avi: Improve non-interleaved detection

Additional fixes by Nigel Touati-Evans <nigel.touatievans@gmail.com>.

Check the index for streams with a time drift of 2s or a buffer drift
of 64MB.

Bug-Id: 666
CC: libav-stable@libav.org
Sample-Id: yet-another-broken-interleaved-avi.avi

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Diego Biurrun <diego@biurrun.de>
(cherry picked from commit 9d599e3f6e61438772d8cddd6c9b7c495251f51e)
Signed-off-by: Reinhard Tartler <siretart@tauware.de>
pcm-dvd: Fix 20bit decoding

Increment the pointer as needed.

Bug-Id: 592

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
(cherry picked from commit 9880a0d4b131ef36694d62f78060350a81f08b80)
Signed-off-by: Reinhard Tartler <siretart@tauware.de>