On Tue, 06 Jan 2004 15:31:43 +0100 Holger Waechtler <[EMAIL PROTECTED]> wrote:
When a buffer overflows the ringbuffer pointers are reset, errno is set to EOVERFLOW. The data that has been previously in the ringbuffer will get lost.
And the read call returns -1, easily causing the reading program to stop reading (if there isn't a special case handling).
POSIX requires you to check errno in case of a return value of -1. Then you see errno=EOVERFLOW and see that it's not a critical error. Maybe you want to flush/reset some of your program's buffers and log an error message, then you can continue.
so the limit can't be even raised. The default is 10*1024*188 bytes (which is only one second with HDTV at 15Mbit/s).
You don't want to write a program that reads and processes the stream only every second, right? This would cause pretty heavy latencies...
Well, even if the program is not designed to wait one second it can easily happen under heavy system activity.
As regards latencies, in some cases I'm not interested in them at all; for example a cat /dev/dvb/adapter0/dvr0 >recording.ts with several megabytes of buffer would be very robust. Think about it this way: I need just around 2MB/s of throughput and an autorefreshed page in Mozilla ruins my recording, on a machine with 800 megabytes of free RAM, because we actually use only a little part of it to smooth the stream flow. Isn't it reasonable to have a huge buffer in such a case?
Have you tried buffering in userspace?
$ cat /dev/dvb/adapter0/dvr0 | buffer [size] > recording.ts
This should work...
In any case - just implement the missing code and send a patch, your contribution is welcome!
:)
Holger
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