Open Sound System
OSS 4.x Programmer's Guide

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Returns labels for the currently available recording sources


oss_mixer_enuminfo namelist;
ioctl(fd, SNDCTL_DSP_GET_RECSRC_NAMES, &namelist);

The above code fragment lacks all error checks for clarity. Real world applications must always check for the errors and handle them as described below. Also most OSS ioctl calls will return information in the argument variable and it's usually necessary to check it too.


This ioctl call returns the list of currently available recording sources (labels) for this audio device file. See the Audio input and output volumes and routings section for more information about audio routings.

The following fields are available in the oss_mixer_enuminfo structure returned by this call.

To get the label for a given label number (0..N) the application can index the strings field in the following way: namelist.strings[namelist.strindex[n]].

The label length should usually be at most 8 characters. However this is not always possible. The application should be able to show at least 8 character positions. If the label is too long it's better to remove some characters from the middle rather than from the end because the last positions usually contain a running number.

There are absolutely no predefined routing names. The name set is fully dynamic and in some cases the ene duser may change it on fly. The names are intended to be human readable. Even it may look like devices have common names like "mic" or "line" this is not the case. Applications assuming this will fail in situations where they get changed to something like "guitar1" or "organs". So the application must present the names to the end user and ask him/her to select among them.

Related ioctl calls

Compatibility issues

This ioctl call is new in OSS 4.0 and not supported by the freeware implementations based on older OSS versions. If this call returns errno=EINVAL then the best approach is to assume that the recording source is not selectable. In this situation it's better to ask the user to change the recording source manually rather than trying to use desperate hacks to change the recording source.

Traditionally many audio applications have used the mixer ioctl calls to change the recording source. This must be avoided because in practice no program does this correctly. In addition the only correct way doesn't work with the freeware OSS clones anyway.

Please look at the When OSS audio ioctl calls can be made section for information about DSP ioctl call ordering.

OSS ioctl return values

The return value from the OSS ioctl calls will be -1 if a fatal error occurred. Other values mean that the ioctl call was more or less successful. However in most cases the application must check the value returned in the argument to see what was the accepted value.

Please see the Possible error codes (errno) returned by OSS calls section for more info about the error codes returned by OSS.

Sample programs

ossplay.cSources for the ossplay audio player and for the ossrecord
recsrc.cA sample program for recording source selection

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