On Tue, Mar 13, 2012 at 2:45 PM, qduaty <qduaty@xxxxxxxxx> wrote: > 2012/3/13 Siarhei Siamashka <siarhei.siamashka@xxxxxxxxx>: >> On Tue, Mar 13, 2012 at 3:48 AM, qduaty <qduaty@xxxxxxxxx> wrote: >>> 2011/10/18 Siarhei Siamashka <siarhei.siamashka@xxxxxxxxx>: >> Thanks for testing! One more experiment would be very much welcome. I >> wonder if just defining SBC_HIGH_PRECISION without doing anything else >> would have any noticeable effect on audio quality in listening tests. > > Well, before I move on, there is one thing that makes me sad: > > < ACL data: handle 1 flags 0x02 dlen 7 > L2CAP(d): cid 0x006d len 3 [psm 25] > AVDTP(s): Capabilities cmd: transaction 10 nsp 0x00 > ACP SEID 1 >> HCI Event: Number of Completed Packets (0x13) plen 5 > handle 1 packets 1 >> ACL data: handle 1 flags 0x02 dlen 16 > L2CAP(d): cid 0x0040 len 12 [psm 25] > AVDTP(s): Capabilities rsp: transaction 10 nsp 0x00 > Media Transport > Media Codec - SBC > 44.1kHz > Stereo > 16 Blocks > 8 Subbands > Loudness > Bitpool Range 112-128 > < ACL data: handle 1 flags 0x02 dlen 18 > L2CAP(d): cid 0x006d len 14 [psm 25] > AVDTP(s): Set config cmd: transaction 11 nsp 0x00 > ACP SEID 1 - INT SEID 2 > Media Transport > Media Codec - SBC > 44.1kHz > Stereo > 16 Blocks > 8 Subbands > Loudness > Bitpool Range 112-53 >> HCI Event: Number of Completed Packets (0x13) plen 5 > handle 1 packets 1 >> ACL data: handle 1 flags 0x02 dlen 8 > L2CAP(d): cid 0x0040 len 4 [psm 25] > AVDTP(s): Set config rej: transaction 11 nsp 0x00 > Media Codec > Error code 204 I'm only familiar with SBC codec in bluez, but not much with A2DP protocol. Maybe somebody else could comment. > The other device that tries to communicate at bitpool=112 and gives > up, is my phone. Now I'm listening to it with the headset and the > sound is perfectly clear, with no sign of that "analog" distortion I > mentioned earlier. Are you now comparing streaming of A2DP audio from your phone to your PC (using bluez A2DP sink) and to your bluetooth headset? > Bluez has MAX_BITPOOL=53 or 64 stored everywhere and who knows, maybe > it's even able to recover these magic numbers from bitrate. Should I > look for bitrate constant, like 320 or so? Maybe. If there is some problem negotiating optimal bitpool setting, then it is better to be fixed. >> audio quality in the current bluez sbc decoder is >> far from perfect and the synthesis filter needs to be replaced first. > > I'm not sure what you expect from sbcenc-sbcdec tests. Even if they > prove the encoding/decoding within Bluez has a reasonably good > quality, what then? Will it propagate among different devices, > bluetooth stacks? sbcenc-sbcdec tests are useful for testing bluez SBC codec. For any given bitpool value, encoding/decoding roundtrip should preserve as much audio quality as possible. And trying different possible combinations of encoder/decoder (bluez / reference sbc codec / bluetooth headset) should help to provide the answers to the questions you are asking. -- Best regards, Siarhei Siamashka -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
