[Asterisk-Users] Re: Audio flutter on OH323 output?

[Michael Manousos]

Tony Mountifield wrote:
> In article <d6ft7h$dsd$1 at softins.clara.co.uk>, I wrote:
> 
>>In article <428B6974.7080305 at inaccessnetworks.com>,
>>Michael Manousos <manousos at inaccessnetworks.com> wrote:
>>
>>>Can you get an ethereal trace on a call with that problem?
>>>Run an RTP analysis on the captured stream (Tools Menu) and save
>>>the contents of the RTP packets in audio files. Then check if
>>>the playback of these files is normal or not.
>>
>>Aha, sounds like Ethereal has even more clever features - I didn't
>>know it could do that.
>>
>>Fortunately, I've been running a continuous tcpdump capture on the
>>Asterisk box of the traffic between it and the switch. I'll see
>>what Ethereal thinks of it.
> 


Hi Tony,

> 
> Hi Michael,
> 
> I've now done some RTP analysis of affected streams, and have found that
> the times when we get the audio flutter correspond with parts of the
> analysis showing repeated packets in the RTP stream. This only happens
> on the outgoing stream; the incoming stream from the switch is perfect.
> 
> When a packet is repeated, it is identical to the previous and occurs
> about 7 to 14 microsec after, as if something in the software has decided
> to send the packet twice in immediate succession.


This seems as a bug in OpenH323, but also as a bug in the switch's RTP
implementation. Normally, the remote RTP stack should reject the
duplicate packet. Of course this does not cancel the need to fix the
bug in OpenH323. I'll prepare a version which compiles with the latest
code of OpenH323/Pwlib. You can try it and see if the problem is still
there.

> 
> I've pasted below an extract from the CVS file saved from the RTP
> stream analysis. I also saved the payload (pity it converts it to uLaw
> instead of saving it in the stream's native format) and listened to it
> to confirm the periods of distortion.
> 
> I would assume the problem is somewhere in the depths of openh323, but
> any pointers in the right direction would be appreciated!
> 
> Cheers
> Tony


Regards,
Michael.


