On 17/09/16 18:28, glen english wrote: > Yeah. > > Cascading codecs is always trouble. > > BTW My understand of the word TRANSCODING is going between one encoded > method and another without going back all the way to uncompressed. Going > between different video encoding methods usually done by transcoding. > Most video encoding is all DCT / macroblock based so is probably more > relationship between codecs than speech codec variations.... > > > In this problematic voip case: uncoded PCM (microphone) >> AMBE2 >> > over air >> decoded >> PCM >> uLaw encode>> ulaw decode >> headset. (and > reverse) .
Transcoding is going from one format to another, and when the destination is a lossy format, that will mean a reduction in quality. Decoding to uncompressed shouldn't incur loss compared with a hypothetical conversion from AMBE2 direct to µ-law, more likely the assumptions made by the µ-law CODEC don't hold true for the synthesized voice from the AMBE2 CODEC, and that would be why it sounds so terrible. Regards, -- Stuart Longland (aka Redhatter, VK4MSL) I haven't lost my mind... ...it's backed up on a tape somewhere. ------------------------------------------------------------------------------ _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
