On Thu, 11 Feb 2010, Donald Tournier wrote: > Hi, > > We have an application in our institute that will require recording of > a digital signal via an optical cable. We have to be able to guarantee > perfect bitwise reproduction of the signal (the odd bit error is not a > problem). We're thinking of using SPDIF and ALSA to capture the signal > (obviously we'll have to make sure the signal is properly encoded to > begin with). > > However, after some initial attempts, it's becoming clear that ALSA > can't necessarily guarantee bitwise perfect capture. ALSA might change > the format, or resample the signal after capture (although I've heard > that can be turned off with "snd_pcm_hw_params_set_rate_resample > (capture_handle, hw_params, 0)"). Also, the card that we've been > playing with so far (SB Audigy2 ZS) apparently performs some low-pass > digital filtering on the input stream anyway, and is therefore no use > to us. Getting raw S/PDIF stream for EMU chips is not so easy. They operates internally at 48kHz and everything is resampled to this frequency. Jaroslav ----- Jaroslav Kysela <perex@xxxxxxxx> Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
