Re: gnutv: What causes DVR overflow?
On 11/29/2010 05:24 AM, Devin Heitmueller wrote: On Mon, Nov 29, 2010 at 2:54 AM, David Liontoothlionte...@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 -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: gnutv: What causes DVR overflow?
On Thu, Dec 2, 2010 at 12:46 AM, David Liontooth lionte...@cogweb.net wrote: 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? Hi David, There is an ioctl you can call against the demux filehandle to increase the size of the in-kernel buffer. However I have no idea whether the gnutv application currently plays with this value. I suspect you would probably have to add an ioctl() call to the gnutv source code. http://linuxtv.org/downloads/v4l-dvb-apis/dmx_fcalls.html#dms_set_buffer_size Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: gnutv: What causes DVR overflow?
On Mon, Nov 29, 2010 at 2:54 AM, David Liontooth lionte...@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. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
gnutv: What causes DVR overflow?
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? Could it be related to slow hard drives? I'm assuming an overflow results in some degree of corruption of the stream that I write to file. Cheers, Dave -- To unsubscribe from this list: send the line unsubscribe linux-media in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
