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------ Hello! Recently I had tested Codec2 on audio samples on both English and Russian languages, using MELPe as a reference. Moreover, I used three noise modes: no noise at all, gaussian noise and voice noise (e.g. when you are talking in a crowded room). As I don't have a source code for MELPe 600, I had tested only 1200 and 2400 bitrates. Some of MELPe tests were repeated in a environment where encoder and decoder processes were separated to ensure that no audio information is leaked through internal buffers and structures. To my disappointment, however, Codec2 performed much worse than MELPe, producing yet still intelligible (in some cases), but heavily distorted result. I made page with original and encoded samples: https://m-k.mx/static/codec2/. I am surprised why Codec2 performs so bad even on high bitrates where MELPe produces almost identical audio without any audible artifacts. Codec2 also degrades significantly on non-English samples (VQ codebooks are fine-tuned for English?). While degradation at noisy samples is expected (especially in voice noise), Codec2 sometimes produces very distorted and hardly intelligible results, while MELPe exhibit only slight degradation. So my questions are: 1. Are my experiments correct? Maybe I'm missing something important, like equalizer in front of Codec2 (--eq option appears to have no impact on the quality). 2. Are high-bitrate modes like 2400 and 3200 still up-to-date? I have seen a lot of effort put into 700C mode, but sometimes high-bitrate modes are useful as well. _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
