Takashi Iwai wrote: > At Wed, 07 Mar 2007 22:33:25 +0000, > James Courtier-Dutton wrote: >> Takashi Iwai wrote: >>> At Tue, 27 Feb 2007 15:52:41 +0100 (CET), >>> Jaroslav Kysela wrote: >>>> Hi, >>>> >>>> in 2.6 kernels, we can use ktime_get_ts() function to get >>>> monotonic time which can be used for PCM timestamps. I would propose to >>>> reuse the SNDRV_PCM_IOCTL_TSTAMP ioctl to enable using of monotonic clock. >>>> The "enable" (int) argument might mean: >>>> >>>> 0: standard clock - getnstimeofday() >>>> 1: standard clock - getnstimeofday() - for "compatibility" >>>> 2: monotonic clock - ktime_get_ts() >>> Good to add a new feature... but is there any user of this PCM >>> timestamp so far? I see some good purposes but rarely seen in the >>> reality, unfortunately... >>> >>> >>> Takashi >>> >> There are some good applications for it, but I have not got round to >> writing them yet! > > Me too ;) But, I remember some difficulties regarding the > timestamping at the last time I tried (quite ago). The timestamp is > somewhat hard to use because it's updated at each pointer or status > update although I wanted to get the exact time only at the period > boundary. Maybe these usability issues should be sorted out all > together. > > > Takashi Yes, timestamp at period boundary would be more useful. I had not looked at the current timestamp in enough details. A timestamp generated in the IRQ routine would probably be the best. Could the timestamp be attached to a particular PCM sample in the buffer. I.e. The app would retrieve the timestamp, and be told that that timestamp applies to the sample X samples from now, if using the snd_pcm_read() function. James ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
