Re: debconf5 - videos of the talks and BOFs available
On Mon, 25 Jul 2005 21:19:21 +0200, Ben Hutchings <ben@decadentplace.org.uk> wrote:
[Cross-posted to debconf5-video now that I'm subscribed to it; perhaps
this should move away from debconf5-event.]
On Mon, 2005-07-25 at 13:16 +0200, Herman Robak wrote:
Recoding back to a higher resolution is a no-no, when avoidable.
Is it avoidable? I suppose it would be possible to scale down to
352x288/240, but I wonder how that would look.
It will look quite fine on a TV set. A little blurry compared
to full-resolution DVD, but not worse than VHS.
If I recall
correctly, DVD players can handle 352x288, too. I don't remember what
the exact constraints were on the audio. I suspect 32 KHz is out of
spec, and that 44.1 KHz is required.
I believe only 48 kHz MP2 is allowed (which is odd, because DVD players
are required to play CDs too).
48 kHz is fine; the original DV is 48 kHz PCM.
> Assuming that the GOP length is the same as what mencoder calls
> "keyframe interval", it claims the maximum is 132,
I think the maximum for unconstrained MPEG is even higher,
but you can't expect that to work on a standalone DVD player!
The mencoder manual page says that "[f]or a strict MPEG-1/2/4 compliance
this would have to be <=132."
Compliant is not the same as constrained. VCD and DVD are rather
narrow subsets of the MPEG1/2 standards.
If you want to be sure that the video is playable on all DVD
players, the GOP should not be larger than 12 for PAL and 15 for
NTSC.
The Wikipedia page <http://en.wikipedia.org/wiki/MPEG-2#MPEG-2_on_DVD>
says 15 and 18 respectively. Where do you get those lower figures from?
You are right. I probably confused the GOP sizes of 1080i HDV
(and possibly VCD, too).
--
Herman Robak
--
To unsubscribe, send mail to debconf5-event-unsubscribe@lists.debconf.org.
Reply to: