On 12/09/2018 19:03, Luiz Augusto von Dentz wrote: >> 2) Should we rather look at increasing quality of SBC codec in >> pulseaudio? And if yes, how should be quality of SBC configured? Via >> profiles? Or to invent some new protocol options? Can we increase >> default SBC bitpool allocation? > > I recall setting it to 64 before, but perhaps we are using 53 given > that most headset set that as maximum influenced by the spec suggested > values, I wouldn't go above 512kbit/s since then leave very little > room for any other traffic. I propose to use 76 bitpool as a default maximum (454.8 kbps for Joint Stereo, 44.1 kHz, 8 subbands, 16 blocks). This bitpool is optimal for both EDR 2 mbit/s and EDR 3 mbit/s modes, since it packs audio frames with least wasted bytes possible. EDR 2 mbit/s: up to 4 audio frames, 11.7 ms, 2 wasted bytes EDR 3 mbit/s: up to 6 audio frames, 17.5 ms, 14 wasted bytes. Note that Pulseaudio/bluez (not sure which) does not manage L2CAP MTU correctly. For EDR 2 mbit/s, MTU should be set to 679 (ignoring higher values upon negotiation), and EDR 3 mbit/s should use 1021 (right now something like 800 is used). > >> 3) If aptX is decided as useless, what about aptX HD codec? aptX HD >> codec is supported by less products (currently I do not own any), but >> this one may provide better quality as SBC according to that research. > > That is probably useful as something that provides a quality > improvement compared to SBC. > >> PS: That aptX research is the first and the only one about which I know. >> All other information about quality or other details which I found on >> internet are just marking informations. > > I had some suspicion before given that no manufacturer provided any > evidence aptX would beat SBC at the same bitrate, it is probably > better just because we are stuck at 53 bitpool with SBC while aptX can > probably have much higher bitrate. Anyway thanks to the researcher for > putting the time to evaluate the codecs we now have a good reference > for the quality each codec provides. > > >> -- >> Pali Rohár >> pali.rohar at gmail.com >> _______________________________________________ >> pulseaudio-discuss mailing list >> pulseaudio-discuss at lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss > > > -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 868 bytes Desc: OpenPGP digital signature URL: <https://lists.freedesktop.org/archives/pulseaudio-discuss/attachments/20180914/facb890e/attachment.sig>
