If we have a disconnected output, read data only passively (and don't
cause input to be written). Otherwise, we're in danger of making
libavfilter queue too many frames on other outputs which are connected
to the same input, but don't read as quickly.
Also don't set pad->output_needed in this specific case, because it
would nonsensically make lavfi_process() return true, even if nothing is
going on.
This commit breaks if there is a simple filter chain with a connected
input, but a disconnected output, like
--lavfi-complex='[aid1] copy [ao]'
and the audio output didn't initialize correctly. This will eventually
starve video as the audio packet queue get full (it will print a
warning, and then assume video EOF and exit).
But whatever.
Probably fixes#4118.
As a positive side-effect, this also errors out gracefully for the
extremely unlikely but possible case certain builtin filters are not
available. (This could happen only with crippled libavfilter builds that
can't be used by anything using its public API.)
Especially useful to see what video formats are involved on the various
filter links.
I suspect this function is not available on Libav, so add necessary
ifdeffery preemptively.
This was dumb. Could make it burn 100% CPU and not exit at the end.
(Because it would retry as instructed, instead of terminating playback.)
It also needs to consider EOF as waiting for input. lavfi_process() will
decide if it's really EOF, or if further input might come in the future.
Without this, it'd would think that it does not need to wait for input,
i.e. that new input will be available immediately.
(Not so fond of the duplication of subtle logic.)
It doesn't provide this function. The code is not really designed to
work without it, so it will probably mess up big time, but at least
make it compile again.
See --lavfi-complex option.
This is still quite rough. There's no support for dynamic configuration
of any kind. There are probably corner cases where playback might freeze
or burn 100% CPU (due to dataflow problems when interaction with
libavfilter).
Future possible plans might include:
- freely switch tracks by providing some sort of default track graph
label
- automatically enabling audio visualization
- automatically mix audio or stack video when multiple tracks are
selected at once (similar to how multiple sub tracks can be selected)
wm4