What is the difference between Dolby Pro Logic II and Dolby Digital?
Scope
Dolby Digital is a lossy data compression method. It must be decoded back into “normal” PCM or Pulse Code Modulated audio on playback. Dolby Digital is used for DVD-Video, settop boxes, and DTV. It cannot be used without a Dolby Digital decoder. If it is not decoded, it will play the AC-3 data as unrecognizable “noise” which, if the playback gain is turned up, could blow your speakers or ears!
In comparison to Dolby Digital, Dolby Pro Logic II is a “matrix” encoder that uses only analog processes, like phase shift and filtering, to conceal the surround information within the stereo audio. Although not discrete like Dolby Digital, Dolby Pro Logic II-encoded audio can be played on any stereo system. If there is a Pro Logic II decoder, it will "unfold" the hidden surround out of the stereo signal and provide Dolby Surround.
Let us know how we can help
If you have further questions on this topic or have ideas about improving this document, please contact us.
