Audio latency in Windows Mobile

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How could you be sure that it's not audio device performance? Audio
device burst level could be checked using 'device test' of
pjsystest[1]. Also, please try making call using lightweight codec
such as G711, as CPU load spikes may disturb audio clock. The audio
latency section in FAQ, you've mentioned before, may describe more.

---
[1] http://trac.pjsip.org/repos/wiki/Testing_Audio_Device_with_pjsystest
---

BR,
nanang


On Fri, Dec 11, 2009 at 1:05 AM, Nuno Costa <nuno.costa at wit-software.com> wrote:
> Hi,
>
> I've been taking a deeper look into the media flow implementation and I
> think the problem for the high latency might be in the network management
> (maybe at the device level).
> Beyond the JB summary from the previous message, check the following logs:
>
> 17:49:30.000?? strm01D5B674? Jitter buffer empty (prefetch=40)
> 17:49:30.000???? ec01CF73F0? Underflow, buf_cnt=0, will generate 1 frame
> 17:49:30.000?? Master/sound? 140 samples reduced, buf_cnt=815
> 17:49:30.000?? Master/sound? Buffer size adjusted from 955 to 815
> (eff_cnt=689)
> 17:49:31.000???? ec01CF73F0? Underflow, buf_cnt=0, will generate 1 frame
> 17:49:31.000?? strm01D5B674? jb updated(2), prefetch=40, size=49
> 17:49:31.000?? strm01D5B674? jb updated(2), prefetch=40, size=41
> 17:49:31.000?? Master/sound? 143 samples reduced, buf_cnt=832
> 17:49:31.000?? Master/sound? Buffer size adjusted from 975 to 832
> (eff_cnt=689)
> 17:49:32.000???? ec01CF73F0? Underflow, buf_cnt=0, will generate 1 frame
> 17:49:32.000?? strm01D5B674? Jitter buffer empty (prefetch=40)
> 17:49:32.000?? strm01D5B674? Jitter buffer empty (prefetch=40)
> 17:49:32.000?? strm01D5B674? jb updated(2), prefetch=40, size=49
> 17:49:33.000?? Master/sound? 141 samples reduced, buf_cnt=851
> 17:49:33.000?? Master/sound? Buffer size adjusted from 992 to 851
> (eff_cnt=676)
> 17:49:33.000?? Master/sound? 140 samples reduced, buf_cnt=711
> 17:49:33.000?? Master/sound? Buffer size adjusted from 851 to 711
> (eff_cnt=676)
> 17:49:33.000?? strm01D5B674? Jitter buffer empty (prefetch=40)
> 17:49:33.000???? ec01CF73F0? Underflow, buf_cnt=0, will generate 1 frame
> 17:49:34.000?? Master/sound? 136 samples reduced, buf_cnt=735
> 17:49:34.000?? Master/sound? Buffer size adjusted from 871 to 735
> (eff_cnt=667)
> 17:49:34.000?? strm01D5B674? jb updated(2), prefetch=40, size=41
>
> The jitter buffer is becoming many times empty which means that the audio
> latency experienced is not related with the audio device performance.
> I've rechecked the network latency and it is very low. Could it be a network
> device issue?
>
> Have anyone experienced this before?
> Any ideas on a possible solution?
>
> Nanang: do you have any suggestion, looking to the JB summary?
>
> Thank you very much for your support.
>
> Cheers,
> Nuno Costa
>
>
> On 09-12-2009 19:31, Nuno Costa wrote:
>
> Nanang,
>
> Thank you very much for your reply.
> The JB summary below is from a test call:
>
> ? JB summary:
> ??? size=44 prefetch=40
> ??? delay (min/max/avg/dev)=20/500/362/128 ms
> ??? burst (min/max/avg/dev)=2/98/33/29 frames
> ??? lost=86 discard=781 empty=427
>
> The average delay (362ms) is very high and has impact on the overall
> latency.
> Any clue on how to optimize this value?
>
> Best regards,
> Nuno Costa
>
>
> On 09-12-2009 17:41, Nanang Izzuddin wrote:
>
> Hi Nuno,
>
> Problem behind ticket #783 is high latency issue on WM :)
>
> Agree, 300ms different is quite strange/high. It is usually useful to
> examine the JB statistics at the end of call (printed by
> pjmedia_jbuf_destroy()), e.g: if JB was used to get full, clock-drift
> or high burst of audio device might take place.
>
> BR,
> nanang
>
>
> On Thu, Dec 3, 2009 at 5:30 AM,  <ncosta at wit-software.com> wrote:
>
>
> Hi all,
>
> I've developed an application using PJSIP for Microsoft Windows Mobile 6.x
> devices and I've been testing it on some devices.
>
> Unfortunately the audio latency is very high on both devices (Samsung
> Omnia II and LG LM730). Values are typically as high as 700ms, measured
> from end-to-end.
>
> I've checked your wiki:
> http://trac.pjsip.org/repos/wiki/FAQ#audio-latency
>
> And also this ticket:
> http://trac.pjsip.org/repos/ticket/783
>
> I've done several tests adjusting the parameters but results haven't
> changed. Running 'pjsystest', the average value is 400ms for both devices.
>
> Has anyone faced this problem already?
>
> I've done these tests on a local network with a low network latency so I
> do not quite understand the 300ms difference between the end-to-end test
> and pjsystest.
>
> Any clue on the problem behind ticket #783?
>
> Thanks!
>
> Best regards,
> Nuno Costa
>
>
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>
>
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>
>
> --
> =========================================
> Nuno Costa
> Senior Engineer
> WIT Software S.A.
> Coimbra, Lisboa, Leiria, Porto (Portugal)
> San Jose (California, USA)
> Phone : +351 239 801030
> Mobile: +351 91 9821825
> Email : nuno.costa at wit-software.com
> Web: http://www.wit-software.com
> =========================================
>
> --
> =========================================
> Nuno Costa
> Senior Engineer
> WIT Software S.A.
> Coimbra, Lisboa, Leiria, Porto (Portugal)
> San Jose (California, USA)
> Phone : +351 239 801030
> Mobile: +351 91 9821825
> Email : nuno.costa at wit-software.com
> Web: http://www.wit-software.com
> =========================================



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