Thanks Jaroslav for your fast reply, Jaroslav Kysela wrote: > On Fri, 4 Aug 2006, Eric Peters wrote: > > >>Dear all, >> >>I have a PCM device which is playing some PCM samples. The soundbuffer >>is pretty full. And now I want to pause the buffer immediately (as >>fast as possible) and sometime later I want to resume at exactly this >>sample I paused. >> >>Now I found the two functions snd_pcm_pause and snd_pcm_resume. But >>unfortunately these functions aren't supported by all hardware. > > > Right. > > >>Or do you have an idea how to implement such a feature? I also found >>the two functions snd_pcm_drain and snd_pcm_drop. But when I use this >>functions the sound buffer will be empty if I resume. And with >>snd_pcm_drain there will be a delay between I pause the playback and >>there are no more samples out of my spaekers. > > > If hw pause/resume is supported - check snd_pcm_hw_params_can_pause(), > then you may use it, otherwise you should implement the pause in this way: > > on pause: > > 1) remember the current position in playback buffer (using snd_pcm_delay()) > 2) use snd_pcm_drop() to stop the stream immediately > > on resume: > > 3) fill ring buffer from the position saved in 1) > 4) restart playback > > In other words, if hardware does not support pause, application must > "emulate" this behaviour. Yes, you're right. But I'm not sure if I understand your suggestion. In 1) I will remember the current position of the playback buffer. If I use snd_pcm_drop in 2) I will lose all frames I already put into the playback buffer, or not? If so, for 3) I have to know which samples I dropped so I can rewrite them to the playback buffer, right? Or aren't the frames which I already have written into the sound buffer lost if I call snd_pcm_drop?? If so, I can write new frames to the position I remembered in 1). Best regards, Eric > > Jaroslav > > ----- > Jaroslav Kysela <perex@xxxxxxx> > Linux Kernel Sound Maintainer > ALSA Project, SUSE Labs ------------------------------------------------------------------------- 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
