[ALSA - driver 0000557]: SNDCTL_DSP_GETOPTR not working correctly in specific situation

[bugtrack@alsa-project.org]

A NOTE has been added to this issue.
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<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=557> 
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Reported By:                minmax
Assigned To:                
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Project:                    ALSA - driver
Issue ID:                   557
Category:                   CORE OSS - pcm
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     new
Distribution:               Debian unstable
Kernel Version:             vanilla 2.6.7
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Date Submitted:             10-01-2004 16:18 CEST
Last Modified:              04-09-2005 16:22 CEST
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Summary:                    SNDCTL_DSP_GETOPTR not working correctly in specific
situation
Description: 
When the first few writes to the oss emulation device are done in specific
way, SNDCTL_DSP_GETOPTR returns wrongly huge results in info.bytes
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 jdthood - 04-09-05 16:09 
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Submitter: Does this bug still exist?  Can you give more details about the
specific situation in which it appears?

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 minmax - 04-09-05 16:22 
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i've got new laptop since i reported this bug.

I've stumbled upon a bug when using Cinelerra (video editing software),
and since then i have patched the software to ignore the excessively wrong
results gotten from SNDCTL_DSP_GETOPTR

        if(!ioctl(get_output(0), SNDCTL_DSP_GETOPTR, &info))
        {
//printf("AudioOSS::device_position %d %d %d\n", info.bytes,
device->get_obits(), device->get_ochannels());
// workaround for ALSA OSS emulation driver's bug
// the problem is that if the first write to sound device was not full
lenght fragment then
// _GETOPTR returns insanely large numbers at first moments of play
                if (info.bytes > 2100000000)
                        return 0;
                else
                        return info.bytes /
                                (device->get_obits() / 8) /
                                device->get_ochannels();
        }

Issue History
Date Modified  Username       Field                    Change              
======================================================================
10-01-04 16:18 minmax         New Issue                                    
10-01-04 16:18 minmax         Distribution              => Debian unstable 
10-01-04 16:18 minmax         Kernel Version            => vanilla 2.6.7   
10-02-04 10:52 minmax         Issue Monitored: minmax                      
04-09-05 16:09 jdthood        Note Added: 0004406                          
04-09-05 16:22 minmax         Note Added: 0004410                          
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