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Sound Blaster Live! is a sound card from Creative Technology Limited. It is a PCI add-on board for PCs. ==Overview== Sound Blaster Live! (August 1998) saw the introduction of the EMU10K1 processor, a 2.44 million transistor audio DSP, rated at 1000 MIPS. The EMU10K1 featured hardware acceleration for DirectSound and ''EAX'' 1.0 and 2.0 (environmental audio extensions), a high-quality 64-voice MIDI sample-based synthesizer, and an integrated FX8010 DSP chip for real-time digital audio effects. A major design change from its predecessor (the EMU8000) was that the EMU10K1 used system memory, accessed over the PCI bus, for the wavetable samples, rather than using expensive on-board memory. This was possible at this point because systems were being equipped with far more RAM than previously, and PCI offered far faster and more efficient data transfer than the old ISA bus. The integrated FX8010 was a 32-bit programmable processor with 1 kilobyte of instruction memory. It provided real-time postprocessing effects (such as reverb, flanging, or chorus). DSP effects in the older SB/AWE family were restricted to MIDI synth, but in the SB/Live family, the EMU10K1's integrated FX8010 operated on any source. This capability let users select a pre-defined listening environment from a control-panel application (concert hall, theater, headphones, etc.) It also provided hardware-acceleration for ''EAX'', Creative's environmental audio technology. The Effect algorithms were created by a development system that integrated into Microsoft Developer Studio. The effects were written in a language similar to C, and compiled into native FX8010 object code by its compiler, ''fxasm''. The ''Sound Blaster Live!'' featured higher audio quality than previous Sound Blasters, as it processed the sound digitally at every stage, and because of its greater chip integration that reduced the analog signal losses of older, larger cards. Unfortunately, digital processing brought some limitations. The DSP had an internal fixed sample rate of 48 kHz, a standard AC'97 clock, meaning that the EMU10K1 always captured external audio-sources at the 48 kHz, then performed a sample-rate conversion on the 48 kHz waveform to the output the requested target rate (such as 44.1 kHz or 32 kHz). This rate-conversion step introduced intermodulation distortion into the downsampled output. The SB/Live had great difficulty with resampling audio-CD source material (44.1 kHz) without introducing audible distortion. Creative addressed this concern by recommending audio-recording be performed exclusively at 48 kHz, and use third-party software to handle the desired sample-rate conversion, to avoid using the EMU10K1's sample-rate conversion. Sound Blaster Live! supported multi-speaker output, initially up to a 4-speaker setup. The software referred to this as a "4.1" setup, meaning 4 satellites and a subwoofer. While this is the case, the subwoofer is not on a separate output as it is with 5.1 and higher audio. Instead, a low-pass filter (crossover) within the speaker system removes high and midrange frequencies from the sound card's output for the subwoofer. Games see a "4.1" speaker system as quadraphonic because DirectSound itself offers no subwoofer output in this configuration. This is not limited to Creative sound cards; Aureal, Ensoniq, Philips, and other manufacturers have made cards that use four-speaker output in the same fashion. Later versions of the Live!, usually called ''Live! 5.1'', offered 5.1-channel support which adds a center-channel speaker and LFE subwoofer output, most useful for movie watching where Dolby Digital 5.1 is decoded. The Live! implemented DOS legacy support via Ensoniq's AudioPCI DOS TSR program. Creative acquired Ensoniq in 1998 and, as part of the deal, made use of this highly-compatible ISA sound card emulator with their newer cards. In fact, the Live! uses ".ecw" (Ensoniq Concert Wavetable) files for the wavetable emulation in DOS. The program enables support for many standards, such as Sound Blaster 16, General MIDI, AdLib (OPL3), among others. Sound Blaster Live! was the first sound card from Creative with the "What U Hear" recording input channel. This was supported in the Windows drivers, so no additional software was needed to utilize it. The analog stereo audio signal that came out of the main Line Out was directed into this input. That way, one could mix all available inputs and the MIDI synth into one stereo signal. When using "What U Hear" with 5.1 sound, the sound would be downmixed to stereo first. The Creative Recorder utility included with the sound card was specifically designed to take advantage of the "What U Hear" feature, making it a simple matter to capture streaming sound from any source, even from programs that deliberately avoid providing a means for saving the digital sounds, thus freeing non-technical users from the complexities of "patching" between inputs and outputs of various software modules. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sound Blaster Live!」の詳細全文を読む スポンサード リンク
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