Sound Recording Solutions
Sound Card Recorder
Powerful voice activated microphone recorder for Windows. Click here to learn more.Advanced Audio Coding
Advanced Audio Coding (AAC), also known as MPEG-2 Part 7, and also MPEG-4 Part 3 in a slightly modified form, is a digital audio encoding and lossy compression format. It was popularized by Apple Computer through its iPod and iTunes Music Store. AAC was designed as an improved-performance codec relative to MP3 (which was specified in MPEG-1) and MPEG-2 Part 3 (which is also known as "MPEG-2 Audio" or ISO/IEC 13818-3). AAC was promoted as the successor to MP3 for audio coding at medium to high bit rates. AAC is a wideband audio coding algorithm that exploits two primary coding strategies to dramatically reduce the amount of data needed to convey high-quality digital audio. Signal components that are perceptually irrelevant are discarded. Redundancies in the coded audio signal are eliminated. The signal is then MDCTed according to its complexity. Internal error correction codes are added. The signal is stored or transmitted. MPEG-4 audio standard does not require a single or small set of highly efficient compression schemes but rather a complex toolbox to perform a wide range of operations from low-bit-rate speech coding to high-quality audio coding and music synthesis. The MPEG-4 audio coding algorithm family spans the range from low bit-rate speech coding (down to 2 kbit/s) to high-quality audio coding (at 64 kbit/s per channel and higher). AAC has the sampling frequencies between 8 kHz and 96 kHz and any number of channels between 1 and 48. In contrast to MP3's hybrid filterbank, AAC uses the modified discrete cosine transform (MDCT) together with the increased window lengths of 2,048 points. AAC is much more capable of encoding audio with streams of complex pulses and square waves than MP3 or Musicam. AAC can be switched dynamically between MDCT block lengths of 2,048 points to 256 points. If a single change or transient occurs, the short window of 256 points is chosen for better resolution. By default the longer 2,048-point window is used to improve the coding efficiency. AAC takes a modular approach to encoding. Depending on the complexity of the bitstream to be encoded, the desired performance and the acceptable output, implementers may create profiles to define which of a specific set of tools they want use for a particular application. The standard offers four default profiles: Low Complexity Profile (LC) - the simplest and most widely used and supported. Main Profile (MAIN), which expands upon LC with backwards prediction. Sample-Rate Scalable (SRS) is also called Scalable Sample Rate (MPEG-4 AAC-SSR) in line with the standard nomenclature. Long Term Prediction (LTP), added in MPEG-4, an improvement of the MAIN profile using a forward predictor with lower computational complexity Depending on the AAC profile and the MP3 encoder, 96 kbit/s AAC can give nearly the same or better perceptional quality as 128 kbit/s MP3. Applying error protection enables error correction up to a certain extent. Error correcting codes are usually applied equally to the whole payload. But since different parts of an AAC payload show different sensitivity to transmission errors, this would not be a very efficient approach. The AAC payload can be subdivided into parts with different error sensitivities. Independent error correcting codes can be applied to any of these parts using the Error Protection (EP) tool defined in MPEG-4 Audio. This provides the error correcting capability just the most sensitive parts of the payload in order to keep the additional overhead low.
Phone Call Recorder
Must have software for voice modem. Record all phone calls automatically, watch Caller ID information, create you own powerful answering machine. Perfect sound quality. Click here to learn more.3d audio effect - 3gp - a-law - aac - acm - adc - aiff - aliasing - amplifier - amr-wb - amr-wb plus - amr - apev2 tag - asf - atrac - audio codec - audio compression - avi - bitrate - bitrate peeling - chord - codec - comfort noise - compact audio cassette - compact disc - compression - compression artifact - compression ratio - contact microphone - container format - dab - data compression - digital audio - digital camera - divx - dolby digital - dolby digital plus - dsp - dvd-audio - dvd - effects unit - equalization - ffmpeg - flanging - fourcc - frequency spectrum - hi-fi - high-end audio - hiln - id3 - joint stereo - laser microphone - line level - lossy - loudspeaker - matroska - mcf - microphone - midi - mixing console - mp2 - mp3 - mp3 surround - mp3 sx - mp3pro - mp4 - mpeg-1 - mpeg-21 - mpeg-3 - mpeg-4 - mpeg-7 - mpeg - mu-law - musepack - music - mxf - nut - osm - parabolic microphone - pcm - perception - phonograph - pink noise - pqf - psychoacoustics - qdesign - quadraphonic - radio receiver - ratdvd - realaudio - red noise - reverberation - rhythm - ribbon microphone - riff - rmvb - sbr - signal processing - sound - sound card - sound effects - sound recording - spdif - speech encoding - speech recognition - speex - stereo - subwoofer - surround sound - synthesizer - tape recorder - tdm - tweeter - video - video compression - vob - voice analysis - vorbis - wav - white noise - wma - woofer