[MPlayer-users] dumped realmedia stream not playable with realplayer

[Lev Givon]

Received from Roberto Togni on Tue, Jun 05, 2007 at 03:45:48PM EDT:
> On Tue, 5 Jun 2007 15:08:55 -0400
> Lev Givon <lev at columbia.edu> wrote:
> 
> > Received from Nico Sabbi on Tue, Jun 05, 2007 at 11:45:30AM EDT:
> > >  Lev Givon wrote:
> [...]
> > When I played the saved streams in mplayer, I noticed that mplayer prints
> > the line
> > 
> > demux_real: invalid chunksize! (0)
> > 
> > before it starts playing the video. I didn't notice this error when
> > playing a realmedia file that realplayer could also play. Examining the
> > saved stream files with a hex editor revealed that the file's DATA
> > chunk size and number of data packets (i.e., as described
> > http://wiki.multimedia.cx/index.php?title=RealMedia) were both 0; this
> > was not the case with realmedia files that realplayer could play.
> > 
> 
> That's because we don't know how many packets are in the stream when we
> start receiving it. The invalid chunksize should be something else,
> I'll try to look into it but I don't think that is the problem.
> 

Probably true..manually modifying the chunk size with a hex editor
prevented mplayer from printing the error but did not appease
realplayer.

> The main problem is that with -dumpstream MPlayer just write to disk
> what it's receiving from the net, and the data can't be altered in any
> way during the process. So MPlayer can't do any fixing on the file
> after it's dumped. I'm aware of some problems with playback of dumped
> realmedia, especially for live streams, but I don't know the details.
> 
> The proper way to dump a stream would be to use mencoder with -oac copy
> -ovc copy and a realmedia muxer, but atm we don't have a full-featured
> realmedia muxer. -dumpstream is really a debug option, that sometimes
> happens to be working also for other purposed, but it has some huge
> limitations.
> 
> I'm attaching two scripts I found on my disk, that "should" fix a
> dumped real stream: be warned that I didn't wrote them and never tested
> them, so I have no idea how/if they work. Also do a backup of your
> file, since at least one of them modifies the original file. If you
> feel brave enough to test them please report if they worked.
> 

They didn't work; judging from the script and a mailing list thread I
discovered that discussed them, it seems that the scripts were written
to fix files containing realaudio streams only.

> Ciao,
>  Roberto

						Grazi,
						L.G.


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