[pulseaudio-discuss] Audio APP (sink-input) bind to the sink with only unplugged hdmi-audio ports on it

[Hui Wang]

On 2018年09月30日 18:30, Tanu Kaskinen wrote:
> On Sun, 2018-09-30 at 15:03 +0800, Hui Wang wrote:
>> This issue is also reported to:
>> https://gitlab.freedesktop.org/pulseaudio/pulseaudio/issues/579
>>
>> Recently we found a weird issue on many laptops with the ubuntu 18.04,
>> it uses the pulseaudio-11.1 (I guess the PA of the latest version also
>> has this problem). The issue is like this:
>>
>>   1. boot the system up without plugging a hdmi monitor
>>   2. run an audio app to play sound (e.g. $speaker-test)
>>   3. the sound outputs from analog-speaker
>>   4. plug a monitor with audio capability (through DP or HDMI port)
>>   5. the sound still outputs from analog-speaker
>>   6. open sound-setting (gnome-control-center --> choose sound), you will
>>      see two output devies: speaker and HDMI audio
>>   7. choose HDMI audio, the sound will switch to HDIM audio from speaker
>>      (pa will remember speaker-test prefer to use hdmi-audio sink)
>>   8. unplug the monitor, the default-sink is switching to analog-speaker,
>>      but the sound of speaker-test still route to hdmi-audio sink
>>   9. run other sound apps, they all route sound to default sink
>>      (analog-speaker), but speaker-test always routes to hdmi-audio sink,
>>      as a result, speaker-test can't output sound anymore unless we
>>      replug a monitor with audio capability then the speaker-test output
>>      from hdmi-audio again.
>> 10. if we want the speaker-test to route to analog-speaker, two ways:
>>      run pacmd move-sink-input or plug a monitor, after two audio devices
>>      (hdmi audio and speaker) show up in the sound-setting, select
>>      analog-speaker manually.
>>
>> This issue only happens on the laptops with 2 audio cards, analog
>> devices on one card, hdmi audio on the other card. This kind of laptops
>> are very common, like I+A (Intel graphic + Amd Graphic), I+N(Intel +
>> Nvidia), and A AMD.
>>
>> This issue will not happen on the laptops with only Intel graphic card,
>> since both analog and hdmi audio belong to one sound card. When hdmi
>> monitor is unplugged, the hdmi sink will be removed from PA, then all
>> sink-inputs will route to the only left sink: analog-sink.
>>
>> This issue will not happen on BT or USB audio. Unlike hdmi audio, BT and
>> USB audio cards will be removed totally from PA when they are
>> unpluged/unconnected, so they don't have this issue as well.
>>
>> The root cause of this issue is although the hdmi monitor is unplugged,
>> the hdmi-sink still exists, and sink-input is selected by user to bind
>> to this sink, so the pa doesn't care about if this sink has valid port
>> or not, it bind the sink-input to this sink unconditionally.
>>
>> Maybe we could improve it like this: if the user selected sink only has
>> available_no ports, the pa will switch all sink-inputs of this sink to
>> other sinks (like default_sink) temporarily, once the selected sink has
>> availble ports, all sink-inputs switch back to this sink.
>>
>> Any good ideas?
> The plan has been to do the following (but I haven't found the time to
> implement it):
>
> Streams currently have a "save_sink" flag that tells whether the
> current sink should be remembered and restored by module-stream-
> restore. That flag should be replaced with a "preferred_sink" string
> that is set when the user moves the stream. module-stream-restore
> should remember and restore that string.
>
> When the user moves a stream to the current default sink, the
> "preferred_sink" string should be set to NULL and module-stream-restore
> should clear the routing for that stream in the stream database. From
> that point on the stream will be always routed to the default sink.
>
> When a stream is created, module-stream-restore should set the
> "preferred_sink" string and if that sink exists, the core should set
> that sink as the initial routing for the new stream.
>
> When the default sink changes, the streams from the old default sink
> should be moved to the new default sink, unless the "preferred_sink"
> string is set to the old default sink and the active port of the old
> default sink is not unavailable. This should be done by the core.
>
> When the active port of a sink becomes unavailable, all streams from
> that sink should be moved to the default sink. This should be done by
> the core.
>
> When a new sink appears or the active port of an existing sink changes
> state from unavailable, all streams that have their "preferred_sink"
> set to the new sink should be moved to the new sink. This should be
> done by the core.
>
> As a result, module-stream-restore doesn't need to move streams any
> more, it only needs to manage the "preferred_sink" variables. Some
> other modules can perhaps be simplified as well.
>
> The same logic should of course be implemented for capture streams as
> well.
>
> Would you be willing to implement this?
>
Got it, I will take some time to understand your plan first, then have a 
try to implement it.

Thanks,

Hui.