Sound retrieval system

Olympus Digital Voice Recorder WS-321M with SRS-WOW-XT technology

Logo TruSurroundXT

TruBass logo

Logo Dialog Clarity

The Sound Retrieval System (SRS) is a proprietary technique of psychoacoustic audio signal processing on electronic consumer devices such as televisions, cell phones and computers. It was developed by what was then SRS Labs, Inc. , based in Santa Ana , California, and was discontinued under the brand name SRS when it was taken over by DTS , Inc., also from California , in 2012.

The concept is the psychoacoustic expansion of the stereo basis for stereo reproduction with loudspeakers and headphones as well as the interpolation of a surround sound from the stereo signal for multi-channel surround sound reinforcement . With the WOW feature , the bass signal in particular is expanded to counteract the acoustic compression from the production of the media and to restore the dynamics of the original sound source. In addition, the feature effects a psychoacoustic expansion of the stereo basis in the stereo reproduction with two loudspeakers through frequency-dependent phase shifts . The FOCUS (also Dialog Clarity ) feature effectively emphasizes the center signal in order to compensate for the acoustic hole between the loudspeakers and to restore the presence of, in particular, point sources of sound such as solo musicians. In the practical test, this feature is virtually equivalent to a center speaker in a multi-channel system. With the TruBass feature , overtones are added to the bass , which - in accordance with a registration practice with church organs - generate psychoacoustic undertones that could not be produced by the loudspeaker system itself. See also residual tone . The TruSurround feature combines the above features and makes use of the laws of the outer ear transmission functions : Further interventions in the phase position of the stereo signal by means of time differences and the generation of interaural level differences by manipulating the directional frequency bands result in phantom sound sources behind the head. Finally, the Circle Surround feature interpolates the stereo signal for playback on a 5.1 or 7.1 multi-channel system. In the practical test, if the parameters are carefully set using the SRS Audio Essentials or SRS HD Audio Lab software, there is a considerable tonal enhancement of inferior consumer boxes , the quality of which is characterized by pronounced resonances and nasal frequency humps due to the material and construction . The SRS Audio Essentials program with the Truvolume feature - in contrast to the SRS HD Audio Lab program - also offers a strong acoustic companding of the audio signal for the automatic adjustment of level differences within an audio file.

The software mentioned is still very popular on the Internet and is widely available for download. Both programs install the SRS HDAudio Lab Service under Windows and integrate a virtual SRS audio device. The software was also used as decoders for SRS-coded, dynamic Microsoft Smooth Streaming in 5.1 surround sound for the Microsoft Silverlight - client used. However, SRS 5.1 for Silverlight cannot be correctly decoded in the practical test on the Windows 7 operating system, neither via the SRS Audio Essentials software nor via SRS HD Audio Lab , since the virtual SRS audio device integrated into the system is not able to address the current drivers for the sound cards and assign the decoded stream to the surround channels. SRS 5.1 for Silverlight is no longer used because the Silverlight NPAPI plug-in is increasingly no longer supported and the sale and further development of the Microsoft Expression Encoder 4 Pro as an encoder for Microsoft Smooth Streaming with Silverlight client has been discontinued.