mxfdec: Break out parts of mxf_read_header() into separate functions

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mxfdec: Parse PreviousPartition in mxf_seek_to_previous_partition()

Without this patch the demuxer can get stuck in a loop if PreviousPartition
points somewhere where there's no PartitionPack, or if klv_read_packet() syncs
back up to the current partition.

This should fix Ticket3278 properly and unbreak Ticket4040.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Revert "avformat/mxfdec: detect loops during header parsing"

This reverts commit 1c010fd035c1a14dc73827b84f21f593e969a5d6.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mxfdec: Merge last_partition and footer_partition

FooterPartition offset specified in RIP takes precedence over any value written
in PartitionPacks. This fixes the same issue f06f6da tries to fix without
introducing an extra variable.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mxfdec: Tighten RIP length bounds in mxf_read_random_index_pack()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Support raw dvdsub palette as stored on normal dvd's

This is how the palette is stored on dvd's. Currently
only xbmc passes the palette information to libavcodec
this way.
Check return value of avio_seek and avoid modifying state if it fails

The code still modifies state if the timestamp is not found. Not
sure exactly how to avoid that.
asf hacks
if av_read_packet returns AVERROR_IO, we are done. ffmpeg's codecs might or might not handle returning any completed demuxed packets correctly
added: Ticket #7187, TV Teletext support for DVB EBU Teletext streams
Don't accept mpegts PMT that isn't current
Don't reparse PMT unless it's version has changed
Read PID timestamps as well as PCR timestamps to find location in mpegts stream
Get stream durations using read_timestamp
changed: allow 4 second skew between streams in mov before attempting to seek
fixed: memleak in mpegts demuxer on some malformed (??) mpegts files with too large pes packets

at-visions sample file brokenStream.mpg
Speed up mpegts av_find_stream_info
dxva-h264 Fix dxva playback of streams that don't start with an I-Frame.
add public version of ff_read_frame_flush

We need this since we sometimes seek on the
input stream behind ffmpeg's back. After this
all data need to be flushed completely.