[linux-dvb] gnutv: What causes DVR overflow?

David Liontooth lionteeth at cogweb.net
Thu Dec 2 06:46:20 CET 2010


On 11/29/2010 05:24 AM, Devin Heitmueller wrote:
> On Mon, Nov 29, 2010 at 2:54 AM, David Liontooth<lionteeth at cogweb.net>  wrote:
>> I'm seeing great results with gnutv on HVR-1850 cards, but each recording
>> triggers the message
>>
>>   DVR overflow
>>
>> What is this, and what are the typical causes? What can I do to prevent it
>> from happening?
> I don't know about gnutv specifically, but I do know that -EOVERFLOW
> is returned when an application fails to read the
> /dev/dvb/adapterX/dvr0 device fast enough.  It's the driver signaling
> to the application that it did not read the file handle often/fast
> enough and that the driver is going to drop packets to keep up.
>
> The driver has a limited amount of buffering, so if you have a delay
> that is too long between read() calls (or your read buffer is too
> small to accommodate the data rate) you will encounter this condition.
Thanks, Devin! On my end, it looks like the DVR overflow was caused by 
the -out file being on a mirrored OS drive; I've moved output to a 
separate drive and don't see the error any more. If I run into this 
again, are there ways to make this more robust -- for instance, increase 
the cache size, either as a parameter to the kernel module, or in gnutv?

Cheers,
Dave




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