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

[Roberto Togni]

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.

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.

Ciao,
 Roberto
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