Dne 04. 10. 21 v 11:24 Jaroslav Kysela napsal(a):

On 01. 10. 21 10:35, Pavel Hofman wrote:

...

Hi,

I added support for "Playback Pitch 1000000" ctl elem to UAC2 gadget (not submitted to USB yet) and now I am working on alsaloop support for this ctl elem. The changes are simple (tested to work perfectly, patch to follow), but during the work I hit the following issue with playback Loopback "PCM Rate Shift 100000".

If the snd-aloop device is on playback side (i.e. capture from soundcard -> Loopback), the required sync mode is PLAYSHIFT. That means Loopback ctl elem "PCM Rate Shift 100000" should be controlled (by a reciprocal). That is simple by a patch like this:

diff --git a/alsaloop/pcmjob.c b/alsaloop/pcmjob.c index 845ab82..619bf35 100644 --- a/alsaloop/pcmjob.c +++ b/alsaloop/pcmjob.c @@ -1061,7 +1061,13 @@ static int set_rate_shift(struct loopback_handle *lhandle, double pitch)           int err;

if (lhandle->ctl_rate_shift) { -               snd_ctl_elem_value_set_integer(lhandle->ctl_rate_shift, 0, pitch * 100000); +               long value; +               if (lhandle->loopback->play == lhandle) +                       // playback => reciprocal +                       value = 1/(pitch) * 100000; +               else +                       value = pitch * 100000; +               snd_ctl_elem_value_set_integer(lhandle->ctl_rate_shift, 0, value);                   err = snd_ctl_elem_write(lhandle->ctl, lhandle->ctl_rate_shift);           } else if (lhandle->capt_pitch) {                   snd_ctl_elem_value_set_integer(lhandle->capt_pitch, 0, (1 / pitch) * 1000000); @@ -1205,15 +1211,18 @@ static int openctl(struct loopback_handle *lhandle, int device, int subdevice)           int err;

lhandle->ctl_rate_shift = NULL; +       // both play and capture +       openctl_elem(lhandle, device, subdevice, "PCM Notify", +                       &lhandle->ctl_notify); +       openctl_elem(lhandle, device, subdevice, "PCM Rate Shift 100000", +                       &lhandle->ctl_rate_shift);           if (lhandle->loopback->play == lhandle) { +               // play only                   if (lhandle->loopback->controls)                           goto __events;                   return 0;           } -       openctl_elem(lhandle, device, subdevice, "PCM Notify", -                       &lhandle->ctl_notify); -       openctl_elem(lhandle, device, subdevice, "PCM Rate Shift 100000", -                       &lhandle->ctl_rate_shift); +       // capture only           openctl_elem(lhandle, device, subdevice, "Capture Pitch 1000000",                           &lhandle->capt_pitch);           set_rate_shift(lhandle, 1);

However, IIUC how the Loopback device works, the "PCM Rate Shift 100000" ctl elem applicable to device=0 on playback side is that of the capture side, i.e. for device=1. The patch above would pick the playback-side device=0 ctl elem in pcmjob.c:openctl_elem. Hard-coding the device=0 -> device=1 is possible, but Loopback supports more devices.

Please what solution for picking the correct "PCM Rate Shift 100000" ctl elem for the PLAYSHIFT sync mode would you recommend?

Hi,

I would not touch the controls associated to the capture PCM by default. It would be possible to add another alsaloop option and code to configure the rate shift control identifier separately for this use case. The user should avoid the double pitch control (playback + capture) for the loopback devices.

Thanks for your input. I am not sure I understand correctly your intention.

The current code already avoids running playback and capture pitch control concurrently by one alsaloop as the loop->sync is either SYNC_TYPE_CAPTRATESHIFT or SYNC_TYPE_PLAYRATESHIFT. IMO the current code ignores SYNC_TYPE_PLAYRATESHIFT because the code jumps to set_rate_shift(loop->play, pitch) https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L11... but the lhandle->ctl_rate_shift elem is never set for playback side in pcmjob.c:openctl https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L12... (lhandle->loopback->play == lhandle). I confirmed it using the debug patch you accepted today (thanks! :-)).

Therefore my patch of the openctl moves the "PCM Notify" and "PCM Rate Shift 100000" setup before the playback check, so that lhandles of both directions can have the two elems configured.

But the loopback->play lhandle should configure elements for the capture side of the snd-aloop pipe which I do not know how to locate nicely. I can always use some hack "if device==0 then use device = 1" for the playback side etc. but that does not look nice.

Thanks a lot,

Pavel.

Dne 04. 10. 21 v 13:55 Jaroslav Kysela napsal(a):

...

...

Hi,

I would not touch the controls associated to the capture PCM by default. It would be possible to add another alsaloop option and code to configure the rate shift control identifier separately for this use case. The user should avoid the double pitch control (playback + capture) for the loopback devices.

Thanks for your input. I am not sure I understand correctly your intention.

