* zero appl_ptr reported
@ 2009-02-19 5:20 Wu Fengguang
2009-02-19 6:42 ` Takashi Iwai
0 siblings, 1 reply; 3+ messages in thread
From: Wu Fengguang @ 2009-02-19 5:20 UTC (permalink / raw)
To: Takashi Iwai; +Cc: alsa-devel
Hi Takashi,
I noticed that 'appl_ptr' is always 0 during playback, whether it be
mplayer or aplay, T61 or DG45ID. Is this a bug?
% grep -r . /proc/asound/card0/pcm0p
/proc/asound/card0/pcm0p/sub0/prealloc_max:32768
/proc/asound/card0/pcm0p/sub0/prealloc:64
/proc/asound/card0/pcm0p/sub0/status:state: RUNNING
/proc/asound/card0/pcm0p/sub0/status:trigger_time: 260.550520867
/proc/asound/card0/pcm0p/sub0/status:tstamp : 264.361429403
/proc/asound/card0/pcm0p/sub0/status:delay : -182952
/proc/asound/card0/pcm0p/sub0/status:avail : 191144
/proc/asound/card0/pcm0p/sub0/status:avail_max : 191144
/proc/asound/card0/pcm0p/sub0/status:-----
/proc/asound/card0/pcm0p/sub0/status:hw_ptr : 182952
/proc/asound/card0/pcm0p/sub0/status:appl_ptr : 0
/proc/asound/card0/pcm0p/sub0/sw_params:tstamp_mode: ENABLE
/proc/asound/card0/pcm0p/sub0/sw_params:period_step: 1
/proc/asound/card0/pcm0p/sub0/sw_params:avail_min: 1024
/proc/asound/card0/pcm0p/sub0/sw_params:start_threshold: 1
/proc/asound/card0/pcm0p/sub0/sw_params:stop_threshold: 4611686018427387904
/proc/asound/card0/pcm0p/sub0/sw_params:silence_threshold: 0
/proc/asound/card0/pcm0p/sub0/sw_params:silence_size: 4611686018427387904
/proc/asound/card0/pcm0p/sub0/sw_params:boundary: 4611686018427387904
/proc/asound/card0/pcm0p/sub0/hw_params:access: MMAP_INTERLEAVED
/proc/asound/card0/pcm0p/sub0/hw_params:format: S32_LE
/proc/asound/card0/pcm0p/sub0/hw_params:subformat: STD
/proc/asound/card0/pcm0p/sub0/hw_params:channels: 2
/proc/asound/card0/pcm0p/sub0/hw_params:rate: 48000 (48000/1)
/proc/asound/card0/pcm0p/sub0/hw_params:period_size: 1024
/proc/asound/card0/pcm0p/sub0/hw_params:buffer_size: 8192
/proc/asound/card0/pcm0p/sub0/info:card: 0
/proc/asound/card0/pcm0p/sub0/info:device: 0
/proc/asound/card0/pcm0p/sub0/info:subdevice: 0
/proc/asound/card0/pcm0p/sub0/info:stream: PLAYBACK
/proc/asound/card0/pcm0p/sub0/info:id: STAC92xx Analog
/proc/asound/card0/pcm0p/sub0/info:name: STAC92xx Analog
/proc/asound/card0/pcm0p/sub0/info:subname: subdevice #0
/proc/asound/card0/pcm0p/sub0/info:class: 0
/proc/asound/card0/pcm0p/sub0/info:subclass: 0
/proc/asound/card0/pcm0p/sub0/info:subdevices_count: 1
/proc/asound/card0/pcm0p/sub0/info:subdevices_avail: 0
/proc/asound/card0/pcm0p/xrun_debug:0
/proc/asound/card0/pcm0p/info:card: 0
/proc/asound/card0/pcm0p/info:device: 0
/proc/asound/card0/pcm0p/info:subdevice: 0
/proc/asound/card0/pcm0p/info:stream: PLAYBACK
/proc/asound/card0/pcm0p/info:id: STAC92xx Analog
/proc/asound/card0/pcm0p/info:name: STAC92xx Analog
/proc/asound/card0/pcm0p/info:subname: subdevice #0
/proc/asound/card0/pcm0p/info:class: 0
/proc/asound/card0/pcm0p/info:subclass: 0
/proc/asound/card0/pcm0p/info:subdevices_count: 1
/proc/asound/card0/pcm0p/info:subdevices_avail: 0
Interestingly DG45ID HDMI audio playback does not have this problem:
/proc/asound/card0/pcm3p/sub0/prealloc_max:32768
