i.MX Processors中的主题 ASRC conversion fails for some rates

ASRC conversion fails for some rates

scrapper — Wed, 20 May 2015 19:49:03 GMT

I am using the ASRC in the imx6q, together with SSI based ALSA sound cards. When I configure the SSI ports to operate at a native sampling rate of 96KHz, then I can play back audio files with a sampling rate ranging from 44.1KHz up to 192 KHz. But when I configure the SSI ports to use a native sampling rate of 44.1 KHz, then the ASRC only works up to 88.2 KHz. When I configure the SSI ports to use a native sampling rate of 48 KHz, then the ASRC only works up to 96 KHz. When I try to play back higher sampling rate audio files, there is basically no audio and I am getting timeouts "conversion failed" error messages from the fsl-alsa-plugins library.

While everything is working fine for 96 KHz, I still want to set the SSI native sampling rate to 44.1 KHz, mainly because the overwhelming majority of content is still available at this rate. What could be the problem that cause the conversion errors?

Re: ASRC conversion fails for some rates

jimmychan — Mon, 01 Jun 2015 04:20:19 GMT

could you tell me which bsp are you using? which part of code you modified?

Re: ASRC conversion fails for some rates

scrapper — Thu, 04 Jun 2015 18:31:53 GMT

I am using the yocto linux daisy branch with linux kernel version 3.10.53 (tag: imx_3.10.53_1.1.0_ga)

I have added a new SSI based sound card driver to this kernel, no other modifications. To the yocto distribution, I have added the fsl-alsa-plugins and defined aliases in /etc/asound.conf for the asrc. Here is the asound.conf:

defaults.pcm.rate_converter "asrcrate"

pcm.sc0 {

type hw

card 0

device 0

}

pcm.sc1 {

type hw

card 1

device 0

}

pcm.sc2 {

type hw

card 2

device 0

}

pcm.sc3 {

type hw

card 3

device 0

}

pcm.asrc0 {

type plug

slave {

pcm "sc0"

format S24_LE

channels 2

rate 96000

}

pcm.asrc1 {

type plug

slave {

pcm "sc1"

format S24_LE

channels 2

rate 96000

}

pcm.asrc2 {

type plug

slave {

pcm "sc2"

format S24_LE

channels 2

rate 44100

}

pcm.asrc3 {

type plug

slave {

pcm "sc3"

format S24_LE

channels 2

rate 48000

}

pcm.sv_sc0 {

type softvol

slave {

pcm "sc0"

}

control {

name "Master"

card 0

}

pcm.sv_sc1 {

type softvol

slave {

pcm "sc1"

}

control {

name "Master"

card 1

}

pcm.sv_sc3 {

type softvol

slave {

pcm "sc3"

}

control {

name "Master"

card 3

}

pcm.sv_asrc0 {

type softvol

slave {

pcm "asrc0"

}

control {

name "Master"

card 0

}

pcm.sv_asrc1 {

type softvol

slave {

pcm "asrc1"

}

control {

name "Master"

card 1

}

pcm.sv_asrc3 {

type softvol

slave {

pcm "asrc3"

}

control {

name "Master"

card 3

}