At Wed, 5 May 2004 11:13:20 +0200, "" <[EMAIL PROTECTED]> wrote: > > Mensaje citado por Takashi Iwai <[EMAIL PROTECTED]>: > > > At Tue, 27 Apr 2004 20:36:29 +0200, > > Juan Carlos Granda wrote: > > > > > > [1 <text/plain; iso-8859-1 (quoted-printable)>] > > > > > > [2 <text/html; iso-8859-1 (quoted-printable)>] > > > Hi, > > > > > > I'm developing a Multi-thread app for capturing audio+video and i have a > > few > > > questions. The app is based on 3 threads: > > > > > > - 1 thread for capturing audio using ALSA lib. > > > - 1 thread for capturing video using V4L2. > > > - 1 thread for saving audio+video into an AVI file. > > > > > > Both of capturing threads store captured data into a queue and the last > > thread picks > > > the data and sync A/V. > > > > > > I start audio capturing and then the video. So, i need to known the point > > of the > > > stream of audio the video begins. > > > I'm readings frames by period size times. My prob is how to get valid ALSA > > timestamps > > > to eliminate the previous frames of the period the video starts. I've > > tried > > > snd_pcm_status_get_trigger_tstamp but it returns the same timestamp for a > > long period > > > of time (13 secs) (is it related to the period or buffer time?). I've > > tried > > > snd_pcm_status_get_tstamp too but i obtain a delay of several microseconds > > from the > > > period time (50 - 100 more or less) (is it because the clock resolution?). > > > > the alsa-driver can put timestamp at each period update. > > set SND_TSTAMP_MMAP in snd_pcm_sw_params_set_tstamp_mode(). > > > > > > Takashi > > > > > > I set SND_TSTAMP_MMAP like you told me. What function may i use? I've tried > snd_pcm_status_get_trigger_tstamp and snd_pcm_status_get_tstamp, and the first > always return the same timestamp or it changes every 4 or 6 seconds. And the > second returns the "now" timestamp. What am i doing wrong?
no, you're not wrong, i overlooked that the SND_PCM_STATUS ioctl calls the update of timestamp. so, apparently there is no this timestamp mode for the period-updates. but, anyway, you can get the sound frame position and the timestamp at the same time. it should suffice to calculate the sync, i believe. Takashi ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
