The node.link-group property marks streams that are internally linked
together in some way. It is used to relate the input and output streams
of some of the module streams.
This also brings the advantage that all tools, examples, modules, components
can also be compiled standalone out-of-tree using libpipewire from the system
This is not too useful while looking at pipeline graphs, etc. We will
likely want to expand this to also include the module id or something to
distinguish multiple echo-cancel instances (which we can currently do
via the factory ID).
Mostly uses the existing infrastructure, but the webrtc canceller has a
fixed blocksize, so we:
1. Use the canceller blocksize if configured
2. Accumulate output data in a ringbuffer
3. Push out the data in the required chunk size
This aggregates buffers from the capture stream and the sink in the
corresponding process callbacks, and runs processing based on the
desired resampler rate if there is one.
We allow the ringbuffer in which we capture buffers to grow to some
extent, as that seems to be required for playback to occur smoothly.
Whether this is hiding some other underlying problem likely needs
investigation.
Just like the real free() we should just ignore a NULL pointer, makes the
caller code easier for those instances where properties are optional.
Patch generated with concinelle with a few manual fixes.
SPA_MEMBER is misleading, all we're doing here is pointer+offset and a
type-casting the result. Rename to SPA_PTROFF which is more expressive (and
has the same number of characters so we don't need to re-indent).
Only implement the null echo cancel implementation for now.
And skeleton webrtc echo cancel implementation
It uses 4 streams arranged as:
input ---+---> source
^
|
sink ---+---> output
The output of the source is the filtered input of the input stream
(linked a master source) based on the data going from sink to
the output (linked to a master sink).
All streams are arranged in the same group so that the echo canceler
does not have to deal with clock drift. For echo cancelers that can
handle clock drift we might want place the source and sink chains
in different groups.
