gistfile1.txt

mkvinfo, first block:
| + SimpleBlock (key, track number 1, 1 frame(s), timecode 0.000s = 00:00:00.000) size 52689
|  + Frame with size 52681 hexdump 00 00 00 19 40 01 0c 01 ff ff 01 60 00 00 03 00
(...)

lldb, broken on first call to h264_mp4toannexb_filter:
(lldb) p buf_size
(int) $1 = 96
(lldb) x/96bx buf
0x7fff5fbfe9e0: 0x00 0xd6 0x81 0x04 0x01 0x00 0x00 0x00
0x7fff5fbfe9e8: 0x00 0xe6 0x8f 0x04 0x01 0x00 0x00 0x00
0x7fff5fbfe9f0: 0x00 0x6a 0x93 0x04 0x01 0x00 0x00 0x00
0x7fff5fbfe9f8: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
0x7fff5fbfea00: 0xf4 0x01 0x00 0x00 0x00 0x00 0x00 0x00
0x7fff5fbfea08: 0x00 0x00 0x00 0x00 0x05 0x00 0x00 0x00
0x7fff5fbfea10: 0xe8 0x03 0x00 0x00 0x00 0x00 0x00 0x00
0x7fff5fbfea18: 0x40 0x42 0x0f 0x00 0x00 0x00 0x00 0x00
0x7fff5fbfea20: 0x00 0x05 0x00 0x00 0x80 0x02 0x00 0x00
0x7fff5fbfea28: 0x80 0x02 0x00 0x00 0x00 0x00 0x00 0x00
0x7fff5fbfea30: 0x70 0xea 0xbf 0x5f 0xff 0x7f 0x00 0x00
0x7fff5fbfea38: 0xbb 0x65 0x18 0x02 0x01 0x00 0x00 0x00