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Support files with multiple mdat atoms. #19

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Support files with multiple mdat atoms. #19

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41 changes: 26 additions & 15 deletions qtfaststart/processor.py
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Original file line number Diff line number Diff line change
Expand Up @@ -193,40 +193,51 @@ def process(infilename, outfilename, limit=float('inf'), to_end=False,
# Get the top level atom index
index = get_index(datastream)

mdat_pos = 999999
mdat_pos_first = -1
mdat_pos_last = -1
free_size = 0

# Get position of first and last mdat atom(s)
for atom in index:
if atom.name == "mdat":
if (atom.position < mdat_pos_first or mdat_pos_first < 0):
mdat_pos_first = atom.position
if (atom.position > mdat_pos_last or mdat_pos_last < 0):
mdat_pos_last = atom.position

if mdat_pos_first < 0:
# No mdat atom found
msg = "No mdat atom found."
log.error(msg)
raise FastStartSetupError(msg)

# Make sure moov occurs AFTER mdat, otherwise no need to run!
for atom in index:
# The atoms are guaranteed to exist from get_index above!
if atom.name == "moov":
moov_atom = atom
moov_pos = atom.position
elif atom.name == "mdat":
mdat_pos = atom.position
elif atom.name == "free" and atom.position < mdat_pos and cleanup:
elif atom.name == "free" and atom.position < mdat_pos_first and cleanup:
# This free atom is before the mdat!
free_size += atom.size
log.info("Removing free atom at %d (%d bytes)" %
(atom.position, atom.size))
elif (atom.name == "\x00\x00\x00\x00" and atom.position < mdat_pos):
elif (atom.name == "\x00\x00\x00\x00" and atom.position < mdat_pos_first):
# This is some strange zero atom with incorrect size
free_size += 8
log.info("Removing strange zero atom at %s (8 bytes)" %
atom.position)

# Offset to shift positions
offset = - free_size
if moov_pos < mdat_pos:
if to_end:
# moov is in the wrong place, shift by moov size
offset -= moov_atom.size
else:
if not to_end:
# moov is in the wrong place, shift by moov size
offset += moov_atom.size

if offset == 0:
is_setup = False
if (moov_pos < mdat_pos_last and to_end):
# moov is in the wrong place, shift by moov size
offset -= moov_atom.size
elif (moov_pos > mdat_pos_first and not to_end):
# moov is in the wrong place, shift by moov size
offset += moov_atom.size
elif free_size == 0:
# No free atoms to process and moov is correct, we are done!
msg = "This file appears to already be setup!"
log.error(msg)
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