Alsa Library for transcoding
Can I use ALSA library for transcoding of audio from one format to another.
i.e S32 2 channels to S16 1 Channel audio from file as input source to file output
In one of link I saw statement,
Plugin: File
This plugin stores contents of a PCM stream to file or pipes the stream to a command, and optionally uses an existing file as an input data source (i.e., "virtual mic")
How to setup such pipeline file input and file output, when it is input from file from where does it pick information like format and channels since, API "snd_pcm_file_open" doesn't ask for format related information ? I am hoping this to come from configuration file .asoundrc but, I don't see any doucmentation on how to do it ?
libalsa
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
add a comment |
Can I use ALSA library for transcoding of audio from one format to another.
i.e S32 2 channels to S16 1 Channel audio from file as input source to file output
In one of link I saw statement,
Plugin: File
This plugin stores contents of a PCM stream to file or pipes the stream to a command, and optionally uses an existing file as an input data source (i.e., "virtual mic")
How to setup such pipeline file input and file output, when it is input from file from where does it pick information like format and channels since, API "snd_pcm_file_open" doesn't ask for format related information ? I am hoping this to come from configuration file .asoundrc but, I don't see any doucmentation on how to do it ?
libalsa
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
add a comment |
Can I use ALSA library for transcoding of audio from one format to another.
i.e S32 2 channels to S16 1 Channel audio from file as input source to file output
In one of link I saw statement,
Plugin: File
This plugin stores contents of a PCM stream to file or pipes the stream to a command, and optionally uses an existing file as an input data source (i.e., "virtual mic")
How to setup such pipeline file input and file output, when it is input from file from where does it pick information like format and channels since, API "snd_pcm_file_open" doesn't ask for format related information ? I am hoping this to come from configuration file .asoundrc but, I don't see any doucmentation on how to do it ?
libalsa
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
Can I use ALSA library for transcoding of audio from one format to another.
i.e S32 2 channels to S16 1 Channel audio from file as input source to file output
In one of link I saw statement,
Plugin: File
This plugin stores contents of a PCM stream to file or pipes the stream to a command, and optionally uses an existing file as an input data source (i.e., "virtual mic")
How to setup such pipeline file input and file output, when it is input from file from where does it pick information like format and channels since, API "snd_pcm_file_open" doesn't ask for format related information ? I am hoping this to come from configuration file .asoundrc but, I don't see any doucmentation on how to do it ?
libalsa
libalsa
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
edited Nov 19 '18 at 9:39
vishwanath patil
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
asked Nov 19 '18 at 8:37
vishwanath patilvishwanath patil
217
217
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
It can't be done since configuration file (asoundrc) as only option to set input file and format as raw or wav as below
pcm.file {
format raw
infile "/home/root/raw.pcm"
}
since you can't specify input format you can't transcode, it reads in format that you request from that file. i.e it reads S32 if you request S32 through arecord even if file contains S16.
But, alternative is to use tools like "sox" for transcoding.
If it is only to check how does ALSA does transcoding when real mic is present,then dump "snd_pcm_dump" (arecord -v) will give conversion function(equation) that it uses
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53370944%2falsa-library-for-transcoding%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It can't be done since configuration file (asoundrc) as only option to set input file and format as raw or wav as below
pcm.file {
format raw
infile "/home/root/raw.pcm"
}
since you can't specify input format you can't transcode, it reads in format that you request from that file. i.e it reads S32 if you request S32 through arecord even if file contains S16.
But, alternative is to use tools like "sox" for transcoding.
If it is only to check how does ALSA does transcoding when real mic is present,then dump "snd_pcm_dump" (arecord -v) will give conversion function(equation) that it uses
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
add a comment |
It can't be done since configuration file (asoundrc) as only option to set input file and format as raw or wav as below
pcm.file {
format raw
infile "/home/root/raw.pcm"
}
since you can't specify input format you can't transcode, it reads in format that you request from that file. i.e it reads S32 if you request S32 through arecord even if file contains S16.
But, alternative is to use tools like "sox" for transcoding.
If it is only to check how does ALSA does transcoding when real mic is present,then dump "snd_pcm_dump" (arecord -v) will give conversion function(equation) that it uses
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
add a comment |
It can't be done since configuration file (asoundrc) as only option to set input file and format as raw or wav as below
pcm.file {
format raw
infile "/home/root/raw.pcm"
}
since you can't specify input format you can't transcode, it reads in format that you request from that file. i.e it reads S32 if you request S32 through arecord even if file contains S16.
But, alternative is to use tools like "sox" for transcoding.
If it is only to check how does ALSA does transcoding when real mic is present,then dump "snd_pcm_dump" (arecord -v) will give conversion function(equation) that it uses
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
It can't be done since configuration file (asoundrc) as only option to set input file and format as raw or wav as below
pcm.file {
format raw
infile "/home/root/raw.pcm"
}
since you can't specify input format you can't transcode, it reads in format that you request from that file. i.e it reads S32 if you request S32 through arecord even if file contains S16.
But, alternative is to use tools like "sox" for transcoding.
If it is only to check how does ALSA does transcoding when real mic is present,then dump "snd_pcm_dump" (arecord -v) will give conversion function(equation) that it uses
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
answered Nov 27 '18 at 16:47
vishwanath patilvishwanath patil
217
217
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53370944%2falsa-library-for-transcoding%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
