On Sunday 22 July 2018 13:37:06 Pali Rohár wrote: > On Sunday 22 July 2018 11:52:11 Georgi Boiko wrote: > > For codecs focusing on latency over sound quality, if I absolutely had to > > support them, I would put AptX LL between AptX and AAC. FastStream seems to > > be even more niche and focused purely on voice over HiFi audio on just a > > Information which I have about FastStream: It is just SBC codec with > following parameters: frequency rate 44.1 kHz or 48.0 kHz, Blocks 16, > Sub-bands 8, Joint Stereo, Loudness and Bitpool = 29. So data rate = 212 > kbps, packet size = 72*3+4 = 220 = DM5 and that DSP decoders round 71 > bytes frames to 72 bytes. So I'm not sure how "low latency" it is. > Normal SBC codec allows you to specify all those parameters. But > FastStream has one additional feature: it supports backchannel for > voice, so you do not have to switch between HFP/HSP and A2DP once you > have incoming voice call. You can always use just A2DP with FastStream. And information about aptX Low Latency codec: It is just normal aptX with different A2DP parameters and support for some kind of backchannel. Therefore existing aptX (non HD) encoder and decoder (like proprietary Android's, ffmpeg or https://github.com/pali/libopenaptx) are enough for implementing aptX Low Latency A2DP support. A2DP structures for aptX Low Latency codec are already described in my patch, search for a2dp_aptx_ll_t. https://patchwork.freedesktop.org/patch/241444/ -- Pali Rohár pali.rohar@xxxxxxxxx
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