[alsa-devel] PCM substream
Hi All,
From the last couple of days, I have been trying to understand the Linux
Alsa Subsystem.I have read the Alsa Driver API and Application API's. But I could not understand the concept of PCM substreams, Could you please give me some pointers to get a good understanding on the PCM substream.
regards, Arun.
arun kumar wrote:
From the last couple of days, I have been trying to understand the Linux Alsa Subsystem.I have read the Alsa Driver API and Application API's. But I could not understand the concept of PCM substreams,
A PCM stream has one or more substreams. Multiple substreams are used when the hardware can mix them together for one output. This was used in old wavetable sound cards; nowadays, you almost always have one substream.
Regards, Clemens
Hi Clemens,
Thanks for the reply.So, if any application tries to open more than one substream will it get the error? or alsa subsystem gives it one more substream and helps in mixing of substreams considering my hardware has only support for one substream.
regards, Arun. On Thu, Aug 9, 2012 at 6:19 PM, Clemens Ladisch clemens@ladisch.de wrote:
arun kumar wrote:
From the last couple of days, I have been trying to understand the Linux Alsa Subsystem.I have read the Alsa Driver API and Application API's.
But I
could not understand the concept of PCM substreams,
A PCM stream has one or more substreams. Multiple substreams are used when the hardware can mix them together for one output. This was used in old wavetable sound cards; nowadays, you almost always have one substream.
Regards, Clemens
(please don't top-post)
arun kumar wrote:
So, if any application tries to open more than one substream will it get the error?
If there is no free substream available, the application will get an error.
(If some mixing sound server like PulseAudio is used, this does not matter.)
Regards, Clemens
2012-8-9 下午8:49 於 "Clemens Ladisch" clemens@ladisch.de 寫道：
arun kumar wrote:
From the last couple of days, I have been trying to understand the Linux Alsa Subsystem.I have read the Alsa Driver API and Application API's.
But I
could not understand the concept of PCM substreams,
A PCM stream has one or more substreams. Multiple substreams are used
when
the hardware can mix them together for one output. This was used in old wavetable sound cards; nowadays, you almost always have one substream.
There are some hda controllers support multi-stream capture and some hda codecs have two or more adc which allow two applications using different mic
List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 3/3 Subdevice #0: subdevice #0 Subdevice #1: subdevice #1 Subdevice #2: subdevice #2
participants (3)
-
arun kumar -
Clemens Ladisch -
Raymond Yau