The VideoLAN Forums

Hi All,
I am trying to stream an audio file (.mp3) using ulaw/alaw codecs with rtp. I am giving the following command line option in GUI
:sout=#transcode{acodec=ulaw,ab=64,scale=1,channels=1,ar=8000}:rtp{dst=my ip-address,port-audio=1234}

This I am doing with unicast IP address. The VLC version I am using is 0.9.2 on windows XP

There are two observation I have:
1) On ethereal, I am seeing rtp stream with payload type 96(dynamic payload type) which I thought should be 0 for PCMU and 8(static) for PCMA. Am I seeing the right audio stream with ulaw codec? Why this audio stream is not using the static payload type for PCMU i.e 0 for PCMU and 8 for PCMA.
2) Not able to able to play this particular stream on the other side using VLC.
- Does VLC have the support of playing PCMU stream?

Following are few more questions I have
- Also Does VLC support rtp with ulaw/alaw codec?
- and if yes what is the right command for this ?
- does VLA have the support for ulaw/alaw in case of unicast(I had seen some of the forums mentioning that ulaw/alaw support is available in case of multicast only)

Thanks
Pjain

Same boat here. I'm trying to save an rtp stream of ulaw to file time that's easier to play and convert. Any help would be appreciated.

I got my problem resolved, But for that I had to visit the code for debugging the actual cause of the problem.
VLC doen't stream the PCMU layer if you have a the audio file in some other formats(like I was using mp3 file for sending out PCMU stream thinking that VLC will do the transcoding , but somehow it wasn't. )I had to take an original PCMU audio file with mono , 8000KHz(sampling rate) .After this I could easily send out the audio stream(using PCMU and static payload 0) and also could easily listen it on the receiving VLC.

VLC can transcode to PCMU/PCMA from any audio codec. What VLC cannot do (properly) is resampling and downmixing. In other words, it will work with any 8kHz mono input (but not necessarily G.711).

I got a file with H.264/G.711 stream, and VLC 0.9.9(windows) can play this file normally.
I have some questions :
(1) Can I stream output this file to http or another file(with the same codec H.264/G.711).If yes, How to do it.
I try to use VLC to output this stream, but only video output, no audio.

(2) According to the modules/mux/mpeg/ts.c, vlc only support mpga, mp3, a52,lpcm,dts,mp4a, but no ulaw/alaw?

(3) What is the number of ulaw's i_stream_type and i_stream_id? And alaw ?

Thanks a lot !

Best regards,

J

µlaw nad alaw are only supported on top of RTP, not on top of MPEG-TS.

Thanks for your reply, could you tell me what's the number of ulaw's i_stream_type and i_stream_id? How about alaw ?
Thank you very much.

J

I have no ideas what you're on about. VLC follows RFC3551.

I am thinking about if it is possible to add ulaw/alaw on MPEG-TS.
That's why I need i_stream_type and i_stream_id of ulaw/alaw.
Any advice would be appreciated. Thanks a lot.

J

No G.711 is TS is not implemented as far as I know. I don't even know if it's been specified.

What's the stream type of alaw in PMT ? Mpga is 0x03 or 0x04 (depend on i_rate >= 3200 or not). I need some help to implement alaw on ts by myself, thanks a lot.

I guess the stream id of alaw in PES is 0xC0. and I set stream type of alaw from 0x00 to 0xFF,
but none of them is alaw. What's the stream id and stream type of alaw? Thank you very much.

Is there anyone can give me some suggestion? I am trying to add alaw/ulaw on TS stream, but what's the audio stream type and stream id of alaw/ulaw. Is it possible to add alaw/ulaw on TS stream ? I am willing to add this function on VLC by myself and share it to anyone, but I need some help first. Thanks a lot.

Excuse me. Is it illegal or impossible to add alaw/ulaw on TS stream, or just nobody knows how to do it ? Where can I get more information about it ? Any advice would be appreciated. Thanks a lot.

I don't know the TS standard, but VLC definitely does not implement G.711 inside Transport Stream.