Choopy audio on low bandwith networks whereas Whatsapp works fine

JsBergbau commented 3 years ago

[x] I have searched open and closed issues for duplicates
[x ] I am submitting a bug report for existing functionality that does not work as intended
[ x] I have read https://github.com/signalapp/Signal-Android/wiki/Submitting-useful-bug-reports
[ x] This isn't a feature request or a discussion topic

Bug description

One phone has reduced bandwith to 32 KBit/s, the other phone is connected to 100 MBit/s Wifi. When calling a conversation is not possible because audio is very delayed and choppy. Calling with Whatsapp gives fine audio quality, no delay and no choppy audio. When both devices are in the same Wifi there is perfect call quality, so it is just a bandwith problem.

Steps to reproduce

Reduce bandwith to 32 KBit/s like the messaging option from Congstar provides on one phone or some Wifi-APs that support limiting speed of some devices.
Call with another phone which has enough bandwith
Try to have a clear conversation

Actual result: Audio is very delayed and choppy. Expected result: Clear audio quality as Whatsapp provides in that situation.

Screenshots

Device info

Device: Samsung Galaxy S10 Lite Android version: 11 Signal version: 5.2.3

Link to debug log

I don't think this needs a debug log. I've made this test already month before with same result, so it should be easy to reproduce.

fernando-villalba commented 3 years ago

There is a new setting "Use Less Data For Calls", you could try turning this on when on cellular network and see if this is still an issue?

JsBergbau commented 3 years ago

Sadly still very choppy when enabling "Use Less Data For Calls" for Wifi and cellular networks. Even when in addition turning this setting on the second phone which is in Wifi, there is a long delay, very choppy and no real call possible. Cross-checked again with Whatsapp. Good call quality despite reduced to 32 kbit/s.

sobsan commented 3 years ago

I have exactly the same issue. Calls are simlpy impossible. Again, with Whatsapp there is no problem at all.

I also tried the "use less data" option and also tried toggling the "relay calls over signal server" setting. I am also limited to 32kbit/s both up and downstream.

Is it technically possible to automatically reduce the call quality to adjust to the bandwidth available? Are there other ways to reduce data consumption (compress maybe)? I think there might be many with limited data bandwidth depening on your location. Also those with their monthly data consumed have a reduced speed for example of 64kbit/s down and 16kbit/s up. Personally I prefer having the ability to make calls over the quality of the call.

Flexmaen commented 2 years ago

Impossible calls here too, also very choppy, even with 10mbit/s. Might be a different problem than bandwith?

Classic298 commented 2 years ago

I too have choppy calls with huge lags and terrible audio quality. Unbearable. Even with a good internet connection!

tbertels commented 2 years ago

There's a post on Reddit suggesting Signal may be using TCP instead of UDP, which may explain these problems, is that a fact?

JsBergbau commented 2 years ago

It depends. Since some networks block almost all destination ports except 80 and 443 and especially UDP this approch can help user with user unfriendly configured firewalls.

have a tiny bit of VoIP experience, and I feel like it needs to drop down to a lower quality codec/bitrate in these situations to ensure packets get through on time.

Thats the main reason. Another codec should be selected that doesn't need so much bandwidth.

Classic298 commented 2 years ago

Okay idk what changes but for a few weeks now signal calls are working perfectly fine for me now. They really didn't in the past though

Does someone else sill have issues?

tbertels commented 2 years ago

No problem here.

JsBergbau commented 2 years ago

Problem still exists. It maybe a little bit better, but it is still impossible to do a useful Signal phonecall when one of the participant is limited to 32 KBit/s audio bandwidth whereas with Whatsapp there is enough call quality to have a real conversation.

alex-signal commented 2 years ago

The calling team has been doing a lot of work in this area. Please try altering the bandwidth options in call settings if you haven't already. Otherwise, please post some debug logs here after a call and I can forward them to the calling team.

tbertels commented 2 years ago

Indeed, there's an option in the Android version (not on Desktop) in Data and storage: Call: Use less data for calls: Never/Mobile data only/WiFi and mobile data. With the description "Using less data may improve calls on bad networks". This means that:

the call quality will be permanently lower even if the bandwidth is good
the user has to enable this setting, even though this can happen to any user

Is this option there only for testing purposes? E.g. to check if it's useful to implement automatic bandwidth throttling on bad connections?

