Re: [Libcvd-members] libcvd cvd/videofilebuffer.h cvd/videofilebuffe...

[Ethan Eade]

Edward Rosten wrote:

> >         RawVideoFileBuffer is now a templated class. This allows the
> > VideoFileBuffer to correctly return frames of type Rgb<byte>.
> >    
>
>
> As fas as I knew, the previous system worked with Rgb<byte> frames. Was 
> this not the case?
>
> I would prefer it if the code (of which there is a large amount) is kept 
> in the .cc file, since RawVideoFileBuffer contains almost no type 
> dependent code.
>
> Essentially, at some point a cast has to happen between ffmpeg's data 
> (uint_8) and the compile time CVD image type. In the new version, this 
> happens on line 433 (videofilebuffer.h, version 1.12). The only other 
> piece of type dependent code is in the allocation of a memory buffer (must 
> be 3x bigger for Rgb). This could be allocated in VideoFileBiffer 
> and the data passed as a void pointer, or simply 3x the memory could be 
> allocated (the old version).
>  
My understanding of the problem, from briefly looking at the code with 
Colin, is that an image constructed as Image<byte> was being destructed 
as Image<Rgb<byte> >, which is bad (and aborts because of how 
aligned_mem registers buffers). 

I suspect the type dependent code can be factored out while still 
choosing the right destructor; I think the problem is that no one was 
using this code in whatever configure settings Colin is currently using, 
so the bug wasn't discovered until now, and Colin needed it to work.

Since we are already linking against a library, I agree that it's best 
to keep as much as possible in the library instead of headers.  If it 
were a mostly-header library, on the other hand... well, I've been known 
to embrace 45 second compiles.

- Ethan