The current code already avoids running playback and capture pitch control concurrently by one alsaloop as the loop->sync is either SYNC_TYPE_CAPTRATESHIFT or SYNC_TYPE_PLAYRATESHIFT. IMO the current code ignores SYNC_TYPE_PLAYRATESHIFT because the code jumps to set_rate_shift(loop->play, pitch) https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L11...

but the lhandle->ctl_rate_shift elem is never set for playback side in pcmjob.c:openctl https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L12...

(lhandle->loopback->play == lhandle). I confirmed it using the debug patch you accepted today (thanks! :-)).

Therefore my patch of the openctl moves the "PCM Notify" and "PCM Rate Shift 100000" setup before the playback check, so that lhandles of both directions can have the two elems configured.

But the loopback->play lhandle should configure elements for the capture side of the snd-aloop pipe which I do not know how to locate nicely. I can always use some hack "if device==0 then use device = 1" for the playback side etc. but that does not look nice.

Please, assume that the 'PCM Rate Shift 100000' control is for the capture PCM only by default. The applications should not handle those driver specific mapping.

If the user wants to use this control for the playback side, a new command line option may be added to cope with the alternate playback rate shift control indentifier (it may be parsed using snd_ctl_ascii_elem_id_parse() for example). So the user may specify the correct (different) device number there.

Thanks, please can you comment on this patch? alsaloop.1 not updated yet. Tested to work OK, while checking via amixer that the elem 'PCM Rate Shift 100000',device=1 gets controlled:

pavel@precision:~/work/rpi-gadget/alsa-utils/alsaloop$ ./alsaloop -vv -l 10000 v -c 2 -r 48000 -f S32_LE -C hw:Quartet -P hw:Loopback -S playshift -x iface=PCM,name='PCM Rate Shift 100000',device=1

!!!Scheduler set to Round Robin with priority 99 FAILED! Opened PCM element 'iface=PCM,name=PCM Rate Shift 100000,device=1' for playback rate adjust of hw:10 Hardware PCM card 10 'Loopback' device 0 subdevice 0 Its setup is: stream : PLAYBACK access : RW_INTERLEAVED format : S32_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 32 buffer_size : 39992 period_size : 4999 period_time : 104145 tstamp_mode : NONE tstamp_type : MONOTONIC period_step : 1 avail_min : 32494 period_event : 0 start_threshold : 2147483647 stop_threshold : 39992 silence_threshold: 0 silence_size : 0 boundary : 5628373634306277376 appl_ptr : 0 hw_ptr : 0 Hardware PCM card 0 'Infrasonic Quartet' device 0 subdevice 0 Its setup is: stream : CAPTURE access : RW_INTERLEAVED format : S32_LE subformat : STD channels : 2 rate : 48000 exact rate : 48000 (48000/1) msbits : 24 buffer_size : 32768 period_size : 4096 period_time : 85333 tstamp_mode : NONE tstamp_type : MONOTONIC period_step : 1 avail_min : 4096 period_event : 0 start_threshold : 2147483647 stop_threshold : 32768 silence_threshold: 0 silence_size : 0 boundary : 4611686018427387904 appl_ptr : 0 hw_ptr : 0 Latency 9999 frames, 208312.500us, 208.312500ms (4.8005Hz) shared buffer!!! playback hw:Loopback/capture hw:Quartet sync type: PLAYRATESHIFT New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = 0/0) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = 0/35) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = 0/35) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = 0/35) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = 0/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = 0/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = 0/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = -14/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = -29/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00003125 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = -32/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = -38/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = -41/39) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = -41/39)

Without specifying the -x CONTROL_NAME param (no rate control applied) the pitch starts diverging:

New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000 (min/max samples = 0/0) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042 (min/max samples = 0/14) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083 (min/max samples = 0/16) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00003125 (min/max samples = 0/17) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00004167 (min/max samples = 0/21) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00005208 (min/max samples = 0/23) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00006250 (min/max samples = 0/27) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00007292 (min/max samples = 0/29) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00008333 (min/max samples = 0/33) New pitch for playback hw:Loopback/capture hw:Quartet: 1.00009375 (min/max samples = 0/34)

Thanks a lot,

Pavel.

