[vlc] Re: Dump streamed data

Fri Apr 9 14:20:20 CEST 2004

> On Fri, Apr 09, 2004, Philippe De Neve wrote :
>
> > Hi,
> >
> > I want to stream a file (I used MPEG-1 .m1v and MPEG-4 .mp4) from VLC to
VLC
> > using UDP or RTP. This works fine. The player VLC shows the clip
although
> > the first fraction of second the display is ugly (green) but fastly
> > recovers. No big problem so far.
>
> That's related to the  fact that VLC has to wait for  a complete I image
> before it can decode a proper image. That issue is related to the nature
> of yout MPEG4 stream, and cannot be avoided.
>
> > When I now want to dump this video clip to an output file I can choose
> > between  'raw data'  or not.  When I  do NOT  use 'dump  as raw  data'
> > a  file  is  contructed  but  it's  smaller  than  the  original  file
> > (1100219<->1055432 bytes). So some bytes where forgotten?The resulting
> > file is unplayable  so I checked the file binary  with ultraedit which
> > showed me that some (about 300)  "ff" bytes and some other stuff where
> > appended  at the  beginning of  the  file .They  do NOT  exist in  the
> > originating file.  There's probably  a relation with  the fact  VLC is
> > displaying the first 5 frames (or so) green.
> >
>
> That fact the file  size is not the same than the  original one could be
> explained by you  using a different muxer.  Having a bunch of  FF at the
> beginnig of  a file could be  normal with some muxers,  but shouldn't be
> related to the "green video" issue.  When you say you cannot re-read the
> stream, do you mean that VLC is unable to read it, or another software ?
>

Well, VLC is able to read it but I want VirtualDub to be able to read it so
I can convert it to raw yuv data for quality measurements. You say it is a
problem caused by using a different muxer. Is there a way to solve this  so
the dumped sequence is binary the same as the original streamed sequence?

> > Now  I  tried  to  dump  the  file as  "raw  data"  which  results  in
> > ....nothing. No file gets created and no data gets dumped?
>
> Strange.  No file  is generates,  or it  is deleted  at the  end of  the
> playback ? Copuld you send us the logs of this part (view->messages)
>

I was not able to reproduce this error. Probably something I did wrong! No
problem now!

> > This dumping capability is important for me (I want to measure quality
> > afterwards).  Can anybody  tell me  if this  is a  bug or  am I  doing
> > something very wrong?
>
> Well, since VLC doesn't re encode the stream if not told to, the quality
> the resulting  stream will  be the  same as  the original  one, excepted
> network related issues ;-)

Some packets of the stream will be dropped resulting in a degradation of
received quality. I want to check how VLC handles these errors and how much
the display quality will decrease.

>
> >
> >
> > wfr, Philipe De Neve
> >
> >
> > Some computer information:
> >
> >
> > Operating System   System Model
> > Windows XP Professional Service Pack 1 (build 2600)   No details
available
> >
> > Processor
> > 1,80 gigahertz AMD Athlon XP
> > 128 kilobyte primary memory cache
> > 256 kilobyte secondary memory cache   Board: K7VT2 2.00
> >
> > Main Circuit Board
> > Bus Clock: 133 megahertz
> > BIOS: American Megatrends Inc. P1.20 12/10/2002
> > Drives   Memory Modules c,d
> > 39,99 Gigabytes Usable Hard Drive Capacity
> > 14,63 Gigabytes Hard Drive Free Space
> >
> > SAMSUNG CD-ROM SC-152A
> > 3.5" format removeable media [Floppy drive]
> >
> > WDC WD400BB-60DGA0 [Hard drive] (40,02 GB) -- drive 0, s/n
WD-WCADK3849758,
> > rev 05.03E05, SMART Status: Healthy   512 Megabytes Installed Memory
> >
> > Slot '0' has 512 MB
> > Slot '1' is Empty
> > Slot '2' is Empty
> > Slot '3' is Empty
> >   Local Drive Volumes
> >
> > c: (on drive 0) 15,72 GB 3,16 GB free
> > e: (on drive 0) 10,48 GB 4,53 GB free
> > f: (on drive 0) 4,20 GB 2,21 GB free
> > g: (on drive 0) 9,60 GB 4,73 GB free
> >
> >
> >
> >
> >
> > *********************************************************
> >   ir. De Neve Philippe
> >   Ghent University
> >   Department of Information Technology (INTEC)
> >   Sint-Pietersnieuwstraat 41
> >   B-9000 Gent (Belgium)
> >   tel. :       +32 9 264 99 57
> >   e-mail :  philippe.deneve at intec.UGent.be
> > *********************************************************
> >
> > -- 
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> -- 
> $(echo "BigBen")
>
> Oui je quote, et alors ?
>
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