[Speex-dev] Speex and RTP

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Mon Feb 5 17:24:39 PST 2007

> 1. Missing definition of M_PI if it's undefined (and it is on this
> platform)

Just fixed it in svn. Thanks.

> 2. In speex_resampler_process_int, the compliler can't determine the
> value of *in_len and *out_len at compile time and thus determine the
> size of the x and y arrays.

Yes, it's still an annoyance that MS can't figure out how to write a C99
compiler :-(  I'll (eventually) "fix" that by falling back on alloca()
and/or malloc().

> I've resolved these issues locally with quick and obvious hacks and when
> I get a chance I'll integrate your resampler into some code of ours and
> see how it goes. We're currently using a combination of my own
> resampling code (for simple cases) and the Windows ACM Library (which
> yields poor results, no filtering as far as I can tell) so your
> development of this functionality is quite timely for us (thanks :) ).

I wouldn't be surprised if it was yet another library that thinks linear
interpolation is OK (hint to all audio library developers it NOT). One
of the main reason why I wrote this resampler is that I'm really tired
of hearing aliasing coming from linear interpolation resamplers. Anyway,
let me know how it works for you and if there's anything else that needs
to be fixed.


> Cheers,
> Dave
>> -----Original Message-----
>> From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca] 
>> Sent: Monday, 5 February 2007 9:27 PM
>> To: David Hogan
>> Cc: Randy Schefiele; speex-dev at xiph.org
>> Subject: Re: [Speex-dev] Speex and RTP
>>> I believe there is new resampling functionality in the 
>> speex svn head,
>>> although I haven't tested it yet. You might also want to check out
>>> 'Secret Rabbit Code' for your resampling.
>> Yes, I've just been working on a resampler recently. Its 
>> changing a lot,
>> but it's now usable. I'd actually be quite happy to have some feedback
>> on it.
>> 	Jean-Marc
>>> Hope this helps.
>>> Dave
>>> ________________________________
>>> 	From: speex-dev-bounces at xiph.org
>>> [mailto:speex-dev-bounces at xiph.org] On Behalf Of Randy Schefiele
>>> 	Sent: Saturday, 3 February 2007 7:12 AM
>>> 	To: speex-dev at xiph.org
>>> 	Subject: [Speex-dev] Speex and RTP
>>> 	Hi -
>>> 	I am currently developing a RTSP/RTP/SDP solution to stream
>>> Speex encoded data.  Using my current source, I have successfully
>>> streamed u-law and PCM encoded audio but have been 
>> unsuccessful thus far
>>> with Speex.
>>> 	Because of some constraints of my system, I am encoding audio at
>>> 11.025kHz.  I am still using the 160 samples per frame 
>> which makes my
>>> frame size 28 bytes.  I have successfully written the SDP needed to
>>> describe the Speex stream but I haven't found a player that 
>> will play
>>> the stream.  I could be doing something wrong, but does 
>> anyone know of
>>> any players that can play RTP Speex streams so I can be sure that my
>>> solution is incorrect?
>>> 	Also, I have looked over the draft RFC of the Speex RTP payload
>>> and I was curious to know if, because I am not using a 
>> standard sample
>>> rate, my solution will work.  In the draft RFC (and the 
>> Speex manual for
>>> that matter) it always refers to Speex frames containing 
>> 20ms of audio.
>>> In my case, a Speex frame actually contains roughly 14.5 seconds of
>>> audio.  Am I going to need to hack the Speex encoder to 
>> make my frames
>>> be 20ms in order for the RTP to successfully play?
>>> 	Any advice/help anyone can give would be greatly appreciated.
>>> 	Thanks!
>>> 	Randy
>>> ________________________________
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