============================================================= diff --git a/alsaloop/alsaloop.c b/alsaloop/alsaloop.c index 06ffadf..4358db0 100644 --- a/alsaloop/alsaloop.c +++ b/alsaloop/alsaloop.c @@ -175,6 +175,7 @@ void help(void) "-C,--cdevice capture device\n" "-X,--pctl playback ctl device\n" "-Y,--cctl capture ctl device\n" +"-x,--prateshift playback 'PCM Rate Shift 100000' ascii ctl name\n" "-l,--latency requested latency in frames\n" "-t,--tlatency requested latency in usec (1/1000000sec)\n" "-f,--format sample format\n" @@ -362,6 +363,7 @@ static int parse_config(int argc, char *argv[], snd_output_t *output, {"cdevice", 1, NULL, 'C'}, {"pctl", 1, NULL, 'X'}, {"cctl", 1, NULL, 'Y'}, + {"prateshift", 1, NULL, 'x'}, {"latency", 1, NULL, 'l'}, {"tlatency", 1, NULL, 't'}, {"format", 1, NULL, 'f'}, @@ -391,6 +393,7 @@ static int parse_config(int argc, char *argv[], snd_output_t *output, char *arg_cdevice = NULL; char *arg_pctl = NULL; char *arg_cctl = NULL; + char *arg_prateshift = NULL; unsigned int arg_latency_req = 0; unsigned int arg_latency_reqtime = 10000; snd_pcm_format_t arg_format = SND_PCM_FORMAT_S16_LE; @@ -420,7 +423,7 @@ static int parse_config(int argc, char *argv[], snd_output_t *output, while (1) { int c; if ((c = getopt_long(argc, argv, - "hdg:P:C:X:Y:l:t:F:f:c:r:s:benvA:S:a:m:T:O:w:UW:z", + "hdg:P:C:X:Y:x:l:t:F:f:c:r:s:benvA:S:a:m:T:O:w:UW:z", long_option, NULL)) < 0) break; switch (c) { @@ -446,6 +449,9 @@ static int parse_config(int argc, char *argv[], snd_output_t *output, case 'Y': arg_cctl = strdup(optarg); break; + case 'x': + arg_prateshift = strdup(optarg); + break; case 'l': err = atoi(optarg); arg_latency_req = err >= 4 ? err : 4; @@ -627,6 +633,10 @@ static int parse_config(int argc, char *argv[], snd_output_t *output, logit(LOG_CRIT, "Unable to add ossmixer controls.\n"); exit(EXIT_FAILURE); } + if (arg_prateshift) { + play->prateshift_name = arg_prateshift; + } + #ifdef USE_SAMPLERATE loop->src_enable = arg_samplerate > 0; if (loop->src_enable) diff --git a/alsaloop/alsaloop.h b/alsaloop/alsaloop.h index 1dbcefe..7a98ef3 100644 --- a/alsaloop/alsaloop.h +++ b/alsaloop/alsaloop.h @@ -127,6 +127,7 @@ struct loopback_handle { snd_ctl_elem_value_t *ctl_format; snd_ctl_elem_value_t *ctl_rate; snd_ctl_elem_value_t *ctl_channels; + char *prateshift_name; /* ascii name for the playback rate shift ctl elem */ };

struct loopback { diff --git a/alsaloop/pcmjob.c b/alsaloop/pcmjob.c index 845ab82..a4b28e3 100644 --- a/alsaloop/pcmjob.c +++ b/alsaloop/pcmjob.c @@ -1101,7 +1101,8 @@ void update_pitch(struct loopback *loop) #endif } else if (loop->sync == SYNC_TYPE_PLAYRATESHIFT) { - set_rate_shift(loop->play, pitch); + // pitch is capture-based, playback side requires reciprocal + set_rate_shift(loop->play, 1 / pitch); #ifdef USE_SAMPLERATE if (loop->use_samplerate) { loop->src_data.src_ratio = @@ -1200,16 +1201,66 @@ static void openctl_elem(struct loopback_handle *lhandle, } }

+static int openctl_play_rateshift(struct loopback_handle *lhandle, + char *ascii_name) { + int err; + snd_ctl_elem_id_t *id; + snd_ctl_elem_value_t **elem; + + elem = &lhandle->ctl_rate_shift; + + if (snd_ctl_elem_value_malloc(elem) < 0) { + return -ENOMEM; + } + + if (snd_ctl_elem_id_malloc(&id)) { + snd_ctl_elem_value_free(*elem); + return -ENOMEM; + } + + if (snd_ctl_ascii_elem_id_parse(id, ascii_name)) { + snd_ctl_elem_id_free(id); + snd_ctl_elem_value_free(*elem); + fprintf(stderr, "Wrong control identifier: %s\n", ascii_name); + return -EINVAL; + } + + snd_ctl_elem_value_set_id(*elem, id); + err = snd_ctl_elem_read(lhandle->ctl, *elem); + if (err < 0) { + snd_ctl_elem_id_free(id); + snd_ctl_elem_value_free(*elem); + return err; + } else { + snd_output_printf(lhandle->loopback->output, + "Opened PCM element '%s' for playback rate adjust of %s\n", + ascii_name, snd_ctl_name(lhandle->ctl)); + } + return 0; +} + + static int openctl(struct loopback_handle *lhandle, int device, int subdevice) { int err;

- lhandle->ctl_rate_shift = NULL; if (lhandle->loopback->play == lhandle) { + // play only + if (lhandle->prateshift_name) { + err = openctl_play_rateshift(lhandle, lhandle->prateshift_name); + if (err < 0) { + logit(LOG_CRIT, "Unable to open playback PCM Rate Shift elem '%s'.\n", + lhandle->prateshift_name); + exit(EXIT_FAILURE); + } + } + if (lhandle->loopback->controls) goto __events; return 0; } + // capture only + lhandle->ctl_rate_shift = NULL; openctl_elem(lhandle, device, subdevice, "PCM Notify", &lhandle->ctl_notify); openctl_elem(lhandle, device, subdevice, "PCM Rate Shift 100000",