Last coded block lost in packetizer

Packetizers cache the input block and give it back on the next call:

pf_packetize(1) = NULL;
pf_packetize(2) = 1;
pf_packetize(3) = 2;
/* block 3 is lost */

This can be noticed when playing audio (last packet is missing), or when muxing videos (the last frame is lost, frame count is reduced by 1).

21:00 < funman> i think the block should be returned immediately if it's a valid packet
21:01 < funman> why ? you don't need the next block to know if the previous one is valid
21:01 < nefrir> funman: for video, yes you need it
21:02 < nefrir> funman: nope, with mpeg 2 for instance, you now that you reach the end only when you see the next picture start code
21:02 < nefrir> same with mpeg 4 ASP and AVC(h264)
21:05 < nefrir> it's not that easy to fix, but I think that calling pf_packetizer(NULL) would be the right solution
21:05 < nefrir> and of course the packetizers need to be updated to handle that case

Note that for packetizer_copy this is a bit trickier: the length of blocks isn't known in input, and is computed by length(block[N]) = pts(block[N+1]) - pts(block[N]), so the length of the last block would be unknown.

That might point to broken demuxers though.