Which two statements are true about the digital audio in a VoIP network？（）

• A、Standard encoding techniques create an uncompressed digital data rate of 4000 bps.
• B、Standard encoding techniques create an uncompressed digital data rate of 8000 bps.
• C、Standard encoding techniques create an uncompressed digital data rate of 64，000 bps.
• D、Voice quality is not a concern if compression is not used.
• E、Two methods of quantization are linear and logarithmic.
• F、Two methods of compression are u-law and a-law.