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Technologies

SoundCode For Dolby E features many technologies used in professional audio environments. This section describes them.

Dolby E

Dolby E technology was developed by Dolby Laboratories to transport audio and metadata on digital videotapes or AES cables using two channels of PCM audio. Up to eight channels of audio and metadata are encoded by a Dolby E encoder, which outputs a Dolby E stream that is two channels of PCM audio.

Do not listen to a raw Dolby E stream at high volume

If you listen to a Dolby E stream you will hear loud bursts of noise that can damage your hearing or speakers at high volume. A Dolby E decoder processes the stream to output the original encoded audio and metadata.

Dolby E is often used to deliver audio and metadata on a digital videotape for television broadcasting. The audio being delivered (a 5.1 surround mix, for example) is first Dolby E encoded to a Dolby E stream and recorded to two audio channels of the videotape. The tape is played back by a broadcaster and fed to a Dolby E decoder, which outputs the 5.1 surround mix and metadata. Often, the decoded audio and metadata is connected to a Dolby Digital encoder used in ATSC and digital cable television broadcasting.

SoundCode For Dolby E features a Dolby E Encode option and a Dolby E Decode option for use on nonlinear audio and video workstations:

  • The Encode option Dolby E encodes audio and metadata to a stereo WAV file that carries the Dolby E stream. The stream can then be recorded to a video tape or stored as a file for delivery to a broadcaster.
  • The Decode option decodes a Dolby E stream for editing or quality-assurance testing.

BWF Files

BWF files are WAV files that can hold up to eight channels of audio, Dolby metadata, and BEXT metadata in a single file. Dolby metadata contains important information for broadcasting — such as how loud the audio is, how it should be downmixed to stereo, and the audio stem format.

Because a single BWF file holds both the audio and the metadata, it is a very convenient format for delivering and receiving audio between workstations and facilities. For example, a mixing engineer can make a 5.1 mix and a stereo mix of a television program, package the two mixes and the Dolby metadata into a single file, and send it to a facility for Dolby E encoding.

BWF files contain a Dolby metadata "chunk" that specifies the metadata. The metadata chunk applies to the entire file — BWF files are not capable of having metadata that changes over time.

Dolby DP600

The Dolby DP600 is a hardware product manufactured by Dolby that implements file-based processing of many Dolby technologies, including Dolby E, Dolby Digital, Pro Logic, and loudness measurement/correction.

SoundCode For Dolby E implements actual Dolby E encoding and decoding, so it is not necessary to use a DP600. But if you are using a DP600, it uses BWF files for input and output. A single BWF file can hold up to eight channels of PCM audio and Dolby E metadata, and SoundCode For Dolby E can read and write BWF files — allowing you to interface your audio/video workstation to a DP600.

RF64 Files

RF64 files are WAV files that can be larger than 4 GB. (Pro Tools does not support files larger than 2 GB as of version 8.0.) An RF64 WAV file can also include additional WAV "chunks" that define additional features such as BWF.