QtCS2021 - Qt Multimedia

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Session Summary

Let's talk about where we are with porting Qt Multimedia to Qt 6, what changes we have made compared to Qt 5, what needs to be done for Qt 6.2, and what the next steps are.

Session Owners

  • Lars Knoll (lars.knoll@qt.io)
  • Veli-Pekka Heinonen (veli-pekka.heinonen@qt.io)


Slides

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Notes

Q: Is it also possible to capture the screen content?

A: Yes, after 6.2

Q: Porting guide coming? (Samuel Gaist)

A: there’s something now but a bit more would be needed.

Q: how about professional sound arts with more than 8 channels?

A: in principle a media file with many channels work, but the issue is with assignment, need to know where to put those. Also would like to support those for capturing.

Q: I think there was mention of multiple stream and subtitle support, any chance of showing the api for that? (Arjen Hiemstra)

A: shown

Q: Would it be possible to stream a capture output? Combined with the future screen capture, we could get a "simple" remote display for Qt (Vladimir Minenko)

A: That is the goal, for instance using RTP, but need to look at it additionally.

Q: Samuel Gaist: are the widgets on par regarding rendering exotic formats

A: yes they are on par, we’ve extended the format support

Q: I do have a question about audio routing how to do it

A: specify AudioOutput as a channel and then use the default, have to explicitly add the QAudioOutput channel

Q: (Vladimir Minenko) IIRC, HiFi and High End audio playback requires sync information to reduce the jitter. I know this as a "user". High End devices use the sync down to the USB data stream (my mic is still not working)

A: usually backend pipelines handle this. You can timestamp your audio channels also.

QIs RTSP supported?

A: on the receiving end yes. For capturing not supported, needs more testing.

Q: I’m gonna write a cd audio player with this, but that's not really relevant now

A: this may require some backend development

Q: I'm still thinking of High End playback.... IMHO, you might need too control the buffer sized on the Qt side to make them aligned with the source sync... Otherwise Qt would cause a jitter. IMHO... Certainly in case if we want to support high end audio

A: let’s discuss this

Note: there is a pending change request contribution for webassembly audio for 6.3 using openAL

Link to the Qt 6 Multimedia Survey: https://forms.office.com/Pages/ResponsePage.aspx?id=Z7HQIE15ikSdAarszBEkrPrlToWem8lPgmANnRBsE_tURTdWSkw1U05PRzBCT00yWlZYNTBEODhRSi4u