Technical Specifications
MPEG-1 Audio Layer II is defined in ISO/IEC 11172-3 (MPEG-1 Part 3)
- Sampling rates: 32, 44.1 and 48 kHz
- Bit rates: 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 and 384 kbit/s
An extension has been provided in MPEG-2 Audio Layer II and is defined in ISO/IEC 13818-3 (MPEG-2 Part 3)
- Additional sampling rates: 16, 22.05 and 24 kHz
- Additional bit rates: 8, 16, 24, 40 and 144 kbit/s
- Multichannel support - up to 5 full range audio channels and an LFE-channel (Low Frequency Enhancement channel)
The format is based on successive digital frames of 1152 sampling intervals with four possible formats:
- mono format
- stereo format
- intensity encoded joint stereo format (stereo irrelevance)
- dual channel (uncorrelated) format
Variable bit rate
MPEG audio may have variable bit rate (VBR), but it is not widely supported. Layer II can use a method called bit rate switching. Each frame may be created with a different bit rate. According to ISO/IEC 11172-3:1993, Section 2.4.2.3: To provide the smallest possible delay and complexity, the (MPEG audio) decoder is not required to support a continuously variable bit rate when in layer I or II.
Read more about this topic: MPEG-1 Audio Layer II
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