Subsequent entry time calculations use blockalign value to determine
number of frames per chunk, and blockalign == 1 is then most unlikely to result
in reasonable values (which also aligns with "spec").

Rename some defines and move some itesm to *.c files. Add more items to internal
subsection.

... since recent code also seeks around to obtain required data
from avi index.

Push mode seeking uses same index data as pull mode, and stores
offset to data in chunk, whereas push mode operates in chunks,
and as such needs offset consistently corresponding to chunk headers.
Also fix determining best matching stream for incoming newsegment event,
as well as setting some stream state accordingly.

In particular, fixes non-flushing seek.

The audio packets in AVI are generally muxed ~0.5s before the
corresponding video packet. This changes causes downstream to only
receive packets with roughly corresponding timestamps.

Add some debug in the DISCONT handling code.
When we receive a DISCONT in push mode, mark all streams as DISCONT.

Make sure we reset the demuxer correctly wrt parsing the index.
Don't leak pending seek events.
Rename some methods to reflect what they do and to avoid confusion with similar
method names.
Try to make the seeking threadsafe by protecting the setup code with a lock.
Make sure we post errors when a seek fails.

seek_event -> seg_event
event_seek -> seek_event

When we have not parsed any indexes yet, we don't know the length of the streams
and we must take the length given in the avih as a fallback.
Avoid some typechecking.

When we receive an UNEXPECTED from a stream, move to the next stream and only go
EOS when all streams are EOS. When selecting a stream to push, ignore streams
that went EOS.

Fixes #607949

for some streams we might fail to fetch the index offsets. Don't try to parse
NULL indexes in those cases.

When we are in push mode, we can encounter RIFF and idx tags in the data chunk
when we are dealing with ODML files. In these cases, simply skip the chunks and
continue streaming instead of going EOS.

Add some debug in the DISCONT handling code.
When we receive a DISCONT in push mode, mark all streams as DISCONT.

When we receive a flush event on the sinkpad, reset the EOS state and the
flowreturn of all streams. Also mark the streams with a DISCONT.

Rename the seek_event variable to seg_event because it really contains the
newsegment event that needs to be pushed.

when we have not yet parsed the indexes (in push mode, for example) use
the duration as given in the avih header instead of -1.

Be safer on sscanf by limiting string format sizes.
Remove useless parameter and use g_strndup.

Greatly simplify the IDIT chunk handling by using sscanf
instead of 'manually' parsing. Also replaces strncasecmp and
is_alpha/is_digit with glib versions.

Fix typo in last commit.

Parses and post date tags contained in IDIT chunks.

Fixes #503582

Fix up a few debug messages so that it's clearer what they mean.

Set the current_entry to 0 (instead of -1) in push mode so that we correctly
calculate the current frame number and timestamp.

Add some more debug info and fic the duration debug.

Use segment_full so that we can pass the applied rate to the segment values. We
will change the applied rate when we implement skip mode.

total_idx is always evaluated.

This ensures we actually push out everything

It will only actually pull the junk blobs from upstream if the memdump
level is activated