Matroska crashes (memory exhausted)

[albertogs]

I am trying to get the information from a Matroska file.

Since I am doing that in an online manner, I just get some kb. from each file (16kb usually) and create a temporal file.

Then, I pass that temporal file to getID3(). It works fine with other formats, and gives me a warning like this:
Probably truncated file - expecting 424603822 bytes of data, only found 6128 (short by 424597694 bytes)

However, talking about matroska, it changes quite a bit.

Unless it is 4kb size or smaller (the temporal file, which gives me almost no information) I get this error:
Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 32769 bytes) in PATH/module.audio-video.matroska.php on line 1377

I tried to grow it (the memory limit) up to 250 MB, but it still crashes.

Any idea?