does VLC have support of ulaw/alaw with static payload type

[pjain01]

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

[hillbilly1980]

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.

[pjain01]

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.

[Rémi Denis-Courmont]

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).

[kk23400]

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

[Rémi Denis-Courmont]

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

[kk23400]

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

[Rémi Denis-Courmont]

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

[kk23400]

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

[Rémi Denis-Courmont]

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

[kk23400]

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.

[kk23400]

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.

[kk23400]

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.

[kk23400]

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.

[Rémi Denis-Courmont]

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