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Lesson Plan 1

Time required: Approximately 1 hour

Welcome to the Source-Connect lesson plan! In this first lesson we will cover the historical development of remote recording, and look at some examples of how today’s collaboration happens and under what contexts. We’ll also cover the basics of networking and do an experiment in breaking the Internet.

Lecture: Historical context

What is the historical context for remote recording over IP? When did it start and why?

It is not always possible to have the specific talent and the creatives in the same place at the same time to do their work together, this doesn’t help to keep creative and technical process fluid – for example, after film production ends, actors may go home to a remote location or go to shoot another movie, while there is still work to be done with the dialog tracks. As technology has improved, the industry has found greater flexibility to deal with these remote working situations and options that even allow for better cost and time management, as progress continues to develop new and interesting ways of collaborating.

It’s hard to say when the first “remote session” was first accomplished. Working remotely started first by either using a courier service to shuttle recorded material around the country/world or air travel to bring the creatives and talent together. Very quickly the use of a low quality phone connection to monitor a session was used where master materials were then couriered to their proper destination. Then in the very late 70’s and early 80’s GlobeCast satellite connections and digital codecs became available making truly remote better than telephone quality audio connections possible. Codecs are devices that convert high bandwidth audio and video signals to low bandwidth signals that are more easily transported over digital networks. Sometimes these recordings were used as masters and other times the true master was sent via a courier after the session was complete. This was quickly followed in the middle 80’s up to the current time with land line based ISDN (basically digital telecommunications lines direct to the consumer) connectivity and new generation codecs making remote sessions much more cost effective and therefore common. With this “ISDN” workflow firmly in place by the late 90’s and with the internet gaining in speed and ubiquity along with computer technology exponentially gaining in capability an even more cost effective and more flexible method of working remotely emerged. The first widely used computer/internet based codec was introduced in 2005 by Source Elements who released Source-Connect which uniquely was designed as a plugin to operate directly within Pro Tools, the predominant workstation being used. Though there were new hurdles to cross in order to make the internet work as much like ISDN as possible, the path was clear and Source-Connect became the default method of accomplishing remote sessions for a large part of the pro audio community. At the same time most telco companies decided to deprecate and in time finally discontinue their landline TDM services including ISDN prompting companies who traditionally made ISDN based systems such as Telos, Tieline to promote new generation IP based systems all speeding the move towards an all IP/internet workflow for remote sessions.

Lecture: Current technology

At the time of writing this, ISDN is still a very popular option. ISDN is often picked for various reasons. 1- large incumbent network. 2- typically more stable/lower latency connections compared to the public internet. 3- better data security due to the nature of the ISDN network. However, ISDN has many drawbacks and limitations that overshadow the legacy advantages to ISDN. 1- ISDN is much more expensive to maintain and use the lines, where minute by minute charges apply; sometimes these charges are more than $1/min and greatly more for international connections. 2- except for the most unique systems, ISDN is limited to 128kbps (stereo or mono) 3- again except for very unique systems, ISDN must use one of its audio channels to transmit time code if sync is required.

By the late 80’s the audio industry settled on a few common codec configurations for various tranches of users. For example in the post production industry Mpeg Layer2 128kbps mono or stereo connections became the norm while for many radio stations single 64kbps G.722 connections were more popular. Jumping to the early 2000’s on the IP side such a common denominator setup had not been established and as of the writing of this article still has yet to truly emerge. Efforts (mainly between the legacy ISDN codec manufactures) such as the NACIP standard have attempted to establish a common method of connecting between IP codecs but again they have not taken significant hold specifically in the post production industry and so the majority of IP connection remain proprietary, often requiring the same hardware/software on both sides of the connection. Of these proprietary types of connections one of the more popular types especially in the post production and voice over tranches continues to be Source-Connect.

Technology continues to move forward and in some cases consumer tech such as Skype or various browser based audio/video chat systems have increased in audio quality and are often of good enough quality for some professional purposes, though theses systems do often show qualities more designed for general communications or intelligibility and are not specifically geared towards true audio fidelity or they do not interface easily with professional audio systems and software.

