Issues with activating deinterlacing on mpeg4 material

http://forum.videolan.org/viewtopic.php?p=29913#29913

Trax has reported similar issues.... Start stream (mpeg4/xvid), turn on ext gui, turn on video filter -> crash. According to gibalou has something to do with decoder restarting; ffmpeg bug.

I get

[mpeg4 @ 0x8507614]hmm, seems the headers are not complete, trying to guess time_increment_bits [mpeg4 @ 0x8507614]my guess is 1 bits ;)

right before the crash

Here is the backtrace I get in gdb

Program received signal SIGFPE, Arithmetic exception.
[#0](https://code.videolan.org/videolan/vlc/-/issues/0)  0xb7ca84e7 in __divdi3 () from /lib/libgcc_s.so.1
[#1](https://code.videolan.org/videolan/vlc/-/issues/1)  0x082ddc7b in decode_vop_header (s=0x892d910, gb=0x892f45c) at h263.c:5858
[#2](https://code.videolan.org/videolan/vlc/-/issues/2)  0x082e7886 in ff_h263_decode_frame (avctx=0x89198c0, data=0x888ea80, data_size=0xb25c43b4, buf=0x8a26078 "", buf_size=1787) at h263dec.c:493
[#3](https://code.videolan.org/videolan/vlc/-/issues/3)  0x0818d1c5 in avcodec_decode_video (avctx=0x89198c0, picture=0x1, got_picture_ptr=0xb25c43b4, buf=0x1 <Address 0x1 out of bounds>, buf_size=1787) at utils.c:621
[#4](https://code.videolan.org/videolan/vlc/-/issues/4)  0x080f2274 in DecodeVideo__ffmpeg (p_dec=0x888bd30, pp_block=0xb25c43b4) at video.c:504
[#5](https://code.videolan.org/videolan/vlc/-/issues/5)  0x080a4255 in DecoderDecode (p_dec=0x888bd30, p_block=0x888b3f8) at src/input/decoder.c:663
[#6](https://code.videolan.org/videolan/vlc/-/issues/6)  0x080a5845 in DecoderThread (p_dec=0x888bd30) at src/input/decoder.c:488
[#7](https://code.videolan.org/videolan/vlc/-/issues/7)  0xb7f892bb in start_thread () from /lib/tls/libpthread.so.0
[#8](https://code.videolan.org/videolan/vlc/-/issues/8)  0xb7c4000e in clone () from /lib/tls/libc.so.6

it seems ffmpeg is the one crashing here...