you feel your controller is inhibiting that look. This is not a bad thing, while controllers are becoming more acceptable, it looks way more professional to just plug in anywhere and play.
So let's first of all look at what both timecode and HID do. They both turn standalone DJ gear into a controller, of sorts, for using in conjunction with your laptop. They allow you to control your software with the gear you would find in a club, saving bringing all your CDs, vinyls, and controllers.
The basic function and premise is simple for both, but the way it is executed is very different for each one. I will be looking at them from a Serato standpoint but all in all the information is transferable. If you are a beginner however, double check that any hardware talked about here is compatible with your software.
Timecode is the first technology I will explore. It has the added benefit of working with turntables (vinyl) in addition to CDJs. If you are a scratch DJ looking to upgrade but keep using vinyl, then look no further as this is the one you need.
A typical Vinyl timecode setup using a Rane SL
Timecode works by playing a control CD or vinyl on the media player. It is a recording of clicks and sounds which tells the software what the playback state of the player is in. If you turn up the speed of the song on the CDJ, the timecode speeds up and tells the software to speed the song up by the appropriate amount.
If a timecode vinyl was scratched forward and backwards, the software knows the direction of playback and scratches the track accordingly.
There are different ways for the software to read the timecode information. Relative and Absolute modes allow for the DJ to choose whether they want to compromise the most real emulation of vinyl for the added safety of anti-skipping.
Worth watching if you are considering the timecode path.
There are issues with timecode however, you need to have timecode CDs or records for one, which are a pain if they get scratched. Unlike with a CD or a corrupt file, where you just use a different one, a broken control CD renders the CDJ useless. You can burn the timecode file onto a CD for spares, but with vinyl, you'd need to purchase more.
There is no screen feedback on the CDJs themselves either, all the information is limited to on the laptop, unlike in HID mode where the communication is two way, it is only the audio being sent from the CDJs to the laptop.
You also need a Serato compatible DVS box or controller such as the Rane SL boxes or the Akai AMX, the latter with a licence purchased as well.
This mode, standing for Human Interface Device, allows the CDJs to become controllers for the software. Serato has mapped out the main features of the CDJs to the software. This means, via USB connection, the CDJs buttons directly trigger the software.
It has the added benefit that all the information is available on the CDJ's screens, the tracks can be navigated without looking at the laptop.
The HID mode is limited to people who already have a Serato DJ activated controller connected so if you have a small controller, it is probably worth doing. If you only have a behemoth Numark NS7 or other large controller, you may as well just use that for playing instead of the CDJs.
The downsides to this is if you have limited USB ports, one has to be taken up by the connected controller, an issue for Macbook users.
This issue is saved slightly by Pioneer's newest CDJs and Mixer, the 2000 Nexus 2. It allows one USB connection to the pioneer mixer which all CDJs are connected to via Ethernet, however, these have been just announced and so for the general "public" it won't be much help.