[pulseaudio-discuss] SBC XQ for PA 13.0

Hyperion h1p8r10n at yandex.com
Mon Dec 9 12:53:31 UTC 2019

09.12.2019, 12:47, "Andrey Semashev" <andrey.semashev at gmail.com>:
> On 2019-12-09 14:39, Pali Rohár wrote:
>>  On Monday 09 December 2019 14:32:52 Andrey Semashev wrote:
>>>  I have another piece of feedback to provide. Sometimes I experience audio
>>>  dropouts. Sometimes in both left and right headphones, sometimes just one.
>>>  In particular, I noticed this happen when I have a Bluetooth-connected
>>>  DualShock 4 gamepad connected and playing games, but it also happens without
>>>  it, although less often.
>>>  I assume this is caused by Bluetooth bandwidth limitation. Note that EOZ Air
>>>  are "truly wireless" (i.e. the two headphones connect wirelessly), and I
>>>  have multiple WiFi networks available (one access point in the same room as
>>>  the Bluetooth transmitter, a few others behind walls). I expect 2.4 GHz
>>>  radio to be rather crowded. The gamepad and the headphones are in the same
>>>  room as the Bluetooth transmitter, in clear direct visibility, so it can't
>>>  get better than that.
>>  Yes, 2.4 GHz is shared by both Bluetooth and WiFi, so it may be a
>>  problem.
>>>  I can see Pali's patches offer reduce_encoder_bitrate API that is supposed
>>>  to mitigate this problem, but both SBC XQ profiles don't allow bitrate
>>>  reduction.
>>  Yes, SBC XQ is there the highest available quality profile of SBC.
>>>  I think, SBC XQ desperately needs to support bitrate reduction,
>>  No, this is main reason for usage of SBC XQ it is high quality codec.
>>  SBC XQ needs high bitrate by its definition.
>>>  as the codec with the highest bitrate out of all. Users might actually have
>>>  reduced experience due to audio dropouts compared to the previously
>>>  supported SBC HQ.
>>  If you cannot use high bitrate codecs, then do not use high bitrate
>>  codecs. There are other profiles of SBC which lower bitpool value and
>>  therefore lower bitrate. E.g. SBC MQ or SBC LQ (medium and low quality).
>>  Or you can use SBC in automatic mode where bitrate is automatically
>>  decreased.
> As a user, I don't know whether I can use SBC XQ. I don't know whether
> its bitrate will fit in my radio conditions. If my device happens to
> support SBC XQ, that is the codec that will get picked upon connection.
> Please, correct me if I'm wrong, but I don't see a way to influence that.
> SBC XQ is high quality and high bitrate, true, but PA should adapt to
> the actual use conditions. More so if it actually has the means to do
> so. If PA detects that SBC XQ does not fit in BT bandwidth, it should
> gradually drop quality.

Please take a look at the many discussions, experiments, specifications analysis and calculations about 
SBC XQ, before posting this kind of complaint. You make devs waste a lot of time at this point of implementation.

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