Specifically Source-Connect provided several unique post production centric features which have likely helped build its popularity in those circles. Examples of such features include the Q Manager which has the ability to guarantee the delivery of every packet to the remotely recorded audio files even if it didn’t arrive on time in the real time recording process. Thus any dropouts that may occur are not permanent in the recording and can be fixed automatically (Auto Restore) immediately once the recording is stopped. Furthermore, the Q Manager’s Auto Replace feature makes it possible for an entire session’s worth of remote recordings and all edits using those recordings to be automatically updated with the uncompressed audio or lossless audio thus removing any audio degradation due to the codec processing. Also the RTS (Remote Transport Sync) system built into Source-Connect makes it possible to synchronize the timelines of the remotely connected systems allowing for remote mixing with picture sync, ADR/read to picture, musical overdubbing and other more advanced post production oriented workflows.

Discussion: Remote workflows

Consider the following remote audio workflows and discuss possible solutions

  • Remote recording of a voice over artist without time lock
  • Remote recording or simply connecting with multiple participants for a radio/podcast interview
  • Remote recording with time lock for Dialog Replacement (ADR) or musical overdubbing
  • Remote monitoring of a mono to 7.1 surround mix session with or without picture/time lock
  • Studio to Transmitter link (STL) for radio broadcasting.

Lecture: Introduction to Networks

In the current implementation of the Internet, we cannot each have an individual address because there are more computers on the network than there are possible numbers: this is what is known as the “IPv4 address space” (pronounced eye pee vee four). An IPv4 address looks like: aaa.bbb.ccc.ddd except using only numbers from 0 to 255. So this means, you cannot have more than 4,294,967,296 addresses, or just over 4 billion. There were more than 600 millions iPhones, and over one billion Android phones shipped just last year! So you can imagine, if we include all the computers that ever connected to the internet including phones and other kinds of devices, 4 billion addresses isn’t enough. So to manage this, we use Routers which can create more networks behind a network: for each address, say 1.xxx.xxx.xxx, we can add another 16 million addresses behind it (255 x 255 x 255). This is how the modern Internet works, but it poses a problem: it means that my computer address is not the “public” address, because my network is behind a Network Address Translator, or NAT. It can cause some problems to connect, especially if you also have a strict firewall that blocks incoming or outgoing traffic that hasn’t been previously authorized. Fortunately we have many ways to resolve the NAT problem, and you shouldn’t encounter any issues during your experiments with Source-Connect.

Firewalls are also very common, especially on Windows machines where there are common vulnerabilities. Unix-based systems such as Mac OSX are less vulnerable, and usually have the Firewall disabled, however under Corporate networks you will often find strict firewalls to protect from intruders.

Source-Connect software will try several methods to route audio to you, even if you have a firewall or complex NAT situation. Sometimes it may fail, however, and you will need to ask for I.T. support from your network supervisor.

Action: Working with Source-Connect

  • Source-Connect should be able to establish a test connection with one of the Echo services. Does this connect successfully? If not, what can be done to resolve this?
  • Go to your System Preferences->Security and enable the Firewall, then Block all incoming connections under the ‘Firewall Options’ button. When you run the Port Test button in Source-Connect it will no longer be successful. Can you still make a connection?
  • When you are connected, gradually take the laptop out of the room and as far away as possible. When does the connection start to break up? What does it sound like?
  • Install Apple’s Network Link Conditioner and simulate different kinds of packet loss. Can you saturate your bandwidth by watching Youtube, playing Twitch.tv or downloading a file or torrent?
  • Connect using a cellphone connection, slowly wrap the cellphone in silver foil layers (or a Faraday cage if you have one)
  • Advanced: Send a sine-tone signal from the laptop and record it on the other side of the connection. As you make the network break, you will be able to see what packet loss looks like, by zooming into the recorded file. Using a sine-tone makes it really easy to see the packet loss.


  • How would you manage a situation where bandwidth or technical issues cause problems during a session?
  • How would this be a different problem, depending if it was a live radio session or tv broadcast, versus a post-production session where you have time to recover?
  • What kind of emotional experience would this be for the participants when there is limited time, or you are working with famous actors or musicians, or people who are not comfortable with technology?

A quick note: when connecting, you will see a blinking orange Receive light. If that light is not blinking it means there is no network data received and it will because of a NAT or Firewall problem. Your learning advisor can contact Source Elements for help (or you are welcome to contact us too!)