Can't hear LPCM via http

[vane.vlc]

Hi,

I'm posting here because I think I've found a bug in the libraries vlc use. Correct me if i'm wrong.
I'm trying to play LPCM audio via an http URL. I have an http server called rygel (http://live.gnome.org/Rygel) that transcodes whatever audio file to LPCM and serves the content via http.
The problem is that vlc doesn't play the url.
I also use XBMC, which uses the same libraries as vlc (I think) and the libraries (libavcodec, libavformat or libavutil) cannot determine the content and it suposses that is MP3, so I hear strange noises, because it tries to decode LPCM as MP3.
Instead, if I try to play it with totem, I can hear it ok.

I didn't find this issue in the forum, do you know something about it?

Thanks in advance,

Vanesa.

[Jean-Baptiste Kempf]

please share a link to a sample.

[vane.vlc]

I can't provide a link because the link is for a local network.
I can show you how to make an example:

First: If you have some files in mp3 in your computer, you have to install Rygel (http://live.gnome.org/Rygel), which is a UPnP server, and share these files. Rygel offers the content in MP3, LPCM and original content (which is MP3 also if the files are mp3) via http.
These step is the trick: you have to obtain the LPCM url from rygel. For this you can use gupnp-tools (http://www.gupnp.org/downloads/gupnp-tools-0.8.1) and extract the DIDL-Lite document, which contains the urls.
Third: Try to play the http url in vlc.

I know these is not trivial, if I found some internet http url with LPCM content, I'll share it, but I supposse this will be difficult. Tell me if you need some more explanation.

Thanks and regards,

Vanesa.

[Rémi Denis-Courmont]

LPCM is a codec, not a file format. I don't see how you can stream LPCM directly over HTTP. So no wonder that media players do not understand what is going on.

[vane.vlc]

You can stream LPCM over HTTP by using the MIME type: "audio/L16;channels=2;rate=4800", for example.

[Rémi Denis-Courmont]

audio/L16 is plain 16-bits PCM. But that's an RTP payload format, not a "normal" MIME type. It is not meant for general (non-RTP) use.

[vane.vlc]

Yes, It is an RTP payload format but it has a MIME type and there is no reason you can't stream it over HTTP. There are some devices that can play LPCM over HTTP (like PS3) and it is used in DLNA/UPnP standards.
I was just surprised vlc can't play it. That's all.
Also, I'm thinking this could be a ffmpeg (and not vlc) issue.
Thanks for your answers.