def retimestamp_tags_inplace(f, fu):
flv = FLV(f)
offset = None
for tag in flv.iter_tags():
if offset is None and is_nonheader_media(tag):
offset = tag.timestamp
log.debug("Determined the offset to be %d", offset)
# optimise for offset == 0, which in case of inplace updating is a noop
if offset is not None and offset != 0:
fu.seek(tag.offset + 4, os.SEEK_SET)
fu.write(make_si32_extended(tag.timestamp - offset))
def retimestamp_tags_inplace(f, fu):
flv = FLV(f)
offset = None
for tag in flv.iter_tags():
if offset is None and is_nonheader_media(tag):
offset = tag.timestamp
log.debug("Determined the offset to be %d", offset)
# optimise for offset == 0, which in case of inplace updating is a noop
if offset is not None and offset != 0:
fu.seek(tag.offset + 4, os.SEEK_SET)
fu.write(make_si32_extended(tag.timestamp - offset))
def output_offset_tag(fi, fo, tag, offset):
new_timestamp = tag.timestamp - offset
# do not offset non-media and media header
if not is_nonheader_media(tag):
new_timestamp = tag.timestamp
# write the FLV tag value
fo.write(make_ui8(class_to_tag[tag.__class__]))
# the tag size remains unchanged
fo.write(make_ui24(tag.size))
# wirte the new timestamp
fo.write(make_si32_extended(new_timestamp))
# seek inside the input file
# seek position: tag offset + tag (1) + size (3) + timestamp (4)
fi.seek(tag.offset + 8, os.SEEK_SET)
# copy the tag content to the output file
# content size: tag size + stream ID (3) + previous tag size (4)
fo.write(fi.read(tag.size + 7))
def output_offset_tag(fi, fo, tag, offset):
new_timestamp = tag.timestamp - offset
# do not offset non-media and media header
if not is_nonheader_media(tag):
new_timestamp = tag.timestamp
# write the FLV tag value
fo.write(make_ui8(class_to_tag[tag.__class__]))
# the tag size remains unchanged
fo.write(make_ui24(tag.size))
# wirte the new timestamp
fo.write(make_si32_extended(new_timestamp))
# seek inside the input file
# seek position: tag offset + tag (1) + size (3) + timestamp (4)
fi.seek(tag.offset + 8, os.SEEK_SET)
# copy the tag content to the output file
# content size: tag size + stream ID (3) + previous tag size (4)
fo.write(fi.read(tag.size + 7))
