[MPlayer-dev-eng] Architect: follow mode

[Sam Liddicott]

I'm slowly modifying mplayer for a follow mode as part of my 
introduction to it's internals, and I think it advisable to consult here 
from time to time so I don't make any major errors.

I want a mode where if mplayer is playing a file and the file grows 
while playing mplayer doesn't stop early.

I figure the first stage is for mplayer to know when it has such a 
stream that is follow-able.

I reckon around line 467 of libmpdemux/open.c we see STREAMTYPE_FILE - I 
guess these are the only grow-able seek-able streams anyway.

Now a few things refer to stream->end_pos from time to time, but most 
things cache it like:

demuxer->movi_end=stream->end_pos;

So I guess periodically on of the demuxer functions is going to want to 
call a new stream function to get a new end_pos, using:
len-lseek(f,0,SEEK_END); lseek(f,0,SEEK_SET);

If I'm not too far out then I'll start to look for a suitable demuxer 
function into which I can put the check-if-stream-has-grown code.  I 
would think in the read-blocks but only if so long has passed since last 
time, or so much K has been read or we are near what we think is the 
end; ftell() should be cheap enough?

What say you guys?


Later I would like for it to also record in the stream struct whether or 
not the file is observed to be growing;
for if the file has been observed to grow recently (or maybe if file 
mod_time is less than 20 seconds?) at the point we seem to reach the 
real end of file we might wait a bit to see if it does grow a bit more 
and also if we are doing a user-seek we can choose not to quit beause 
the file is quite likely to grow.

Even later-later I want to implement stretchable-circular buffers for 
tivo like buffering, but much later.