Get rid of 0.5s latency when playing audio over Bluetooth with A2DP

Question

As described in the title I experience a half a second delay when playing audio over Bluetooth with A2DP.
This makes watching movies not possible as the sound is not synchronised with the video.

I'm not sure if the delay is caused by the Bluetooth standard, the A2PD protocol, the A2DP implementation on Ubuntu 12.04, or the Belkin Z73 Bluetooth Receiver.

Anyways, is this a normal lag? Is there a way to play audio over Bluetooth without any noticeable latency?

Answer 1

I get similar problem occasionally, irrespective of the player used. Mine is a Nokia BH-503 Bluetooth Stereo Headphone with MSI CR400 laptop and Ubuntu 11.10. I happened to come across a workaround which you can try.

• Start the video playback.
• Go to Sound Settings > Hardware.
• Select the Bluetooth device.
• Then in Settings for the Selected Device drop-down, switch to Telephony Duplex (HSP/HFP) profile, then switch back to High Fidelity Playback (A2DP).

Answer 2

No, this is not normal but I've had a similar problem occasionally with my Altec Lansing iMT525 Bluetooth Speakers. Something similar in concept to Sri's answer almost always works for me, and I need to do it only once per connect.

Auto-switching Bluetooth profiles to re-initialize PulseAudio

If you're looking for a culprit, I'd look at Ubuntu's sound system, PulseAudio first, and then your bluetooth receiver. Try this:

• First, delete and re-pair your Bluetooth device.

• Then, copy and paste the below into a .sh file in your home directory, say /home/brillout/pabluezswitch.sh:

  #!/bin/bash
  
  BLUEZCARD=`pactl list cards short | egrep -o bluez.*[[:space:]]`
  pactl set-card-profile $BLUEZCARD a2dp
  pactl set-card-profile $BLUEZCARD hsp
  pactl set-card-profile $BLUEZCARD a2dp
  

• Make the file executable by opening a terminal and typing chmod +x ~/pabluezswitch.sh

• Go to Settings...Keyboard...Shortcuts, and create a custom shortcut; name it whatever you want, with the command as /home/brillout/pabluezswitch.sh (substitute appropriate username in path!). Click Apply, and then click on the right where it says Disabled to set up a keyboard shortcut to execute the script.

What this does is force the PulseAudio system to resynchronize the audio being sent to your headset/speakers by switching profiles from ad2p -> hsp -> a2dp, thus hopefully getting rid of any latency.

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Whenever you connect and notice the lag, you should press the keyboard shortcut chosen above to attempt to fix the latency -- hopefully it works for you!

Answer 3

individuals who are having this problem Please view this website: http://projectzeorymer.wordpress.com/2011/09/01/ubuntu-how-to-connect-nokia-bh-503-bluetooth-headset-to-your-pc/ to see a pic of what you need to download.

Download the bluetooth manager and use it to manipulate the settings of the headset. Set the sound settings to High Fidelity Playback (A2DP) and then go in sound settings.

Answer 4

Adaptive differential pulse code modulation involves a look-ahead type compressing algorithm where information cannot be transmitted before the encoder has had a chance to examine several bytes of forthcoming info. Hence, data has to stack up in the encoder, and there is an inherent time shift between the streams entering and leaving the encoder. Long ago, I did a study of data network delays to determine the feasibility of voice-over-data telephony (what is now VoIP). I think I concluded that ADPCM-style compression/encoding would introduce too much delay. I think to overcome this Bluetooth-delay problem, one might need a non-compressing type of audio encoding which should have lower latency.