Yeah, I am looking for some sample application to test forward/rewind functionality. Regards, Anuj On Thu, Sep 24, 2009 at 1:27 PM, Raymond Yau <superquad.vortex2@xxxxxxxxx> wrote: > Do you mean that there is no test program to verify the implementation is > correct ? > > Some sound card 's hardware has FIFO buffer. > > For example , au88x0 > > according to patent 6167465 > > Additionally, a first-in-first-out (FIFO) buffer is established for the DMA > channel. Then a DMA request is generated in order to begin filling the FIFO > buffer with data from the first data segment 150(0) using the information > provided by CPU 210. > > > The FIFO buffer may be any suitable size capable of handling bus latencies > while small enough such that the memory requirement is not overly > burdensome. In one embodiment of the present invention, the FIFO buffer is > 32 samples or words in depth, which would withstand a maximum bus latency of > about 4 microseconds. By way of example, if 48 DMA channels trigger > simultaneously, with a trigger level set at half the buffer size (16 > samples), each DMA channel can wait 16 samples (20 microseconds per sample), > or approximately 320 microseconds before running out of data. > > > It seem that alsa-lib should not allow application to rewind the application > pointer to hardware pointer since you cannot write the next sample because > of FIFO buffer even using mmap read/write > > or bug in *snd_pcm_rewindable() ?* > > > 2009/9/24 Takashi Iwai <tiwai@xxxxxxx> > >> At Thu, 24 Sep 2009 13:04:24 +0530, >> Anuj Aggarwal wrote: >> > >> > Hi, >> > >> > I want to try the forward/rewind APIs supported by the ALSA library. >> > Can someone point to an ALSA application which exercises these APIs? >> >> Pulseaudio is using snd_pcm_rewind(). >> About snd_pcm_forward(), I don't know of... >> >> >> Takashi >> _______________________________________________ >> Alsa-devel mailing list >> Alsa-devel@xxxxxxxxxxxxxxxx >> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel >> > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > -- Best Regards, Anuj Aggarwal _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
