48 I see. Medium bitrates - Layer-2, low bitrates - Layer-3. What's about a bitrate of 96 kbps per channel that seems to be "somewhere in between" Layer-2 and Layer-3 domains? (MPEG Audio Layer-3 Applications)
Description
This article is from the MPEG FAQ, by Frank Gadegast phade@cs.tu-berlin.de with numerous contributions by others.
48 I see. Medium bitrates - Layer-2, low bitrates - Layer-3. What's about a bitrate of 96 kbps per channel that seems to be "somewhere in between" Layer-2 and Layer-3 domains? (MPEG Audio Layer-3 Applications)
Interesting question. In fact, a total bitrate of 192 kbps for stereo music is
useful for real applications, e.g. emission via satellite channels. The ITU-R
required that emission codecs should score at least 4.0 on the CCIR
impairment scale, even for the most critical material. At 128 kbps per
channel, Dolby's AC-2, Layer-2 and Layer-3 fulfilled this requirement.
Finally, Layer-2 got the recommendation mainly because of its
"commonality with the distribution and contribution application".
Further tests for emission were performed at 192 kbps joint-stereo coding.
Layer-3 clearly met the requirements, Layer-2 fulfilled them only
marginally, with doubts remaining during further tests with cascaded
codecs in 1993. In the end, the task group decided to pronounce no
recommendation for emission at 192 kbps.
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