[mythtv-users] Permissions on devices?

[Joe Schmidt]

Yup, I'm a member of the audio group. Also tried running as root with 
similar results.

I just tried the dd command you suggested. I heard a pop of sound on the 
headphones that I used to get in DOS when I'd load up a game that makes 
use of my "Soundblaster or Compatible" :-) No errors.

I also tried using aplay to play some WAVs I had installed. Some WAVs 
played with errors, others didn't play.

This one didn't work...

# aplay ktalkd.wav
Playing WAVE 'ktalkd.wav' : Unsigned 8 bit, Rate 11025 Hz, Mono
aplay: set_params:847: Can't use period equal to buffer size (5513 == 5513)

This one sounded fine...
# aplay pop.wav
Playing WAVE 'pop.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono
ALSA lib pcm_hw.c:510:(snd_pcm_hw_drop) SNDRV_PCM_IOCTL_DROP failed: 
File descriptor in bad state
ALSA lib pcm_hw.c:347:(snd_pcm_hw_hw_free) SNDRV_PCM_IOCTL_HW_FREE 
failed: File descriptor in bad state



Barry Davis wrote:

> try this:
>    dd if=/dev/zero of=/dev/dsp0
>
> If this fails straight away then you won't be able to get anywhere 
> with an application that needs sound like mythtv. If it works press 
> CtrlC to stop it otherwise it will go on for ever.
> Seeing as you have devfs and this file exists (/dev/dsp) I'm pretty 
> confident that you sound is working.
> You can change the ownership of /dev/dsp to yourself using chown 
> user:group /dev/dsp, but that will be tempoary, next time you reboot 
> it will be recreated with the original ownership.
>
> Did you try adding yourself to the audio group?
>
> Joe Schmidt wrote:
>
>> When I checked out the /etc/devfsd.conf, it appeared to me that 
>> /dev/sound/dsp was the one that was set to belong to the audio group! 
>> So I went into setup, set it to use that as the audio capture device, 
>> and tried out the frontend again. Here's my new errors:
>>
>> Delaying to next trigger: 22044990
>> Delaying to next trigger: 32635596
>> Audio buffer overflow, audio data lost!
>> Audio buffer overflow, audio data lost!
>> Audio buffer overflow, audio data lost!
>>
>> And when I use /dev/dsp0...
>>
>> lotus mythtv # mythfrontend
>> connecting to backend server: 127.0.0.1:6543
>> adding: lotus.njit.edu as a player 1
>> adding: lotus.njit.edu as a player 0
>> adding: lotus.njit.edu as a player 0
>> adding: lotus.njit.edu as a remote ringbuffer
>> Changing from None to WatchingLiveTV
>> opened vbi device
>> Changing from None to WatchingLiveTV
>> strange error flushing buffer ...
>> Over/underscanning. V: 0.000000, H: 0.000000, XOff: 0, YOff: 0
>> Using XV port 61
>> Delaying to next trigger: 18049700
>> Delaying to next trigger: 19382356
>> Delaying to next trigger: 17799915
>>
>> Barry Davis wrote:
>>
>>> If its a permission thing with devfs you either need to modify 
>>> /etc/devfsd.conf or you need to add you user name to the audio group 
>>> in /etc/group. There should be a line which reads "audio:x:17:root" 
>>> - change it to "audio:x:17:root,youruser".
>>> I think the audio devices get created with permissions 0660 for 
>>> groups root and audio when the soundcard module is pulled in.
>>> I don't have a soundcard in my work pc anymore so I can't be sure, 
>>> but I had it working last year.
>>>
>>> Joe Schmidt wrote:
>>>
>>>> Thanks for the reply! I'm using devfs, so maybe that handles 
>>>> symbolic links in /dev a bit differently. *shrug*
>>>>
>>>> I now receive the following errors flooded through my screen when I 
>>>> try to watch live TV.
>>>>
>>>> only read -1 from 4096 bytes from '/dev/dsp'
>>>> read audio: File descriptor in bad state
>>>> ran out of free AUDIO buffers :-(
>>>>
>>>> I'm not sure what I'm doing wrong. Maybe I messed up installing 
>>>> ALSA somehow? I followed the instructions to the letter (I think..)
>>>>
>>>> Thanks for the continued help from everyone. :-)
>>>>
>>>>
>>>> Ray Olszewski wrote:
>>>>
>>>>> At 11:50 PM 5/7/2003 -0400, Joe Schmidt wrote:
>>>>> [...]
>>>>>
>>>>>> Thanks to the advice of someone else on the list, I think I have 
>>>>>> my sound card set up properly. However, I receive errors while 
>>>>>> trying to watch Live TV, and then exiting from LiveTV:
>>>>>> [...]
>>>>>>
>>>>>> Here are the permissions on the two dvices mentioned:
>>>>>> $ ls dsp -l && ls mixer -l
>>>>>> lr-xr-xr-x    1 root     audio           9 May  8 11:24 dsp -> 
>>>>>> /dev/dsp0
>>>>>> lr-xr-xr-x    1 root     root           11 May  8 11:24 mixer -> 
>>>>>> /dev/mixer0
>>>>>>
>>>>>> I tried changing dsp to group audio and making sure I was a 
>>>>>> member of audio, but it did not seem to make a difference. 
>>>>>> (Later, I noticed that all users have read and execute 
>>>>>> permissions anyway).
>>>>>>
>>>>>> How does everyone else have their permissions set up?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> The permissions you are listing are associated with the symlink, 
>>>>> not the underlying device. (And they look unlike any symlink 
>>>>> permissions I have ever seen ... on my systems, symlinks always 
>>>>> show up as "lrwxrwxrwx" ... perhaps someone can clarify that part?)
>>>>>
>>>>> Anyway ... check the permissions on the /dev/dsp0 and /dev/mixer0 
>>>>> . They need to be mode 660 (you need write permission in order to 
>>>>> use /dev/dsp0 for output) with group audio and the mythtv userid 
>>>>> part of group audio. (Obvious other variants are possible, such as 
>>>>> mode 666, but that's the setup I usually use.)
>>>>>