Conference bgsdev::multimedia_services

482.0. "Audio,Vedio Syncronization problem, V2.0 & unix 3.2C" by QCAV02::NRHEGDE (T&E or R&D !?) Fri Jan 31 1997 04:36

Hi !

Configuration :

DEC ALPHA 250 4/266, 128 MB RAM, 1x 1GB HARD DISK, 
FULL VIDEO SUPREME MULTIMEDIA CARD, ZLXPE3 GRAPHICS ADAPTER
Panasonic video camera connected to the multimedia card (video card)

DEC UNIX V3.2C , DEC MULTIMEDIA SERVICES V2.0 software.

When using the 'alphavcr' utility of the multimedia services and using
the 'record option' to record a video session from the video camera,the
following is observed :

a) there is a synchronisation gap between the video and sound i.e. when a
person speaks, there is a time delay between the lip movements and the
sound.

b) suddenly after about 30 seconds of recording, the moving picture in the
alphavcr display window freezes and one can hear a lot of hard disk activity
going on. Recording is not possible after that and the only solution is to
exit alphavcr. 

While playing back the files generated the same synchronisation problem
and in case (b) the picture freezing problem exists.

Is there some way to overcome these problem? Please advise as soon as possible.


I have played .MPG files using alphavcr.
What happens is - it plays the file, but near the end quite a few frames
are not played (depending on the total no. of frames - about 10%). No sound
is played in .MPG ( I am not very sure whether .MPG accomodates sound also)
by alphavcr. For that matter mpegplay and xanim is also same (sound).

As far as I remember I can play the .AU files with decsound, though I have
not tried jerking the decsound window.

The files generated by alphavcr with Full video supreme and Panasonic video
camera while recording is not in .MPG format , they may be in some sort
of dynamic .JPG (jpeg) format. The example videos with sound which alphavcr
can play back (in /usr/examples/mme/sample_data/avi) have .AVI extension 
but are not in the MS-WINDOWS .AVI format (I can not play them in MS-WINDOWS).

Please note that Dec multimedia services is of version 2.0 and the display
is Truecolor type (ZLxpe3 graphics adapter 1280x1024 resolution). Prior
to multimedia services v2.0 it was not possible to get the alphavcr working
with trucolor display type.


 I am novice to multimedia things. Can any body tell what should I do to 
resolve this problem?

 Thx & Regards
Nagaraj Hegde