[speex-dev] Speex settings and jitter

[John Hayes]

Right - and I deal with that on the receiver end based on an approximation
of sender's and receiver's responsiveness - the minimum latency I've been
able to get into the system is about 150 ms. Of that, jitter buffering is
about 40-100ms. I'd love to figure out how to get that down without killing
myself on thread switching or Win32 kernel calls, but ms has to actually
implement the DSBCAPS_CTRLPOSITIONNOTIFY capability in direct sound capture
...

John

> -----Original Message-----
> From: owner-speex-dev at xiph.org [mailto:owner-speex-dev at xiph.org]On
> Behalf Of Allen Drennan
> Sent: Tuesday, May 20, 2003 11:18 AM
> To: speex-dev at xiph.org
> Subject: RE: [speex-dev] Speex settings and jitter
>
>
> In my experience most of the jitter related issues are because people are
> using too small of audio buffer sizes that match the framing size
> of Speex -
> particularly in Windows.  This isn't a problem with Speex, but as a
> programmer you should collect and append a few frames to match the size of
> your output audio frame buffer before attempting to play the sound.
>
> -----Original Message-----
> From: owner-speex-dev at xiph.org [mailto:owner-speex-dev at xiph.org] On Behalf
> Of John Hayes
> Sent: Tuesday, May 20, 2003 11:12 AM
> To: speex-dev at xiph.org
> Subject: RE: [speex-dev] Speex settings and jitter
>
> The audio frame speex generates sounds pretty terrible most of
> the time, and
> I don't use it for jitter correction instead I just use it for dropped
> packets - so I usually drop the late packet. It sounds acceptable
> as long as
> I drop less than 5% of traffic (dropping 2 in a row makes a bad
> robot noise,
> so I reset the stream in that case). The good news is that on an
> unsaturated
> DSL line jitter and packet loss are basically 0.[1]
>
> In my experience dropping a packet without decoding NULL or
> without playing
> the gap packet make a really bad tick.
>
> John
>
> [1] The bad news is on a saturated DSL connection - it's
> basically unusable
> without a second of jitter buffering.
>
> > -----Original Message-----
> > From: owner-speex-dev at xiph.org [mailto:owner-speex-dev at xiph.org]On
> > Behalf Of Chris Flerackers
> > Sent: Tuesday, May 20, 2003 9:05 AM
> > To: speex-dev at xiph.org
> > Subject: [speex-dev] Speex settings and jitter
> >
> >
> > Hi,
> >
> > Is there are document where the interaction between all the
> configuration
> > options of speex is explained?
> > Speex seems to have CBR, VBR and ABR. You can also use SPEEX_SET_QUALITY
> > (SPEEX_SET_VBR_QUALITY) and SPEEX_SET_BITRATE which I suppose
> can't be set
> > at the same time. Is there a list of possible combinations somewhere?
> >
> > I also have another question related to jitter. To minimize jitter, you
> > usually need to make the audio
> > shorter and longer and preferably while keeping it sound smooth.
> > What is the
> > best way to do this
> > with speex? I saw that you can pass NULL to the decode function
> > to generate
> > an audio frame which
> > might be used to make the audio longer. Will speex always generate a
> > "fluent" audio stream (without ticks, ...)
> > when inserting these NULLs. And is dropping a packet a viable
> way to make
> > the audio shorter?
> >
> > Best regards,
> > Chris
>
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