> > The following might be for the record, or interesting for developers: > > For the Lumiera development, we did some primary experiments with ALSA, and > from there I know the "inward view". As a programmer, you definitively must > do more elaborate configuration steps to open ALSA successfully with the > hammerfall driver for the Multiface. There is a standard basic configuration > which you find in most ALSA tutorials. This code just opens a two channel > inteface with 16bit integer samples. This works for most consumer grade > interfaces but seemingly doesn't work for the Multiface. > > In our preliminary experiments, we found out that we needed to set the > correct number of channels (all of them!), and we needed to set > * SND_PCM_ACCESS_RW_NONINTERLEAVED > (many tutorials and examples propose instead to use > SND_PCM_ACCESS_RW_INTERLEAVED)
Interesting. If I were HW designer, I preferred SND_PCM_ACCESS_RW_INTERLEAVED, the design will be much simpler. > * and as output sample format, we found most formats to be rejected > immediately. With the exception of > SND_PCM_FORMAT_UNKNOWN > SND_PCM_FORMAT_S32 > The latter setting (32bit floating point samples) seems to be the right > way to go, based on the properties and specs of the Multiface > SND_PCM_FORMAT_S32 is 32bit signed integer. Why should a sound card accept floating point samples? > > We will continue to work on this stuff. What I want is to find a way to > write that ALSA code, so it can work with a wide range of interfaces and > allows to configure the necessary bits. This is a bit more challenging > than just rewriting some example code. But right now other things are > more important (for Lumiera) and, as usual, we're lacking developers ;-) > There is an interesting article http://www.volkerschatz.com/noise/alsa.html. This helped me to understand why ALSA interface is so complex and how it is intended to use. Einar _______________________________________________ Cinelerra mailing list [email protected] https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
