Editing ATRAC (section)

=== ATRAC (1) (versions 1.0–4.5, Type R/S) ===
ATRAC1 was first used in Sony's own theater format [[Sony Dynamic Digital Sound|SDDS]] system in the 1990s, and in this context is a direct competitor to [[Dolby Digital#Dolby Digital|Dolby Digital (AC3)]] and [[DTS (sound system)|DTS]]. SDDS uses ATRAC1 with 8 channel encoding, and with a total encoding rate over all the channels of 1168&nbsp;kbit/s.

Two stacked [[quadrature mirror filter]]s split the [[Signal (information theory)|signal]] into 3 parts:
* 0 to 5.5125&nbsp;kHz
* 5.5125 to 11.025&nbsp;kHz
* 11.025 to 22.05&nbsp;kHz

Full [[stereophonic sound|stereo]] (i.e., independent channel) encoding with a data rate of 292&nbsp;kbit/s.

High-[[frequency]] lowpass depends on the complexity of the material; some encodings have content clear up to 22.05&nbsp;kHz.

ATRAC1 can also be used in [[Monaural|mono]] (one channel) mode, doubling recording time.

[[FFmpeg]] has an implementation<ref>{{Cite web|url=http://git.ffmpeg.org/?p=ffmpeg;a=blob;f=libavcodec/atrac1.c;hb=HEAD|archive-url=https://web.archive.org/web/20110726052149/http://git.ffmpeg.org/?p=ffmpeg%3Ba%3Dblob%3Bf%3Dlibavcodec%2Fatrac1.c%3Bhb%3DHEAD|url-status=dead|title=Source code for ATRAC decoder|archive-date=26 July 2011}}</ref> of an ATRAC1 decoder.