> 
> Here is the CSV extract:
> 
> Packet,Sequence,Delay (s),Jitter (s),Marker,Status,Date,Length
> 144209,17353,0.020000,0.000003,,[ Ok ],05/17/2005 17:05:48.420,214
> 144225,17354,0.020006,0.000003,,[ Ok ],05/17/2005 17:05:48.440,214
> 144226,17354,0.000007,0.000003,,Wrong sequence nr.,05/17/2005 17:05:48.440,214
> 144244,17355,0.019987,0.000004,,[ Ok ],05/17/2005 17:05:48.460,214
> 144260,17356,0.019998,0.000004,,[ Ok ],05/17/2005 17:05:48.480,214
> 144261,17356,0.000008,0.000004,,Wrong sequence nr.,05/17/2005 17:05:48.480,214
> 144276,17357,0.019991,0.000004,,[ Ok ],05/17/2005 17:05:48.500,214
> 144296,17358,0.019992,0.000004,,[ Ok ],05/17/2005 17:05:48.520,214
> 144298,17358,0.000009,0.000005,,Wrong sequence nr.,05/17/2005 17:05:48.520,214
> 144313,17359,0.019990,0.000005,,[ Ok ],05/17/2005 17:05:48.540,214
> 144329,17360,0.020000,0.000005,,[ Ok ],05/17/2005 17:05:48.560,214
> 144349,17361,0.019992,0.000005,,[ Ok ],05/17/2005 17:05:48.580,214
> 144368,17362,0.020003,0.000005,,[ Ok ],05/17/2005 17:05:48.600,214
> 144369,17362,0.000006,0.000005,,Wrong sequence nr.,05/17/2005 17:05:48.600,214
> 144383,17363,0.019990,0.000005,,[ Ok ],05/17/2005 17:05:48.620,214
> 144401,17364,0.019995,0.000005,,[ Ok ],05/17/2005 17:05:48.640,214
> 144417,17365,0.020001,0.000005,,[ Ok ],05/17/2005 17:05:48.660,214
> 144432,17366,0.019994,0.000005,,[ Ok ],05/17/2005 17:05:48.680,214
> 144452,17367,0.019997,0.000005,,[ Ok ],05/17/2005 17:05:48.700,214
> 144469,17368,0.020002,0.000005,,[ Ok ],05/17/2005 17:05:48.720,214
> 144486,17369,0.019998,0.000005,,[ Ok ],05/17/2005 17:05:48.740,214
> 144487,17369,0.000008,0.000005,,Wrong sequence nr.,05/17/2005 17:05:48.740,214
> 144506,17370,0.019985,0.000005,,[ Ok ],05/17/2005 17:05:48.760,214
> 144523,17371,0.019999,0.000005,,[ Ok ],05/17/2005 17:05:48.780,214
> 144540,17372,0.020005,0.000005,,[ Ok ],05/17/2005 17:05:48.800,214
> 144559,17373,0.019992,0.000005,,[ Ok ],05/17/2005 17:05:48.820,214
> 144560,17373,0.000008,0.000005,,Wrong sequence nr.,05/17/2005 17:05:48.820,214
> 144576,17374,0.019988,0.000006,,[ Ok ],05/17/2005 17:05:48.840,214
> 144577,17374,0.000007,0.000006,,Wrong sequence nr.,05/17/2005 17:05:48.840,214
> 144592,17375,0.019992,0.000006,,[ Ok ],05/17/2005 17:05:48.860,214
> 144593,17375,0.000008,0.000006,,Wrong sequence nr.,05/17/2005 17:05:48.860,214
> 144610,17376,0.019987,0.000007,,[ Ok ],05/17/2005 17:05:48.880,214
> 144627,17377,0.019997,0.000006,,[ Ok ],05/17/2005 17:05:48.900,214
> 144628,17377,0.000008,0.000006,,Wrong sequence nr.,05/17/2005 17:05:48.900,214
> 144642,17378,0.019989,0.000007,,[ Ok ],05/17/2005 17:05:48.920,214
> 144661,17379,0.019997,0.000007,,[ Ok ],05/17/2005 17:05:48.940,214
> 144678,17380,0.020004,0.000006,,[ Ok ],05/17/2005 17:05:48.960,214
> 144679,17380,0.000009,0.000007,,Wrong sequence nr.,05/17/2005 17:05:48.960,214
> 144695,17381,0.019988,0.000007,,[ Ok ],05/17/2005 17:05:48.980,214
> 144696,17381,0.000007,0.000007,,Wrong sequence nr.,05/17/2005 17:05:48.980,214
> 144713,17382,0.019982,0.000008,,[ Ok ],05/17/2005 17:05:49.000,214
> 144732,17383,0.020002,0.000007,,[ Ok ],05/17/2005 17:05:49.020,214
> 144733,17383,0.000008,0.000007,,Wrong sequence nr.,05/17/2005 17:05:49.020,214
> 144747,17384,0.019989,0.000008,,[ Ok ],05/17/2005 17:05:49.040,214
> 144768,17385,0.020000,0.000007,,[ Ok ],05/17/2005 17:05:49.060,214
> 144769,17385,0.000007,0.000007,,Wrong sequence nr.,05/17/2005 17:05:49.060,214
> 144784,17386,0.019986,0.000007,,[ Ok ],05/17/2005 17:05:49.080,214
> 144801,17387,0.020001,0.000007,,[ Ok ],05/17/2005 17:05:49.100,214
> 144802,17387,0.000008,0.000007,,Wrong sequence nr.,05/17/2005 17:05:49.100,214
> 144820,17388,0.019987,0.000007,,[ Ok ],05/17/2005 17:05:49.120,214
> 144836,17389,0.020001,0.000007,,[ Ok ],05/17/2005 17:05:49.140,214
> 144852,17390,0.019994,0.000007,,[ Ok ],05/17/2005 17:05:49.160,214
> 144854,17390,0.000008,0.000007,,Wrong sequence nr.,05/17/2005 17:05:49.160,214
> 144872,17391,0.019990,0.000007,,[ Ok ],05/17/2005 17:05:49.180,214
> 144891,17392,0.019995,0.000007,,[ Ok ],05/17/2005 17:05:49.200,214