JsBergbau commented 2 years ago

Using lower bandwidth on mobile data and Wifi is already enabled. Did an experiment. Download this App https://play.google.com/store/apps/details?id=com.nisargjhaveri.netspeed This shows current network traffic. When phoning via Whatsapp and Wifi it show mainly something between 1 and 2 kB/s when there is silence. When speaking, data rate goes up to 8 kB/s (4 kB/s each direction). With Signal there is already there ~17 kB/s. So Whatsapp seems to use much higher variable compression algorithm than Signal. 32 kBit/s is 4 kB/s, so Whatsapp stays within the limits given by mobile phone company with the reduced bandwidth of 32 kBit/s, calling works with good quality.

With Signal and mobile data datarate goes even up to 10 kB/s, so provider even gives higher speed than officially granted but still it is a lot too small for Signal.

Both phones have set the option to reduce bandwith for mobile data and wifi even though it should be sufficient to do that on the phone with reduced bandwith.

Flexmaen commented 2 years ago

Maybe it also depends on how the call is rooted. I had problems calling from Austria to Germany or New Zealand with Signal while Skype worked fine.

tbertels commented 2 years ago

Both phones have set the option to reduce bandwith for mobile data and wifi even though it should be sufficient to do that on the phone with reduced bandwith.

I wonder if Signal manages to enable this low bandwidth mode. If it doesn't, there should be a message in the debug log (In Settings > Help). The message should be either handleBandwidthModeUpdate: could not update bandwidth mode or Unable to update bandwidth mode on CallManager based on 1 and 2.

By the way, while Signal is supposed to use the Opus codec, there's no mention of it in the code, though AAC LC can be found.

I forgot to mention that there's a mention of a bitrate of 32000 (I'm guessing bit/s).

I didn't find what the bitrate is supposed to be in "reduced bandwidth mode".

JsBergbau commented 2 years ago

Sorry for the late reply. I've checked the log. The string bandwi can't be found. So I guess low bandwith mode seems to be enabled.

stale[bot] commented 2 years ago

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

JsBergbau commented 2 years ago

Problem still exists

cody-signal commented 2 years ago

@JsBergbau can you provide an updated debuglog? Preferably from the latest beta if possible.

JsBergbau commented 2 years ago

I have noticed another thing. Thats network traffic from Windows Ressource Monitor when Signal option is set to reduce bandwidth on phone (latest version from playstore 5.38.5) and using Signal Desktop (5.43.0) on PC. grafik

So with reduced bandwith about 4 KB/s data is flowing. Without reduced bandwith about 8 KB/s, so about double.

This example is when both in LAN, but thats not the point. This data is constantly flowing, even with silence. When speaking datarate is rarely higher. With Whatsapp with silence there is significant less data flowing than when speaking. So that is another point that should be investigated.

awaitlink commented 2 years ago

This data is constantly flowing, even with silence. When speaking datarate is rarely higher. With Whatsapp with silence there is significant less data flowing than when speaking. So that is another point that should be investigated.

I think this is because Signal uses a constant bit rate for calls to protect against side channel attacks that can reveal spoken words.

JsBergbau commented 2 years ago

So then only issue remains that bitrate is too high. Since signal uses opus codec and it has great compression for speech, there should be an option to lower bandwith even further. I've tried with opus with --bitrate 16 --hard-cbr and the quality was still way better than normal phone audio quality. Bitrate 16 is 2 KB/s and should work then on low bandwith networks. Maybe there would be even an adaptive bitrate possible as whatsapp seems to use. With Whatsapp you can sometimes hear audio quality change while in call.

stale[bot] commented 2 years ago

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

JsBergbau commented 2 years ago

Still an issue.

Totorrr commented 1 year ago

@cody-signal I guess this mostly needs a little testing, doesn't it? Would you actually benefit from a debug log here? I'm asking because my guess is that it would not help much, but I may be wrong.

Can you maybe try to lower the bitrate for calls, or even better, make the bitrate negotiable live so that it would be set to a lower setting in case of packet loss or excessive delay, and use higher bitrate otherwise?

kermem commented 1 year ago

Same issue here with calls, been going on for almost two years. No issues with WhatsApp and Telegram.

Enabling the "use less data for calls" option didn't help either.

Flexmaen commented 1 year ago

This is still open but I have to mention that I noticed that call quality significantly improved with some of the updates since then. For me Signal works fine for calling now.

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