[MEncoder-users] Aspect ratio change during MPEG-TS not detected (bug?)
Ruud van der Linden / FluxxNet.nl
ruud at fluxxnet.nl
Mon Feb 23 14:28:51 CET 2009
I'm working on a system that records an MPEG-TS stream (MPEG2) directly
from DVB-T, and uses mencoder to transcode it directly to MPEG4/H.264.
They seem to totally ignore any change and only use the first aspect
ratio found in the stream (if the stream starts at 4:3, it will maintain
that ratio always). Options like dsize,aspect,scale,autoaspect all seem
to have no effect on the way mencoder handles the mid-stream change.
However, I'm running into one problem: mencoder or its filters do not
handle aspect ratio changes correctly (mplayer and vlc do).
I would like to have one of the following results in output-file:
1) an mp4 (h264) file which contains the same aspect ratio change
instructions as the original mpeg-ts, if that is possible (don't know
2) a permanent 4:3-aspect file (e.g. 768x576) which letterboxes the 16:9
You can find a sample movie at this location (the beginning is corrupted
as it is a dd'ed part from the file):
When starting the transcode, it mentions:
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
Halfway (at the aspect ratio change) it mentions:
VDec: vo config request - 704 x 576 (preferred colorspace: Planar
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
But I don't see it actually prescaling at all. By the way, this was
tested with the current svn version of mencoder as well as with older
versions, all show the same behaviour.
I hope someone can come up with a fix for this bug. Thanks in advance
With kind regards,
Ruud van der Linden
More information about the MEncoder-users