Re: Recording Endlessly w/o Memory Overflow?

Dave,

Thank you very much for your reply. It was difficult to "dig" up
this post after the massive thread attack by some person :(

As you have suggested, the AVI compression was the issue. I just
tried the uncompressed format, and disk logging keeps up with the
memory. GREAT!

After all, I am only interested in few minutes of recording at a
time, this greatly enhances the ability for me to capture everything
without loss of the image quality.

Peter

PS MPEG4 seems to be not supported by the MATLAB???

Dave Tarkowski wrote:

>
> Peter,
>
> Your assumptions on what is happening is basically correct.
> Incoming data
> is buffered in memory before being written to disk. As frames are
> written
> to disk, the associated memory is cleared allowing new frames to be
>
> acquired. Logging to disk is a slow process and if it is slower
> than the
> rate of acquisition, you will eventually run out of memory.
>
> The easiest way to deal with this is to change the format of the
> log file.
> The AVIFILE command that you use below uses the Indeo5 codec by
> default.
> Indeo5 is used by default because it is available on almost all
> computers
> running Windows. However, it is fairly slow for real time
> compression. I
> would suggest trying one of two other options, depending on your
> needs. The
> first would be to use uncompressed video. This will create very
> large files
> on disk, but will preserve the integrity of your data. If the
> uncompressed
> data doesn't work for you, try specifying "mp42" as the compression
> type for
> AVIFILE. This uses the Microsoft MPEG 4 version 2 codec. This
> codec is
> pretty commonly available, and much faster than the Indeo5 codec.
>
> To do this change the line:
>
> aviobj = avifile('logfile.avi');
>
> to
>
> aviobj = avifile('logfile.avi', 'Compression', 'none'); %
> Uncompressed
>
> or
>
> aviobj = avifile('logfile.avi', 'Compression', 'mp42'); % MPEG
> 4
> compression
>
> -Dave Tarkowski
.

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