[alsa-devel] Application supporting forward/rewind APIs

Raymond Yau superquad.vortex2 at gmail.com
Wed Oct 7 08:58:23 CEST 2009

It seem that the difference between the application pointer and the hardware
pointer is just the theoretical value which none of the sound card can

static snd_pcm_sframes_t snd_pcm_hw_rewindable(snd_pcm_t *pcm)
    return snd_pcm_mmap_hw_avail(pcm);

To allow the application rewind the application pointer to hardware pointer
and rewrite the next sample immediately at any time

The audio controller have to fetch the audio data as the same rate as the
sampling rate.

The practical value may be the difference between the application pointer
and the nearest period boundary

2009/9/24 Takashi Iwai <tiwai at suse.de>

> 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 at alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel

More information about the Alsa-devel mailing list