[alsa-devel] Line6 Helix - usb compliant but not working correct
Jens Verwiebe
info at jensverwiebe.de
Wed Nov 29 16:24:10 CET 2017
Hi,, yeah thx for looking into it.
TBH i tried all kinda stuff already and also am able to compare all logs
with a Focusrite Scarlett 6i6, which shows
almost exactly same outputs but works just fine. This makes me clueless.
I also investigated if this could be a firmware bug, but then it would
not work on osx either, no ?
Something new i found: if i capture from helix and play this file with
scarlett all is fine. So it seems to be something
with out-of-sync playback only.
Am 29.11.2017 um 15:51 schrieb Jorge:
>
>
> On 29/11/17 13:26, Jens Verwiebe wrote:
>> Hi folks
>>
>> I recently got a Line6 Helix LT which can work usb compliant for
>> example on
>
> Interesting. I would like to try the Helix in Linux too. I have seen
> similar issues when fiddling with
> set_sample_rate. Some comments/ideas below.
>
>>
>> OSX or IOS. No driver is needed but the samplerate is fixed to 48000
>> ( which is okay for the first ).
>>
>> Now i expected this device to work ootb in alsa, which turned out to
>> be half the truth.
>>
>> Connecting the device threw " usb 7-2: parse_audio_format_rates_v2():
>> unable to retrieve number of sample rates (clock 16)"
>>
>> so i investigated a bit and found this workaround:
>>
>> ---
>> "/media/Workdata3/Development/kernel_lowlat_4.4-97/linux-4.4.97/sound/usb/clock
>> (Kopie).c" 2017-11-08 10:06:31.000000000 +0100
>> +++
>> /media/Workdata3/Development/kernel_lowlat_4.4-97/linux-4.4.97/sound/usb/clock.c
>> 2017-11-14 23:06:51.750924051 +0100
>> @@ -361,6 +361,13 @@ static int set_sample_rate_v2(struct snd
>> struct uac_clock_source_descriptor *cs_desc;
>>
>> clock = snd_usb_clock_find_source(chip, fmt->clock, true);
>> + /*
>> + * Line6 HELIX does not respond to sample rate
>> + * set requests. The only valid rate is 48000.
>> + */
>> + if (chip->usb_id == USB_ID(0x0e41, 0x4244) && rate == 48000)
>> + return 0;
>> +
>> if (clock < 0)
>> return clock;
>>
>> ---
>> "/media/Workdata3/Development/kernel_lowlat_4.4-97/linux-4.4.97/sound/usb/format
>> (Kopie).c" 2017-11-08 10:06:31.000000000 +0100
>> +++
>> /media/Workdata3/Development/kernel_lowlat_4.4-97/linux-4.4.97/sound/usb/format.c
>> 2017-11-14 23:12:24.329766243 +0100
>> @@ -293,6 +293,20 @@ static int parse_audio_format_rates_v2(s
>> int nr_triplets, data_size, ret = 0;
>> int clock = snd_usb_clock_find_source(chip, fp->clock, false);
>>
>> + /*
>> + * Line6 HELIX does not respond to sample rate
>> + * query requests. The only valid rate is 48000.
>> + */
>> + if (chip->usb_id == USB_ID(0x0e41, 0x4244)) {
>> + fp->nr_rates = 1;
>> + fp->rate_min = 48000;
>> + fp->rate_max = 48000;
>> + fp->rates = SNDRV_PCM_RATE_48000;
>> + fp->rate_table = kmalloc(sizeof(int), GFP_KERNEL);
>> + fp->rate_table[0] = 48000;
>> + return 0;
>> + }
>> +
>> if (clock < 0) {
>> dev_err(&dev->dev,
>> "%s(): unable to find clock source (clock %d)\n",
>>
>>
>> This trick made the device appear in aplay -l and /proc/asound just
>> as expected.
>>
>> [ 7988.495085] usb 7-2: new high-speed USB device number 4 using
>> xhci_hcd
>> [ 7988.663622] usb 7-2: New USB device found, idVendor=0e41,
>> idProduct=4244
>> [ 7988.663625] usb 7-2: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=3
>> [ 7988.663627] usb 7-2: Product: HELIX
>> [ 7988.663629] usb 7-2: Manufacturer: LINE 6
>> [ 7988.663630] usb 7-2: SerialNumber: 2744535
>>
>> But i ended up with sometimes occuring soft clicks in playback which
>> imply i have timing problems.
>>
>> Another symptom is aplay does not output any sound while not throwing
>> any error while in jack i can create the driver just fine.
>
> Have you tried debugging the pointer position with that device? Do you
> get sensible buffer sizes
> with `-v` in aplay for 48KHz, 24 bits, etc?
I get just this but silence ( while plughhw:1,0 == scarlett looks same
and plays sound ):
aplay -D plughw:6,0 -vv test.wav
Wiedergabe: WAVE 'test.wav' : Signed 16 bit Little Endian, Rate: 44100
Hz, stereo
Plug PCM: Rate conversion PCM (48000, sformat=S16_LE)
Converter: libspeex (builtin)
Protocol version: 10002
Its setup is:
stream : PLAYBACK
access : RW_INTERLEAVED
format : S16_LE
subformat : STD
channels : 2
rate : 44100
exact rate : 44100 (44100/1)
msbits : 16
buffer_size : 22050
period_size : 5512
period_time : 125000
tstamp_mode : NONE
period_step : 1
avail_min : 5512
period_event : 0
start_threshold : 22050
stop_threshold : 22050
silence_threshold: 0
silence_size : 0
boundary : 6206523236469964800
Slave: Route conversion PCM (sformat=S32_LE)
Transformation table:
0 <- 0
1 <- 1
2 <- none
3 <- none
4 <- none
5 <- none
6 <- none
7 <- none
Its setup is:
stream : PLAYBACK
access : MMAP_INTERLEAVED
format : S16_LE
subformat : STD
channels : 2
rate : 48000
exact rate : 48000 (48000/1)
msbits : 16
buffer_size : 24001
period_size : 6000
period_time : 125000
tstamp_mode : NONE
period_step : 1
avail_min : 6000
period_event : 0
start_threshold : 24000
stop_threshold : 24001
silence_threshold: 0
silence_size : 0
boundary : 6755680916032454656
Slave: Hardware PCM card 6 'HELIX' device 0 subdevice 0
Its setup is:
stream : PLAYBACK
access : MMAP_INTERLEAVED
format : S32_LE
subformat : STD
channels : 8
rate : 48000
exact rate : 48000 (48000/1)
msbits : 32
buffer_size : 24001
period_size : 6000
period_time : 125000
tstamp_mode : NONE
period_step : 1
avail_min : 6000
period_event : 0
start_threshold : 24000
stop_threshold : 24001
silence_threshold: 0
silence_size : 0
boundary : 6755680916032454656
appl_ptr : 0
hw_ptr : 0
>
> I once ended up with really small buffers when I changed the usb
> audioformats for a fixed rate device
> so there was not sound whatsoever even though all the devices were
> present. I am not sure whether
> fp->rates should get SNDRV_PCM_RATE_CONTINUOUS either way and then
> min/max = 48KHz delimiting it.
Tried this already, makes no difference.
>
> Jorge.
>
>>
>> I would apreciate any hint what i could try out here.
>>
>>
>> Greetings from Hamburg ... Jens
>>
>
>
My wisdom is at the end here ... Jens ;-)
--
Jens Verwiebe
Allerskehre 44 - 22309 Hamburg
Tel.: +49 40 68 78 50
mobile: +49 172 400 49 07
mailto: info at jensverwiebe.de
web: http://www.jensverwiebe.de
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