avidemux: improve audio vbr detection

Subsequent entry time calculations use blockalign value to determine
number of frames per chunk, and blockalign == 1 is then most unlikely to result
in reasonable values (which also aligns with "spec").

gst/avi/gstavidemux.c

@@ -1988,11 +1988,12 @@ gst_avi_demux_parse_stream (GstAviDemux * avi, GstBuffer * buf)
             GST_DEBUG_OBJECT (element, "marking video as VBR, res %d", res);
             break;
           case GST_RIFF_FCC_auds:
-            stream->is_vbr = (stream->strh->samplesize == 0)
-                && stream->strh->scale > 1;
             res =
                 gst_riff_parse_strf_auds (element, sub, &stream->strf.auds,
                 &stream->extradata);
+            stream->is_vbr = (stream->strh->samplesize == 0)
+                && stream->strh->scale > 1
+                && stream->strf.auds->blockalign != 1;
             sub = NULL;
             GST_DEBUG_OBJECT (element, "marking audio as VBR:%d, res %d",
                 stream->is_vbr, res);