[linux-dvb] Re: EOVERFLOW with section filter

[Gerard MAULINO <gmaulino@club-internet.fr>]

Johannes Stezenbach wrote:

> On Sun, Jan 19, 2003 at 09:50:28AM +0100, Gerard MAULINO wrote:
>  
> > I use a program that do that (ie:  read 3 bytes, then read the rest of 
> > the section). It works for me and it has the advantage to work with the 
> > "world" of reading section. I mean reading from a file or a socket.
> >    
> Yes, it may be advantageous that the same read logic works on
> any type of file descriptor.
>
>  
> > I don't know what's the better way to implement this, but I know that most 
> > of data sections in the french air are less than 4kb and also than 1kb 
> > (BAT, EIT, SDT...). So if you need to get about ten megas of data cutted 
> > in sections of 2kb you will probably lost time and space using a read of 
> > 4k's buffer.
> >    
> The section_length field has only 12 bits, so the section size is
> limited to 4096. For most sections the size is further limited by
> specification to 1024 bytes. So, at the expense of a few bytes
> of "wasted" buffer space you get the section using one read() system
> call instead of two. And the fixed buffer size makes it easier to
> use buffer pools and thus avoiding a malloc() per section.
>
> Regards,
> Johannes
>
>
>  
Ok, it's a good thing that the driver let you get one section even if 
you read more than 'section_lenght'. I will try this.

Thanks,

Gerard.



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