At Wed, 19 Aug 2009 12:29:59 +0200, Stefan Schoenleitner wrote: > > Hi, > > I managed to write an ioplug plugin which dumps a raw PCM stream to a > file (similar to the way the file or tee plugins do, but without a slave > device). > > However, instead of immediately writing all the samples to the file, I > would like to add some delay so that the samples are written to the file > in real time at the frequency of the sampling rate. > > Thus if there is a single channel stream with 16bits being played at a > sampling rate of 8kHz, each 1/8000sec exactly 16 bits should be written > to the file. > > The reason for this is that I have a DSP attached over SPI which needs > exactly one audio sample per interval. > In order to talk to the DSP there is a SPI device-file which my ioplugin > would use to write the samples to. > > What is the best way to implement such a delay ? > > I'm pretty sure that just adding some usleep calls() won't work very > well, since the write operations to the device file probably don't take > the same amount of time every time. > Maybe it would work with non-blocking writes to the device file and a > high precision timer ? hrtimer would be the most accurate method, I guess. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