/proc/asound/card0/pcm3p/sub0/prealloc:64
/proc/asound/card0/pcm3p/sub0/status:state: RUNNING
/proc/asound/card0/pcm3p/sub0/status:trigger_time: 441.375970806
/proc/asound/card0/pcm3p/sub0/status:tstamp : 447.039903859
/proc/asound/card0/pcm3p/sub0/status:delay : 16096
/proc/asound/card0/pcm3p/sub0/status:avail : 288
/proc/asound/card0/pcm3p/sub0/status:avail_max : 288
/proc/asound/card0/pcm3p/sub0/status:-----
/proc/asound/card0/pcm3p/sub0/status:hw_ptr : 249824
/proc/asound/card0/pcm3p/sub0/status:appl_ptr : 265920
/proc/asound/card0/pcm3p/sub0/sw_params:tstamp_mode: NONE
/proc/asound/card0/pcm3p/sub0/sw_params:period_step: 1
/proc/asound/card0/pcm3p/sub0/sw_params:avail_min: 1024
/proc/asound/card0/pcm3p/sub0/sw_params:start_threshold: 1024
/proc/asound/card0/pcm3p/sub0/sw_params:stop_threshold: 4611686018427387904
/proc/asound/card0/pcm3p/sub0/sw_params:silence_threshold: 0
/proc/asound/card0/pcm3p/sub0/sw_params:silence_size: 4611686018427387904
/proc/asound/card0/pcm3p/sub0/sw_params:boundary: 4611686018427387904
/proc/asound/card0/pcm3p/sub0/hw_params:access: RW_INTERLEAVED
/proc/asound/card0/pcm3p/sub0/hw_params:format: S16_LE
/proc/asound/card0/pcm3p/sub0/hw_params:subformat: STD
/proc/asound/card0/pcm3p/sub0/hw_params:channels: 2
/proc/asound/card0/pcm3p/sub0/hw_params:rate: 44100 (44100/1)
/proc/asound/card0/pcm3p/sub0/hw_params:period_size: 1024
/proc/asound/card0/pcm3p/sub0/hw_params:buffer_size: 16384
/proc/asound/card0/pcm3p/sub0/info:card: 0
/proc/asound/card0/pcm3p/sub0/info:device: 3
/proc/asound/card0/pcm3p/sub0/info:subdevice: 0
/proc/asound/card0/pcm3p/sub0/info:stream: PLAYBACK
/proc/asound/card0/pcm3p/sub0/info:id: INTEL HDMI
/proc/asound/card0/pcm3p/sub0/info:name: INTEL HDMI
/proc/asound/card0/pcm3p/sub0/info:subname: subdevice #0
/proc/asound/card0/pcm3p/sub0/info:class: 0
/proc/asound/card0/pcm3p/sub0/info:subclass: 0
/proc/asound/card0/pcm3p/sub0/info:subdevices_count: 1
/proc/asound/card0/pcm3p/sub0/info:subdevices_avail: 0
/proc/asound/card0/pcm3p/xrun_debug:0
/proc/asound/card0/pcm3p/info:card: 0
/proc/asound/card0/pcm3p/info:device: 3
/proc/asound/card0/pcm3p/info:subdevice: 0
/proc/asound/card0/pcm3p/info:stream: PLAYBACK
/proc/asound/card0/pcm3p/info:id: INTEL HDMI
/proc/asound/card0/pcm3p/info:name: INTEL HDMI
/proc/asound/card0/pcm3p/info:subname: subdevice #0
/proc/asound/card0/pcm3p/info:class: 0
/proc/asound/card0/pcm3p/info:subclass: 0
/proc/asound/card0/pcm3p/info:subdevices_count: 1
/proc/asound/card0/pcm3p/info:subdevices_avail: 0
Thanks,
Fengguang
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: zero appl_ptr reported
2009-02-19 5:20 zero appl_ptr reported Wu Fengguang
@ 2009-02-19 6:42 ` Takashi Iwai
2009-02-20 13:29 ` Wu Fengguang
0 siblings, 1 reply; 3+ messages in thread
From: Takashi Iwai @ 2009-02-19 6:42 UTC (permalink / raw)
To: Wu Fengguang; +Cc: alsa-devel
At Thu, 19 Feb 2009 13:20:16 +0800,
Wu Fengguang wrote:
>
> Hi Takashi,
>
> I noticed that 'appl_ptr' is always 0 during playback, whether it be
> mplayer or aplay, T61 or DG45ID. Is this a bug?
