Hello, Let me forward some comments from Frans de Bont, the inventor of SBC. He found a bug in the encoder but is not allowed to change the BlueZ implementation. Thus, I forward you his error description because these weeks I hardly have any time to look at the source code myself and - I have to admit - I am getting older and coding lazy. With best regards, Christian Hoene PS: Here Frans comments: I also have taken a quick look into the filtering part of the encoder. It seems that this code does not behave as the reference code. Unfortunately, I cannot disclose this part of the reference source code. However, if someone wants to correct this, the flow chart in the MPEG-1 Audio standard could be taken as an example with slightly difference parameters, i.e. subbands=32 and filterlength=512. You can find the referred flow chart in Figure C.4 on page 78 (in my version of the ISO/IEC 11172-3 standard). Please note that the decoder flow charts in A2DP have been derived from Figure A.2 on page 39. You can find ... public version on: http://www.mp3-tech.org/programmer/docs/iso11172-3.zip For the encoder filterbank, you can find this in annex_c.doc, page 13, FIGURE 3-C.2, "Layer I, II encoder flow chart". The decoder filterbank is shown in annex_ab.doc, page 2, Figure 3-A.3, "Layer III decoder flow chart". BTW, I noticed that earlier versions of the Bluez SBC codec are indeed based on the MPEG-1 flow charts. Probably the conversion from floating-point to fixed-point has introduced the quality degradation. Best regards, Frans ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Bluez-devel mailing list Bluez-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/bluez-devel
