Tech Blog – The Dolby E Guard Band

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Paul Neyrinck discusses the Guard Band in Dolby E Streams

Dolby E is a data stream that is carried as stereo PCM audio.  It is always used together with video on a video tape or in a MXF or Quicktime movie file and is an encode of one or more mixes of the program.

Typically, it is an encoding of a 5.1 mix and a stereo mix. The PCM audio is divided into frames, one for each video frame.  But the data doesn’t fill up the entire PCM audio stream.

If you look at a Dolby E stream in an audio editor you will see gaps of silence between bursts of data.  The silent portion of audio between the start of the video frame and the start of the burst is called the guard band. The guard band is there so editing programs can edit the audio on video frame boundaries without affecting the Dolby E data.

A common question is “where should the Dolby E stream be placed to have the correct guard band?”  The good news is that the Neyrinck SoundCode For Dolby E encoder automatically inserts the guard band according to Dolby standards so you don’t have to worry about it.

The WAV file is time-stamped so it is sample accurately placed into any workstation software.  If you are interested in learning more about the guard band placement, follow the link below to Dolby’s web site for some nitty-gritty details.