Comment # 6 on bug 1210750 from Roland Kummler

console messages during video playback:

digiKam-8.1.0-x86-64.appimage, sound available

...
QtAV::AVDemuxer::setStreamIndex: invalid index 0 ( valid is 0 ~ 0 ) for stream
type 2
QtAV::audioFormatToAL: OpenAL audioFormatToAL error (null context): 0xa004
QtAV::AudioResamplerFF::prepare: src audio parameters 'channel layout(or
channels),sample rate and sample format must be set before initialize resampler
QtAV::VideoDecoderFFmpegBase::decode: no frame could be decompressed: Error
number 54487 occurred 0 / 54487
QtAV::VideoThread::run: invalid video frame from decoder. undecoded data size:
0

digikam 8.1.0 KDE:Extra repo, no sound

...
digikam.qtav.warn: invalid index 0 ( valid is 0 ~ 0 ) for stream type 2
digikam.qtav.warn: invalid video frame from decoder. undecoded data size: 0