analog audio and sizzles for 0.5 s at the beginning

[hondansx]

Hi,

I use the analog output and at the beginning of every channel or recording I am getting sizzles for 0.5 s, which is annoying.
It looks like, this is an rasp problem. Is there any possibility to add some mute or delay in audioomx, so this sizzles/distortion are suppressed or not audible.

.

[MartenR]

This sounds like an firmware issue, probably due to high memory load at the startup. (This is because a programm on the videocore feeds a pwm modulator in realtime).
I have from the client side no influence on the playback, I suspect that even if I feed it with zeros, that the distortions may happen.

Well it is possible to mute the volume like the mute button does, but I do not like a solution were a problem is not solved but just hidden.
Given the current architecture of vomp is releatively hard to implement this reliable.
I would suggest, that you try to check, if it also happens with omxplayer and if yes contact the raspberry pi firmware developers.

Marten

[hondansx]

Yes this happens also with aplay. I tried different alsa settings but none were succesfull. It seems this is a known issue in firmware.

At the moment of writing a got an segfault with my client. Do not know if this can help in any way:

Code Select Expand


[ac3 @ 0x1901e40] Additional substreams not implemented. Update your Libav version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
[ac3 @ 0x1901e40] If you want to help, upload a sample of this file to ftp://upload.libav.org/incoming/ and contact the libav-devel mailing list.
[ac3 @ 0x1901e40] unsupported frame type : skipping frame
Speicherzugriffsfehler




[MartenR]

With the analog audio hopefully it will be fixed some time. Otherwise may be some external audio dacs may be developed for upgrading the pi.

Well as usual log files do not help i this case. If you can reproduce it with a recording, then I should be able to create a fix with the recording.
But otherwise I am lost. It seems, that either vomp is feeding libavcodec wrong or the stream was damaged and this lead to some undefined behaviour.

Marten