GStreamer hangs with v4l2src, compositor, tee and fakesync

[Terry Barnaby]

On 09/11/2021 14:49, Nicolas Dufresne wrote:
> Le mardi 09 novembre 2021 à 14:11 +0000, Terry Barnaby a écrit :
>> Hi,
>>
>> I forgot to mention, I have recently found that adding "! identity
>> drop-allocation=true" before the tee appears to fix/"work around" the
>> issue but I have no idea why.
> Strange, having fakesink in the set of pads inside the tee should have the same
> effect, since fakesink does not reply to the allocation query. v4l2src will then
> guess the number of required buffer and enable a copy threshold if it's running
> our of buffer (v4l2 works best with fixed number of pre-allocated buffers).
>
> Also strange that it works for me, though I probably have a different GL stack
> (which act as dmabuf importer) and different set of cameras. Have you tested
> with fakevideosink as a curiosity ? This one replies to the allocation query,
> allowing tee to aggregate and reply to upstream.
>
Just tried with fakevideosink and it made no difference.