[MPlayer-users] real audio stream saved with option -dumpaudio cannot be played

[Roberto Togni]

On Tue, 14 Mar 2006 10:08:11 +0100 (MET)
"Othmar Frey" <othmarfrey at gmx.net> wrote:

> hi.
> 
> As I was a confused by the exact meaning of the
> two options -dumpstream and -dumpaudio
> I used -dumpaudio instead of -dumpstream to capture a real audio stream.
> (rtsp://206.165.150.203:554/encoder/DRS3.rm)
> mplayer fails to play the saved stream!!!
> 
> Now I have 2 questions:
> 1. How can I produce a *.wav or *.mp3 file from the data that I got with
>   mplayer -v -dumpaudio rtsp://206.165.150.203:554/encoder/DRS3.rm
>   (since i recorded a live stream I have no other choice than using
>   this data)
> 2. Could anybody explain what exactly I have recorded?

Probably useless data. The dump is a sequence of audio frames, with no
headers, timestamps, ...

>   The documentation says at one point
>   ( http://www.mplayerhq.hu/DOCS/HTML-single/en/MPlayer.html#streaming-save)
>   that the 2 options are equivalent for audio streams and at some other

That paragraph is totally wrong.

>   (the man page) it says:
>       -dumpaudio (MPlayer only)
>              Dumps raw compressed audio stream to ./stream.dump (useful with
> MPEG/AC3).
>   and
>   -dumpstream (MPlayer only)
>              Dumps the raw stream to ./stream.dump.  Useful when ripping
> from DVD or network.
>   Obviously, the 2 options are not equivalent at all.
> 

The manpage is right

> Could anybody shed some light on this?
> Thanks.
> 

-dumpstream and dumpaudio are not equivalent.
To save a network stream as-is you must use dumpstream. If you want an
uncompressed wave file you can use -ao pcm instead of dumpstream.

-dumpaudio saves the audio data without any information from the
original container, it's only useful with codecs like mp3 or aac where
you can play raw streams. It does not do any conversion, so the
original audio must be mp3 or aac to get valid output.

Except for some special situations, -dumpaudio and -dumpvideo are
useless for saving streams or extracting audio and video tracks.

Ciao,
 Roberto