Re: [Alsa-user] dual mono
Ran Shalit wrote: I am using card with playback device and capture device. It seems to me that playback has 2 channels and capture has 2 channels each. The physical connection is:] * mic input * line input * line output * headphones output The routing is typcially handled with mixer controls. Regards, Clemens -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] dual mono
Dual mono is indeed an AAC-related concept. When you record multiple channels using ALSA, they are always independent, i.e., ALSA does not make any assumptions about the sample values in the channels (or, for that matter, about consecutive samples in the same channel). In other words, you need not (and cannot) tell ALSA whether the channels are related in any way. Hi, Thank you for the information. I understand that mono/stereo is not related to ALSA (probably only to the compression method, external to ALSA) I hope you can help me understand better the idea of channels with alsa. I am using card with playback device and capture device. It seems to me that playback has 2 channels and capture has 2 channels each. The physical connection is:] - mic input - line input - line output - headphones output This is the proc info = root@dm814x:/mnt/nfs# cat /proc/asound/card0/pcm1p/info card: 0 device: 1 subdevice: 0 stream: PLAYBACK id: AIC3X tlv320aic3x-hifi-1 name: subname: subdevice #0 class: 0 subclass: 0 subdevices_count: 1 subdevices_avail: 1 root@dm814x:/mnt/nfs# root@dm814x:/mnt/nfs# cat /proc/asound/card0/pcm1c/info card: 0 device: 1 subdevice: 0 stream: CAPTURE id: AIC3X tlv320aic3x-hifi-1 name: subname: subdevice #0 class: 0 subclass: 0 subdevices_count: 1 subdevices_avail: 1 I have looked in the use APIs of alsa, but I can't figure out the channel usage for controlling the route. If for example I want to capture only one of the channels (mic in), how do I do it using snd_xxx api ? The same goes with playback, which API do I have so that I control the data for specific channel ? Thank you! Ran -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] dual mono
Hi Ran, I don't think ALSA APIs offer any mono or stereo abstraction. The API enables you to define a sample format and a sampling rate for one channel, then the number of channels (at least in pcm). You can configure your access point with two channels and use them according to your device design, such as dual mono. I might have overlooked something though, please anyone correct me I am wrong. Regards, Sam 2015-07-05 16:24 GMT+02:00 Ran Shalit ransha...@gmail.com: Hello, I am new with ALSA project. I would like to ask if dual mono, is used in ALSA APIs, or wether it is the same as stereo. Thank you, Ran -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] dual mono
Ran Shalit wrote: On Sun, Jul 5, 2015 at 9:06 PM, Clemens Ladisch wrote: Ran Shalit wrote: I would like to ask if dual mono, is used in ALSA APIs, or wether it is the same as stereo. What exactly do you mean? I actually need to do the following: analog audio from 2 channels -- encode using ALSA into PCM format -- encode to AAC I know that there is a concept of dual mono and concept of stereo when coding the audio format. But I probably went wrong, and this is NOT related to ALSA encode, but to the AAC encoding. Dual mono is indeed an AAC-related concept. When you record multiple channels using ALSA, they are always independent, i.e., ALSA does not make any assumptions about the sample values in the channels (or, for that matter, about consecutive samples in the same channel). In other words, you need not (and cannot) tell ALSA whether the channels are related in any way. Regards, Clemens -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] dual mono
Ran Shalit wrote: I would like to ask if dual mono, is used in ALSA APIs, or wether it is the same as stereo. What exactly do you mean? Regards, Clemens -- Don't Limit Your Business. Reach for the Cloud. GigeNET's Cloud Solutions provide you with the tools and support that you need to offload your IT needs and focus on growing your business. Configured For All Businesses. Start Your Cloud Today. https://www.gigenetcloud.com/ ___ Alsa-user mailing list Alsa-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
