celt: celt (The CELT ultra-low delay audio codec) celt: celt: The CELT codec is an experimental audio codec for use in low-delay celt: speech and audio communication. celt: celt: CELT stands for "Constrained Energy Lapped Transform". celt: It applies some of the CELP principles, but does everything in the celt: frequency domain, which removes some of the limitations of CELP. celt: celt: CELT is suitable for both speech and music