How to dump a stream faster than real time...

Marco Ballesio gibrovacco at
Sun Mar 20 21:32:34 PDT 2011


sorry for the late reply, but I'm always one week in the future..

Being interested in RAI stuff as well, I found your question quite
interesting. Maybe you've already understood what's the point (or
maybe not) btw I'm writing here my outcomes not to completely waste
the time spent so far ;) .

First of all, I checked with wireshark what are the changes in RTSP
packets and especially into the SDP contents when setting/not setting
the -bandwidth parameter with mplayer.

following the above steps it has been easy to note that the
SET_PARAMETER method (as for RFC2326, par. 10.9) is used to control
the server bandwidth.

Now, a simple grep SET_PARAMETER in the GStreamer sources shows many results in:

- gstrtspdefs.c (plugins-base)
- rtspreal.c (plugins-ugly)
- OT: many results in pulseaudio sources (!!)

In the first case, SET_PARAMETERS appears to be used only for logging
purposes, while in the second it's used only for a single purpose
(setting the url).. bad luck.

It should anyway be quite simple to modify gstrtspsrc to behave as
expected when using the connection_speed property, which FWIW appears
not to be used anywhere. Is this a bug or a work-in-progress feature?
In the first case I have an half-cooked patch that should do the
trick, but would the mplayer way (using SET_PARAMETERS instead of an
header in the SETUP message) be the right one?


On Mon, Mar 14, 2011 at 5:54 PM, andrea <sarkiaponius at> wrote:
> On Mon, 2011-03-14 at 16:26 +0200, Stefan Kost wrote:
>> On 12.03.2011 17:59, andrea wrote:
>> > Hi,
>> >
>> > I try again since my previous message was ignored. If I'm asking the
>> > wrong mailing list just let me know.
>> Nobody is ignoring your message. It could just mean that no one has an
>> answer.
> Sorry, I wouldn't mean to be unpolite.
>> > I'm using a command line like the following to download old episodes of
>> > some audio programmes of italian broadcasting company (Rai).
>> >
>> > gst-launch-0.10 gstrtpsession bandwidth=40000000 rtspsrc
>> > location=rtsp:// connection-speed=2100000 ! decodebin2 ! wavenc !filesink location=prova.wav
>> Why do you create an extra rtspsession? It won't be used. Both plugins
>> have several examples in the manual.
> I tried this way because of the bandwidth property of gstrtspsession.
> Indeed it makes no difference, as you said.
> It seems really hard to find a solution. That's a pity, because
> gstreamer seems the only way to access RTSP streams through
> TelecomItalia routers. Actually, I found that ffmper does it too, but it
> has no option to control the speed nor the bandwidth.
> Best regards and many thanks.
>> Stefan
>> > Actually, the episodes are not real streams, but just RealAudio files
>> > that you can only access via RTSP.
>> >
>> > The above command line works perfectly but, despite the "bandwidth" and
>> > "connection-speed" options, to download the file it simply takes exactly
>> > the duration of the episode (they usually last 45 minutes each).
>> > I've using mplayer too, to do the same, and it has a wonderful option
>> > "-bandwidth" which, with a value, say, of 4000000, just lets you
>> > download the same file above in less than one minute!
>> >
>> > I'm wondering if there is some way to do the same with some gstreamer
>> > pipeline. I mean, some way to accelerate the download just as mplayer
>> > does. It would be very very nice because mplayer has problems with some
>> > ADSL router and some networks here in Italy, while gstreamer does not.
>> > Best regards.
>> >
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