No, it's a feature. When you use dmix, the appl_ptr isn't updated
in the driver side but the driver is running in a "free-wheel" mode.
OTOH, if you use pulseaudio or use HDMI out, the device is opened in a
normal mode, thus appl_ptr is handled in the driver side.
Takashi
>
> % grep -r . /proc/asound/card0/pcm0p
> /proc/asound/card0/pcm0p/sub0/prealloc_max:32768
> /proc/asound/card0/pcm0p/sub0/prealloc:64
> /proc/asound/card0/pcm0p/sub0/status:state: RUNNING
> /proc/asound/card0/pcm0p/sub0/status:trigger_time: 260.550520867
> /proc/asound/card0/pcm0p/sub0/status:tstamp : 264.361429403
> /proc/asound/card0/pcm0p/sub0/status:delay : -182952
> /proc/asound/card0/pcm0p/sub0/status:avail : 191144
> /proc/asound/card0/pcm0p/sub0/status:avail_max : 191144
> /proc/asound/card0/pcm0p/sub0/status:-----
> /proc/asound/card0/pcm0p/sub0/status:hw_ptr : 182952
> /proc/asound/card0/pcm0p/sub0/status:appl_ptr : 0
> /proc/asound/card0/pcm0p/sub0/sw_params:tstamp_mode: ENABLE
> /proc/asound/card0/pcm0p/sub0/sw_params:period_step: 1
> /proc/asound/card0/pcm0p/sub0/sw_params:avail_min: 1024
> /proc/asound/card0/pcm0p/sub0/sw_params:start_threshold: 1
> /proc/asound/card0/pcm0p/sub0/sw_params:stop_threshold: 4611686018427387904
> /proc/asound/card0/pcm0p/sub0/sw_params:silence_threshold: 0
> /proc/asound/card0/pcm0p/sub0/sw_params:silence_size: 4611686018427387904
> /proc/asound/card0/pcm0p/sub0/sw_params:boundary: 4611686018427387904
> /proc/asound/card0/pcm0p/sub0/hw_params:access: MMAP_INTERLEAVED
> /proc/asound/card0/pcm0p/sub0/hw_params:format: S32_LE
> /proc/asound/card0/pcm0p/sub0/hw_params:subformat: STD
> /proc/asound/card0/pcm0p/sub0/hw_params:channels: 2
> /proc/asound/card0/pcm0p/sub0/hw_params:rate: 48000 (48000/1)
> /proc/asound/card0/pcm0p/sub0/hw_params:period_size: 1024
> /proc/asound/card0/pcm0p/sub0/hw_params:buffer_size: 8192
> /proc/asound/card0/pcm0p/sub0/info:card: 0
> /proc/asound/card0/pcm0p/sub0/info:device: 0
> /proc/asound/card0/pcm0p/sub0/info:subdevice: 0
> /proc/asound/card0/pcm0p/sub0/info:stream: PLAYBACK
> /proc/asound/card0/pcm0p/sub0/info:id: STAC92xx Analog
> /proc/asound/card0/pcm0p/sub0/info:name: STAC92xx Analog
> /proc/asound/card0/pcm0p/sub0/info:subname: subdevice #0
> /proc/asound/card0/pcm0p/sub0/info:class: 0
> /proc/asound/card0/pcm0p/sub0/info:subclass: 0
> /proc/asound/card0/pcm0p/sub0/info:subdevices_count: 1
> /proc/asound/card0/pcm0p/sub0/info:subdevices_avail: 0
> /proc/asound/card0/pcm0p/xrun_debug:0
> /proc/asound/card0/pcm0p/info:card: 0
> /proc/asound/card0/pcm0p/info:device: 0
> /proc/asound/card0/pcm0p/info:subdevice: 0
> /proc/asound/card0/pcm0p/info:stream: PLAYBACK
> /proc/asound/card0/pcm0p/info:id: STAC92xx Analog
> /proc/asound/card0/pcm0p/info:name: STAC92xx Analog
> /proc/asound/card0/pcm0p/info:subname: subdevice #0
> /proc/asound/card0/pcm0p/info:class: 0
> /proc/asound/card0/pcm0p/info:subclass: 0
> /proc/asound/card0/pcm0p/info:subdevices_count: 1
> /proc/asound/card0/pcm0p/info:subdevices_avail: 0
>
>
> Interestingly DG45ID HDMI audio playback does not have this problem:
>
> /proc/asound/card0/pcm3p/sub0/prealloc_max:32768
> /proc/asound/card0/pcm3p/sub0/prealloc:64
