[Speex-dev] Re: One bug in the SVN and rtp wrapper issue

lianghu xu lianghu.xu at gmail.com
Tue Nov 21 18:49:07 PST 2006


if the new draft in the manual is used.  I  don't find how to tell the
decoder which mode(NB/WB/UWB) is used
in the encoder.  The RTP header don't contain the mode field and I don't
find the mode information in the
coded frame either.

Does this mean we have to use NB decoder in all cases?

Lianghu

On 11/22/06, Jean-Marc Valin <jean-marc.valin at usherbrooke.ca> wrote:
>
>
>
> lianghu xu wrote:
> > In a word, I don't what's the standard of speex payload format.
> > The file doc/rtp.txt is for what?  Is it not for rtp payload?
> > I find that rtp.txt is more detail that draft02.txt
> >
> > Which rtp docment should be followed?
> > Anyone else has written the RTP wrapper already?
>
> Oh, I see. doc/rtp.txt was a very, very early draft. See the manual for
> a newer one.
>
>         Jean-Marc
>
> > Lianghu
> >
> > On 11/22/06, *Jean-Marc Valin* <jean-marc.valin at usherbrooke.ca
> > <mailto:jean-marc.valin at usherbrooke.ca>> wrote:
> >
> >     > 1) First, I think there is a bug in  libspeex/lsp.c  line 512.
> >     >
> >     > /* hard limit ak's to +/- 32767 */
> >     >       if (a < -32767) a =32767;   // This line should be changed
> to if
> >     > (a < -32767) a = -32767;
> >     >       if (a > 32767) a = 32767;
> >     >       ak[j-1] = (short)a;
> >
> >     Oops. Thanks for pointing that out. It's fixed in svn.
> >
> >     > 2) About the RTP wrapper for VoIP
> >     >
> >     > I'd like to use the payload format defined in the SVN document
> rtp.txt
> >     > as below.
> >     >
> >     > What I'm worry about is the interoperability with other
> >     implementations.
> >     >
> >     > What's your opinion on that?
> >
> >     Can you summarize what the issue is?
> >
> >             Jean-Marc
> >
> >     > Best Regards,
> >     >
> >     > Lianghu
> >     >
> >     >
> >     > //************************from the SVN /doc/rtp.txt begin
> >     > *************************************//
> >     > The Speex RTP payload is defined as a header, followed by any
> >     number of
> >     > requests to the remote encoder and all encoded speech frames.
> >     >
> >     > +--------+----------+----------------+
> >     > | Header | Requests | Speech data... |
> >     > +--------+----------+----------------+
> >     >
> >     > The header contains only the number of frames sent
> >     > encoded in 6 bits
> >     >
> >     >  0 1 2 3 4 5
> >     > +-+-+-+-+-+-+
> >     > | NB frames |
> >     > +-+-+-+-+-+-+
> >     >
> >     > There can be any number of requests of the form
> >     >
> >     >  0 1 2 3 4 5 6 7 0 1
> >     > +-+-+-+-+-+-+-+-+-+-+
> >     > |R| ReqID | ReqVal  |
> >     > +-+-+-+-+-+-+-+-+-+-+
> >     >
> >     > where R is 1 when a request is following and 0 when there is no
> more
> >     > request. Each request (if R=1) is composed of a 4-bit request ID
> >     (ReqID) and
> >     > a 5-bit value (ReqVal)
> >     >
> >     > Possible values for ReqID are:
> >     >  0: REQ_PERSIST   ReqVal=1 for persistent requests/mode selection,
> >     >                   0 otherwise
> >     >  1: PERSIST_ACK   Acknowledge a REQ_PERSIST from the other end,
> >     >                   ReqVal equals the value received
> >     >  2: MODE          Choose the encoder mode directly
> >     >  3: QUALITY       Choose the encoder quality
> >     >  4: VBR           Set VBR on (ReqVal=1) or off (ReqVal=2)
> >     >  5: VBR_QUALITY   Set the encoder quality for VBR mode
> >     >  6: LOW_MODE      Set the encoder mode for low-band (wideband
> only)
> >     >  7: HIGH_MODE     Set the encoder mode for high-band (wideband
> only)
> >     >
> >     > All requests should be considered at the receiver as a suggestion
> and
> >     > compliance is not mandatory. The PERSIST_ACK should be sent upon
> >     receiving a
> >     > REQ_PERSIST request to indicate that the request has been
> received.
> >     >
> >     > The speech data part contains speech frames one after the other.
> >     The size of
> >     > the encoded frames can be found since the mode is directly encoded
> >     into each
> >     > frame.
> >     >
> >     > For example, a frame where we request VBR to be on with quality 8
> >     and we
> >     > transmit two frames encoded at 8.35 kbps (167 bits/frame) will be:
> >     >
> >     >  0               1               2               3
> >     >  0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |   NB=2    |1|ReqID=2| ReqVal=0|1|ReqID=3|ReqVal=8 |0| frame 1 |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 1                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 1                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 1                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 1                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 1                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |end|                     frame 2                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 2                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 2                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 2                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |                         frame 2                               |
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     > |    end frame 2    |P|P|P|P|P|P|
> >     > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> >     >
> >     > //************************from the SVN /doc/rtp.txt end
> >     > *************************************//
> >
> >
>
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