[mythtv-users] Permissions on devices?

Thu May 8 17:30:35 EDT 2003

What version of ALSA do you have?
You might need new drivers.
I know the ALSA drivers don't work on my work pc - Intel 82860 AC97 
compatible.
MP3s playing on this using alsa drivers causes playback to be too fast 
and shifted up an octave.
I'd suggest getting playback of you wav file sorted out first. Try new 
drivers and ask the people that make the ALSA drivers if it still 
doesn't work, or buy a new cheap soundcard.
What card was it that you have?

Joe Schmidt wrote:

> 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.)
>>>>>>
>
>
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