> /proc/asound/card0/pcm3p/sub0/status:state: RUNNING
> /proc/asound/card0/pcm3p/sub0/status:trigger_time: 441.375970806
> /proc/asound/card0/pcm3p/sub0/status:tstamp : 447.039903859
> /proc/asound/card0/pcm3p/sub0/status:delay : 16096
> /proc/asound/card0/pcm3p/sub0/status:avail : 288
> /proc/asound/card0/pcm3p/sub0/status:avail_max : 288
> /proc/asound/card0/pcm3p/sub0/status:-----
> /proc/asound/card0/pcm3p/sub0/status:hw_ptr : 249824
> /proc/asound/card0/pcm3p/sub0/status:appl_ptr : 265920
> /proc/asound/card0/pcm3p/sub0/sw_params:tstamp_mode: NONE
> /proc/asound/card0/pcm3p/sub0/sw_params:period_step: 1
> /proc/asound/card0/pcm3p/sub0/sw_params:avail_min: 1024
> /proc/asound/card0/pcm3p/sub0/sw_params:start_threshold: 1024
> /proc/asound/card0/pcm3p/sub0/sw_params:stop_threshold: 4611686018427387904
> /proc/asound/card0/pcm3p/sub0/sw_params:silence_threshold: 0
> /proc/asound/card0/pcm3p/sub0/sw_params:silence_size: 4611686018427387904
> /proc/asound/card0/pcm3p/sub0/sw_params:boundary: 4611686018427387904
> /proc/asound/card0/pcm3p/sub0/hw_params:access: RW_INTERLEAVED
> /proc/asound/card0/pcm3p/sub0/hw_params:format: S16_LE
> /proc/asound/card0/pcm3p/sub0/hw_params:subformat: STD
> /proc/asound/card0/pcm3p/sub0/hw_params:channels: 2
> /proc/asound/card0/pcm3p/sub0/hw_params:rate: 44100 (44100/1)
> /proc/asound/card0/pcm3p/sub0/hw_params:period_size: 1024
> /proc/asound/card0/pcm3p/sub0/hw_params:buffer_size: 16384
> /proc/asound/card0/pcm3p/sub0/info:card: 0
> /proc/asound/card0/pcm3p/sub0/info:device: 3
> /proc/asound/card0/pcm3p/sub0/info:subdevice: 0
> /proc/asound/card0/pcm3p/sub0/info:stream: PLAYBACK
> /proc/asound/card0/pcm3p/sub0/info:id: INTEL HDMI
> /proc/asound/card0/pcm3p/sub0/info:name: INTEL HDMI
> /proc/asound/card0/pcm3p/sub0/info:subname: subdevice #0
> /proc/asound/card0/pcm3p/sub0/info:class: 0
> /proc/asound/card0/pcm3p/sub0/info:subclass: 0
> /proc/asound/card0/pcm3p/sub0/info:subdevices_count: 1
> /proc/asound/card0/pcm3p/sub0/info:subdevices_avail: 0
> /proc/asound/card0/pcm3p/xrun_debug:0
> /proc/asound/card0/pcm3p/info:card: 0
> /proc/asound/card0/pcm3p/info:device: 3
> /proc/asound/card0/pcm3p/info:subdevice: 0
> /proc/asound/card0/pcm3p/info:stream: PLAYBACK
> /proc/asound/card0/pcm3p/info:id: INTEL HDMI
> /proc/asound/card0/pcm3p/info:name: INTEL HDMI
> /proc/asound/card0/pcm3p/info:subname: subdevice #0
> /proc/asound/card0/pcm3p/info:class: 0
> /proc/asound/card0/pcm3p/info:subclass: 0
> /proc/asound/card0/pcm3p/info:subdevices_count: 1
> /proc/asound/card0/pcm3p/info:subdevices_avail: 0
>
> Thanks,
> Fengguang
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: zero appl_ptr reported
2009-02-19 6:42 ` Takashi Iwai
@ 2009-02-20 13:29 ` Wu Fengguang
0 siblings, 0 replies; 3+ messages in thread
From: Wu Fengguang @ 2009-02-20 13:29 UTC (permalink / raw)
To: Takashi Iwai; +Cc: alsa-devel@alsa-project.org
On Thu, Feb 19, 2009 at 08:42:15AM +0200, Takashi Iwai wrote:
> At Thu, 19 Feb 2009 13:20:16 +0800,
> Wu Fengguang wrote:
> >
> > Hi Takashi,
> >
> > I noticed that 'appl_ptr' is always 0 during playback, whether it be
> > mplayer or aplay, T61 or DG45ID. Is this a bug?
