small spikes(click/pop) of audio during media playback

asked 2024-10-16 00:34:05 +0000

v911
1 ●1

updated 2024-10-16 01:05:38 +0000

Trying to figure out why during playback the audio appears to have clicks/pops/spikes and when exported to WAV file they are not audible.

Experimented with several laptops and trying to figure out if this is something to do with the RTP player in wireshark or not? As I do not know how the RTP packets are converted to WAV format if there is any kind of transcoding etc hide the click/pops.

I suspect these clicks don't exist ... I exported to as RAW and used audio tool to decode original PCM file 8K sampling 16 bit uLaw. I am presuming this export is not transcoded and simply the output of the RTP stream and there were no clicks there.

I also noticed the clicks/pops seem to happen on the side of the call where there is no audio. The Audio playing side of the call doesn't seem to have issues.

I have also tested with faster laptops as well and same issue exists as well so I suspect its not hardware issue btu simply with RTP player.

Hoping someone can confirm and that there is a fix for this ? V

answered 2024-10-16 12:16:55 +0000

Jaap

13742 ●711 ●115

updated 2024-10-16 13:41:13 +0000

cmaynard

11115 ●11 ●317 ●165 https://www.igt.com/

The thing you need to be aware of is that media playback depends not only on the audio samples, but on the timely availability of these samples. Saving the audio samples in a WAV file and playing them back provides all samples to the media player at the same time. Therefore the media player never runs out of samples to play and the audio is 'smooth', as in, not interrupted by missing audio samples.

Now if you look at RTP this is not necessarily the case. The network packets may come in delayed, causing the RTP player to miss the samples it needs to play. This is where the jitter buffer comes in to help out. It gives some leeway in the arrival time of RTP packets and provides for a smooth, albeit delayed, playback.

This delayed playback may not be an issue, but quickly becomes one if for instance it stretches beyond 150 ms in a phone call.

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agreed On these captures there is no packet loss, high latency in fact all well bellow 20 ms and same with jitter buffer (ptime is 20ms and its steady on the analysis window with minimal skew .... basically its as good as a call can get on G.711 ulaw codec). In fact after some complaints on from some of my fellow engineers about popping sounds I made a reference test calls which had no end user issue. The popping/click sounds was there and again to be clear the artifacts are not on the side playing the audio but on the other speaker (meaning if I am hearing the user 1 conversation on Left side headset/speaker and user 2 is right side speaker/headset, when user1 is speaking on left side and user 2 is silent, the pops/clicks would happen on the user2 side that has no audio ...(more)

v911 ( 2024-10-16 16:53:29 +0000 )edit

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