On Thu, Nov 8, 2018, at 20:49, pulseaudio-discuss-request@xxxxxxxxxxxxxxxxxxxxx wrote: > Message: 4 > Date: Thu, 8 Nov 2018 21:31:52 +0500 > From: "Alexander E. Patrakov" <patrakov@xxxxxxxxx> > To: General PulseAudio Discussion > <pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx> > Subject: Re: PulseAudio null sink monitor gives > distorted audio randomly > Message-ID: <e96e0c84-6a83-78f5-dab3-60a39b6eb9a2@xxxxxxxxx> > Content-Type: text/plain; charset=utf-8; format=flowed > > [resending to the list, really this time] > > On 11/8/18 7:44 PM, Tanu Kaskinen wrote: > > > The problem is most likely due to this bug regarding monitor sources: > > https://gitlab.freedesktop.org/pulseaudio/pulseaudio/issues/304 > > > > Whenever the monitored sink has a rewind, a chunk of audio is > > apparently duplicated in the monitor source. It would be great if > > someone could figure out what goes wrong in the monitor rewinding code. > > Let me quote the main mistake, from src/pulse/stream.h: > > > * The latency is stored in \a *r_usec. In case the stream is a > > * monitoring stream the result can be negative, i.e. the captured > > * samples are not yet played. In this case \a *negative is set to 1. > > I.e., the design mistake is that monitor sources allow one to capture > samples that have not yet been played. This is always wrong, as those > samples can be overwritten by a rewind, and there is no "uncapture" to > compensate. So the fix would be to make sure that monitor sources > capture not what was just written to them, but what was actually played > and can no longer be overwritten. I.e., change the latency from negative > to small positive. > > -- > Alexander e. Patrakov Thanks for digging into this! Some questions: 1. Is there any workaround for this without a proper bugfix and a new release? 2. Is this a question of buffer underrun / jitter bcause of CPU usage? What is the cause for "monitor rewinds", why is it needed? 3. Why are the artifacts gone sometimes and sometimes the appear after PulseAudio restart? -Mikael _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
