They are much more advanced audio formats compared with PCM audio. The SigmaTel audio chip in the Inspiron 8500 is able to generate this digital audio itself and output it over the S/PDIF link.ĪC-3 and DTS are audio formats typically stored on DVD discs.

It does not incorporate any complex compression algorithms which means very little technology is needed to encode and to decode it. An external Dolby Digital/DTS decoder and speakers must be connected to the S/PDIF port to play this audio.Īs far as I know, PCM audio can be thought of as 'dumb' digital audio. The audio sent in this mode is not generated by the chip, rather the audio signal is sent into the chip and the chip passes the digital audio stream out through the S/PDIF port. This data can be PCM, MPEG, AC-3, DTS, or other format. The AC'97 2.2 specification refers to this as 'mixed mode' operation for 'mixed data originating from the OS mixer service'.ĪC'97 2.2 also requires that the codec be able to operate in a 'pass-thru' mode for 'data originating from an independent S/PDIF source'. The digital audio is sent in digital PCM format through the laptop's S/PDIF port. The analog audio is sent to the internal speakers or headphone jack on the computer. When the laptop is playing stereo sound normally, it will output it simultaneously in both analog and digital form. This specification defines various modes of operation for the audio chip, and defines some minimum functionality that the chip must incorporate in order to fulfill the requirements of the specification. This chip complies with an audio chip specification defined by Intel in particular, it complies with the Intel AC'97 v2.2 specification. The Inspiron 8500 audio chip is made by a company called SigmaTel, and the model of the chip is STAC9750. Anyway, here's what I've uncovered so far.

I haven't bought a set of surround sound speakers yet to test my theory, but I'm hoping someone else has and can test it to shed some light on the matter. I have observed many conflicting opinions on this subject in various threads so I decided to do some research on the subject and start a thread of my own.įirst of all, I believe it is possible to output 5.1 surround sound audio directly from the S/PDIF port on Inspiron 85 laptops and possibly other models too.

I would like to connect a set of 5.1 surround sound speakers directly to my Inspiron 8500 for watching DVDs.

Ac 97 audio dolby 5.1 driver