Perceptual audio coding has become a widely-used technique for economic transmission and storage of highqualityaudio signals. Audio compression schemes, as known from MPEG-1, 2 and 4 allow encoding witheither a constant or a variable bitrate over time. While many applications demand a constant bitrate due tochannel characteristics, the use of variable bitrate encoding becomes increasingly attractive e.g . for InternetAudio and portable audio players . Using such an approach can lead to significant improvements in audioquality compared to traditional constant bitrate encoding, but the consumed average bitrate will generallydepend on the compressed audio material. This paper presents investigations into "two-pass encoding" whichcombines the flexibility of variable bitrate encoding and a predictable target bit consumption.
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