"Movie offset: 2 seconds", revisited

[DCK21]

Hi all,

Sorry for this very old topic, but I have not found a satisfactory
explanation yet. Any help much appreciated.

Sorry again if I miss forum (basic/advance); I post here as I understand it fits better.

I am currently making some comparison tests with different
muxers and demuxers. Have not find any solid thing about, any
hint mostly welcomed. Will post findings (BTW which forum?
this _as conclusion might be interesting here_ or VCD/SVCD
encoding & authoring as more general topics covered)

Through the way, I found out the default DVD2SVCD configuracion of
Movie offset: 2 seconds, used within bbMPEG.

Intriged, I searched and researched the forums (it is somehow complicated looking for 2 seconds gives nothing, looking for Movie offset bbMPEG returns hundred of postings _at least one per log ;-)
the Q&As, etc.

Found many references, mostly all related to DVD player syncing problem resolution, but answers seem to me unsatisfactory.

As far as I understand, the movie offset marks how many seconds of
the stream will be discarded and not really be muxed (with default
DVD2SVCD settings, my test movies lose 2 seconds at the beginning
and the file size shortens ...) but, from the forums,

a) most people confuse stream delay with movie offset
b) some people confirm that movie offset solves their syncing
problems; some confirm contrarywise.

In any case, I cannot understand the given reasons for the 2 seconds
movie offset solving the syncing problem. As example, somebody said

quote (author name purposely not written)
"2s was really the default and it makes sense to leave it at this setting. The drive in a DVD-player needs some time to speed up just like a PC-drive, and starting the audio and videostreams immediately would make the initial seconds prone to stuttering and even some unwanted desynchronization between audio and video"

If you cut the initial 2 seconds from the original film ... you have
a file with another film, the same but shorter, that also would
require the DVD-player to speed up ... then, perhaps one should
cut another 2seconds ... and then again and again ...

So, I see no logical reason that backs up the need for keeping that
default 2 seconds movie offset. Perhaps it really solves sync
problems but I would appreciate a logical explantion linking the effect to this cause. I am unable to find one (mind locked?)

Again, help welcomed!

DCK21<-HAL

[DCK21]

Hi again,
later I thought that perhaps the video encoder includes some rubbish
at the beginning of the video stream that needs to be cut out. This
could justify the need for the 2 seconds cut.

Somebody with a player with sync problems without the cut could test
it, encoding with CEE and TMPGEnc, offset=0 and see if there is
any difference in sync?

Thanks again

DCK21<-HAL

[markrb]

I don't understand what you mean about 2 seconds being "cut" from the video. Nothing is cut, it's only delayed to let the player start to read at full speed.

Mark

[DCK21]

Hi markrb,

Thanks for your reply. Sorry but disagree, I have to insist:

from what I read and test, this is not a delay, but a cut; look:

a) what somebody says (could be wrong, of course):

http://forums.afterdawn.com/thread_view.cfm/15195

b) from Beyeler, bbMPEG history

http://members.cox.net/beyeler/bbnew.html

"Version 1.24 beta 13 11-Sep-00

[ non relevant things cut ]

Added a multiplexing option to only multiplex a specified time range (in seconds) from the input streams. The multiplexor still muxes the entire time range of the input streams, it only writes the portion within the time range to the output file. This can ...."

Speaks about the Start / End (/Size).

c) mrbass newbie reference, specifically:
(could also be wrong)

http://www.mrbass.org/dvd2svcd/1.0.8b1/dvd2svcd_newbieref.html#6

"bbMPEG

Movie offset seconds leave at default 2. . Don't adjust unless experiencing synch problems.
CD Overlap seconds CD#1 stops at 54:38 and CD#2 starts playing at 54:33 if 5 seconds is selected. Max overlap is 30 seconds.
Startup Delays (ms) Video 180 Audio 1 180 Audio 2 180.... leave as defaults"

Differenciates start up delays and Movie offset!

d) Testing (myself) with DVD2SVCD

Should you open the created .ini file for bbMPEG by DVD2SVCD,
there is a parameter called "muxStartTime", value = 2 (if you do
not change anything in DVD2SVCD settings). It corresponds to
Movie Offset in DVD2SVCD. Change that in DVD2SVCD, for example,
to 300. Open the .ini file. See muxStartTime value! Look to the
movie, you have lost the initial 300 seconds!

e) Testing (myself) with bbMPEG (beyeler one)

Open bbMPEG. Set Muxing Start/Stop/Size option to 60, 600, 999999.
Save parameters in mytest.ini. Open it. Look to muxStartTime.
Value = 60? Then ...

I could understand all badly, but ... ?

Thanks again,

DCK21<-HAL