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Audio editing with double system audio

One of the workflows that we support in Forscene is Double or Dual System Audio – but what is this and why is it important?

Dual System Audio is simply where picture and sound have been recorded onto two different devices (or systems). In the early days of film the camera had no way to record audio so all sound was recorded onto separate audio recorders. The classic Nagra tape recorder is a masterpiece of Swiss precision engineering and was used on film shoots for many years. Even today audio is recorded separately on film shoots but now it is usually recorded digitally.

The crucial thing about double system audio is that the picture and sound recording devices have to be able to run at the same speed and there has to be a way to synchronise the two recordings. At the simplest level the classic film clapperboard is a visual and audio reference point, which can be used to sync the rushes, but nowadays almost everything is synchronised using timecode, often sent wirelessly between the camera and the audio recorder.

When video cameras first became common in the 1970’s they had the ability to record sound “in camera”, which meant that the tapes that recorded the pictures also carried the sound, so none of this was necessary. For years programs shot on tape used the same media to record pictures and sound.

With the arrival of low cost digital cameras such as the Canon 5D we have gained the ability to shoot very high quality images, but often the onboard audio recording capabilities are very limited. This has led to a return to separate audio recording and so Dual System Audio has become much more important.

Reality TV shows are a good example, with multiple cameras such as GoPro’s shooting video and multiple audio recorders used to record each cast member. Getting everything into an editing system in sync and in a format that the editor can work with has become a very complicated process.

In a typical post-production workflow the following steps would have to take place:

1: Digitisation of all video material, with guide audio if available.

2: Transcoding of all video material to an acceptable format and quality for editing.

3: Digitisation of all audio material, transcoding to a common format if necessary.

4: Synchronisation of all video and audio material, either by timecode or manually if no timecode is available, checking that sync does not drift over the course of a long recording.

At this stage you will have already filled a lot of your storage and if you are just beginning a long editing process your media will be tying up that storage for some time. It has quite possibly taken you days to get everything digitised and synchronised.

5: Ingest to Forscene for viewing, logging and editing.

6: Edit your material in Forscene

How far you take the edit in Forscene is up to you but once the editing process is complete you will want to export an AAF, XML or EDL to go back to the finishing suite.

7: Conform and finish the edit.

As you can see this is a complicated process and there are many stages that cost time and money in terms of storage and personnel. However, if you choose to do all your synchronisation in Forscene the process can be reduced to the following steps:

1: Ingest video material with guide audio into Forscene (automatically transcoding to Forscene’s lightweight proxy, this can be done as part of the backup process for Digital media)

2: Ingest audio material into Forscene (again as part of the backup process)

3: Synchronise all video and audio material in Forscene, either automatically by timecode or manually if no timecode is available, checking that sync does not drift over the course of a long recording.

4: Edit your material in Forscene.

5: Export an AAF, EDL or XML for your online suite, this allows you to digitise only the media that you have used in your edit. Confom and finish your edit in the online suite.

Not only does this workflow streamline the post-production process and reduce the need for all media to be digitised, it allows all members of the production team to have access to the media as it is being loaded, from anywhere with an internet connection.

By working in this way the time taken to arrive at the first cut can be drastically reduced. Team members can collaborate easily no matter where they are located and feedback can be sent to the editors quickly and easily.

If you have any comments or would like more information on how to work with Dual System Audio in Forscene, then sign up for a free demo at IBC.



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