>
> No, it's a feature. When you use dmix, the appl_ptr isn't updated
> in the driver side but the driver is running in a "free-wheel" mode.
> OTOH, if you use pulseaudio or use HDMI out, the device is opened in a
> normal mode, thus appl_ptr is handled in the driver side.
Ah thanks. This dismissed my questions :)
The dmix plugin always returns error code or negative delay:
alsa-lib/src/pcm/pcm_dmix.c
477 static int snd_pcm_dmix_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
478 {
479 snd_pcm_direct_t *dmix = pcm->private_data;
480 int err;
481
482 switch(dmix->state) {
483 case SNDRV_PCM_STATE_DRAINING:
484 case SNDRV_PCM_STATE_RUNNING:
485 err = snd_pcm_dmix_sync_ptr(pcm);
486 if (err < 0)
487 return err;
488 /* fallthru */
489 case SNDRV_PCM_STATE_PREPARED:
490 case SNDRV_PCM_STATE_SUSPENDED:
491 case STATE_RUN_PENDING:
492 *delayp = snd_pcm_mmap_playback_hw_avail(pcm);
493 return 0;
494 case SNDRV_PCM_STATE_XRUN:
495 return -EPIPE;
496 case SNDRV_PCM_STATE_DISCONNECTED:
497 return -ENODEV;
498 default:
499 return -EBADFD;
500 }
501 }
That explains why mplayer always do snd_pcm_forward() after snd_pcm_delay():
snd_pcm_delay(0x122edc0, 0x7fff0c2201e0, 0x5f4ca4, 0, 0x11e1588) = 0
snd_pcm_forward(0x122edc0, 1756, 0xc0000000000026dc, 9948, 0x11e1588) = 0
snd_pcm_delay(0x122edc0, 0x7fff0c2201c0, 24000, 0x122da98, 0x11e1588) = 0
snd_pcm_forward(0x122edc0, 8, 0xc000000000002008, 8200, 0x11e1588) = 0x3ffffffffffff924
The mplayer get_delay() code reads:
MPlayer-1.0rc2/libao2/ao_alsa.c
869 /* delay in seconds between first and last sample in buffer */
870 static float get_delay(void)
871 {
872 if (alsa_handler) {
873 snd_pcm_sframes_t delay;
874
875 if (snd_pcm_delay(alsa_handler, &delay) < 0)
876 return 0;
877
878 if (delay < 0) {
879 /* underrun - move the application pointer forward to catch
up */
880 #if SND_LIB_VERSION >= 0x000901 /* snd_pcm_forward() exists since
0.9.0rc8 */
881 snd_pcm_forward(alsa_handler, -delay);
882 #endif
883 delay = 0;
884 }
885 return (float)delay / (float)ao_data.samplerate;
886 } else {
887 return(0);
888 }
889 }
Which is called in the following places:
3 mplayer.c playing_audio_pts 1601 audio_out->get_delay();
4 mplayer.c fill_audio_out_buffers 1823 else if (audio_eof && mpctx->audio_out->get_delay() < .04) {
5 mplayer.c sleep_until_update 1841 float delay = mpctx->audio_out->get_delay();
6 mplayer.c update_video 2026 float delay = playback_speed*mpctx->audio_out->get_delay();
It happen to not cause trouble because
1) in mplayer, the negative delay will be reset to 0 before being returned
2) in ALSA, snd_pcm_playback_forward() will do nothing if avail is negative
Thanks,
Fengguang
^ permalink raw reply [flat|nested] 3+ messages in thread
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