Please describe the problem:
When beagled is using its internal "FilterVideo" filter, it frequently gets stuck in an infinite loop when processing mpeg video files.  Normally you don't run into this problem because the "FilterMPlayerVideo" is usually used, but if mplayer is not installed on the system, then it falls back to "FilterVideo", and hangs.

Steps to reproduce:
1. Remove mplayer from your system (or temporarily disable it)
2. Put a corrupt .mpeg video file in the directory beagle is indexing
3. Let beagled start indexing

You can also reproduce this running beagle-extract-content on the corrupt file


Actual results:
beagled-helper hangs trying to filter the corrupt mpeg file, using 100% cpu indefinitely.  This prevents beagle from indexing any further, because it is stuck on this file.  If I remove the corrupt file, shutdown, and restart beagled, then it will proceed until it runs into the next corrupt file.

Expected results:
beagled-helper should give up processing the file once it can't find the information it is looking for (width and height I assume)

Does this happen every time?
This happens every time for corrupt or incomplete mpeg files

Other information:
The problem is an infinite loop in Filters/TagLib/Mpeg/File.cs  ReadVideoPacket function

Here is a version of that function which prevents the infinite loop:

void ReadVideoPacket (ref long position)
{
    Seek (position + 4);
    int length = ReadBlock (2).ToUShort ();
    long offset = position + 6;
    // Put a sanity limit on how long we search
    int sanity_limit = 1000;
    int i=0;

    while (!video_found && (i < sanity_limit) && offset < position + length) {
        if (FindMarker (ref offset) ==
            Marker.VideoSyncPacket) {
            video_header = new VideoHeader (this,
                offset + 4);
            video_found = true;
        } else {
            // Make sure we keep moving forward, because this one didn't match
            offset += 4;
        }
        i++;
    }

    position += length;
}