> 144907,17393,0.019999,0.000007,,[ Ok ],05/17/2005 17:05:49.220,214
> 144926,17394,0.019996,0.000007,,[ Ok ],05/17/2005 17:05:49.240,214
> 144942,17395,0.020001,0.000006,,[ Ok ],05/17/2005 17:05:49.260,214
> 144958,17396,0.019993,0.000006,,[ Ok ],05/17/2005 17:05:49.280,214
> 144976,17397,0.019999,0.000006,,[ Ok ],05/17/2005 17:05:49.300,214
> 144992,17398,0.019995,0.000006,,[ Ok ],05/17/2005 17:05:49.320,214
> 145008,17399,0.019999,0.000006,,[ Ok ],05/17/2005 17:05:49.340,214
> 145026,17400,0.019996,0.000005,,[ Ok ],05/17/2005 17:05:49.360,214
> 145042,17401,0.019999,0.000005,,[ Ok ],05/17/2005 17:05:49.380,214
> 145059,17402,0.020001,0.000005,,[ Ok ],05/17/2005 17:05:49.400,214
> 145079,17403,0.019993,0.000005,,[ Ok ],05/17/2005 17:05:49.420,214
> 145097,17404,0.020003,0.000005,,[ Ok ],05/17/2005 17:05:49.440,214
> 145098,17404,0.000007,0.000005,,Wrong sequence nr.,05/17/2005 17:05:49.440,214
> 145113,17405,0.019987,0.000006,,[ Ok ],05/17/2005 17:05:49.460,214
> 145131,17406,0.019996,0.000005,,[ Ok ],05/17/2005 17:05:49.480,214
> 145147,17407,0.019997,0.000005,,[ Ok ],05/17/2005 17:05:49.500,214
> 145163,17408,0.020002,0.000005,,[ Ok ],05/17/2005 17:05:49.520,214
> 145182,17409,0.019993,0.000005,,[ Ok ],05/17/2005 17:05:49.540,214
> 145198,17410,0.020000,0.000005,,[ Ok ],05/17/2005 17:05:49.560,214
> 145215,17411,0.019997,0.000005,,[ Ok ],05/17/2005 17:05:49.580,214
> 145235,17412,0.019998,0.000005,,[ Ok ],05/17/2005 17:05:49.600,214
> 145251,17413,0.019999,0.000004,,[ Ok ],05/17/2005 17:05:49.620,214
> 145267,17414,0.019996,0.000004,,[ Ok ],05/17/2005 17:05:49.640,214
> 145287,17415,0.019999,0.000004,,[ Ok ],05/17/2005 17:05:49.660,214
> 145303,17416,0.019996,0.000004,,[ Ok ],05/17/2005 17:05:49.680,214
> 145320,17417,0.020000,0.000004,,[ Ok ],05/17/2005 17:05:49.700,214
> 145321,17417,0.000008,0.000004,,Wrong sequence nr.,05/17/2005 17:05:49.700,214
> 145341,17418,0.019989,0.000005,,[ Ok ],05/17/2005 17:05:49.720,214
> 145342,17418,0.000007,0.000005,,Wrong sequence nr.,05/17/2005 17:05:49.720,214
> 145358,17419,0.019992,0.000005,,[ Ok ],05/17/2005 17:05:49.740,214
> 145373,17420,0.019998,0.000005,,[ Ok ],05/17/2005 17:05:49.760,214
> 145392,17421,0.019995,0.000005,,[ Ok ],05/17/2005 17:05:49.780,214
> 145409,17422,0.019996,0.000005,,[ Ok ],05/17/2005 17:05:49.800,214
> 145425,17423,0.019999,0.000004,,[ Ok ],05/17/2005 17:05:49.819,214
> 145444,17424,0.019995,0.000005,,[ Ok ],05/17/2005 17:05:49.839,214
> 145461,17425,0.020002,0.000004,,[ Ok ],05/17/2005 17:05:49.859,214
> 145462,17425,0.000008,0.000005,,Wrong sequence nr.,05/17/2005 17:05:49.860,214
> 145476,17426,0.019986,0.000005,,[ Ok ],05/17/2005 17:05:49.879,214
> 145497,17427,0.020000,0.000005,,[ Ok ],05/17/2005 17:05:49.899,214
> 145498,17427,0.000008,0.000005,,Wrong sequence nr.,05/17/2005 17:05:49.899,214
> 145513,17428,0.019987,0.000006,,[ Ok ],05/17/2005 17:05:49.919,214
> 145531,17429,0.019998,0.000005,,[ Ok ],05/17/2005 17:05:49.939,214
> 145532,17429,0.000009,0.000006,,Wrong sequence nr.,05/17/2005 17:05:49.939,214
> 145550,17430,0.019986,0.000006,,[ Ok ],05/17/2005 17:05:49.959,214
> 145569,17431,0.020006,0.000006,,[ Ok ],05/17/2005 17:05:49.979,214
> 145570,17431,0.000008,0.000006,,Wrong sequence nr.,05/17/2005 17:05:49.979,214
> 145584,17432,0.019983,0.000007,,[ Ok ],05/17/2005 17:05:49.999,214
> 145605,17433,0.020002,0.000007,,[ Ok ],05/17/2005 17:05:50.019,214
> 145606,17433,0.000008,0.000007,,Wrong sequence nr.,05/17/2005 17:05:50.019,214
> 145621,17434,0.019984,0.000007,,[ Ok ],05/17/2005 17:05:50.039,214
> 145638,17435,0.020003,0.000007,,[ Ok ],05/17/2005 17:05:50.059,214
> 145639,17435,0.000008,0.000007,,Wrong sequence nr.,05/17/2005 17:05:50.059,214
> 145656,17436,0.019984,0.000008,,[ Ok ],05/17/2005 17:05:50.079,214
> 145673,17437,0.019997,0.000007,,[ Ok ],05/17/2005 17:05:50.099,214
> 145689,17438,0.019998,0.000007,,[ Ok ],05/17/2005 17:05:50.119,214
> 145708,17439,0.019999,0.000007,,[ Ok ],05/17/2005 17:05:50.139,214
> 145725,17440,0.019997,0.000006,,[ Ok ],05/17/2005 17:05:50.159,214