lfe-filter: Deal with empty input chunks

It is possible that we get a zero-length memchunk to work with.
Specifically, this happens the resampler (which is called before the
lfe-filter) consumes all the input data, but does not (yet) produce any
output data.

Reproduced using:

  pulseaudio --resample-method=soxr-mq
  pactl load-module module-null-sink sink_name=lfe_test channels=3 channel_map=front-left,front-right,lfe
  paplay --raw /dev/zero --rate=48000 -d lfe_test

Thanks to the original reporter for the backtrace:

Bug: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1496577

diff --git a/src/pulsecore/filter/lfe-filter.c b/src/pulsecore/filter/lfe-filter.c
index 8c79b55..5f5ace2 100644 (file)
--- a/src/pulsecore/filter/lfe-filter.c
+++ b/src/pulsecore/filter/lfe-filter.c
@@ -113,7 +113,7 @@ pa_memchunk * pa_lfe_filter_process(pa_lfe_filter_t *f, pa_memchunk *buf) {
     struct saved_state *s, *s2;
     void *data;
 
-    if (!f->active)
+    if (!f->active || !buf->length)
         return buf;
 
     /* Remove old states (FIXME: we could do better than searching the entire array here?) */