demux_lavf: fix stream switch returned index for no sound/video

If the argument given to demux_lavf audio/video switch code is not one
of -2, -1, or valid audio/video ID the code will treat it the same as
-2 (switch to no sound / no video). However the returned index was not
set to -2 in this case. Fix. Also change the returned index from -1 to
-2 when staying at no sound / video.

1 files changed, 8 insertions, 12 deletions

diff --git a/libmpdemux/demux_lavf.c b/libmpdemux/demux_lavf.c
index 6a32240ebd..e2fd964ae1 100644
--- a/libmpdemux/demux_lavf.c
+++ b/libmpdemux/demux_lavf.c
@@ -865,22 +865,18 @@ static int demux_lavf_control(demuxer_t *demuxer, int cmd, void *arg)
 	        }
 	    }
 
-            if(id == -2) { // no sound
-                i = -1;
-            } else if(id == -1) { // next track
+            if (id == -1) {   // next track
                 i = (curridx + 2) % (nstreams + 1) - 1;
                 if (i >= 0)
                     newid = pstreams[i];
-	    }
-	    else // select track by id
-	    {
-	        if (id >= 0 && id < nstreams) {
-	            i = id;
-	            newid = pstreams[i];
-	        }
-	    }
+	    } else if (id >= 0 && id < nstreams) {   // select track by id
+                i = id;
+                newid = pstreams[i];
+	    } else   // no sound
+                i = -1;
+
 	    if (i == curridx) {
-                *(int *) arg = curridx;
+                *(int *) arg = curridx < 0 ? -2 : curridx;
                 return DEMUXER_CTRL_OK;
             } else {
 	        ds_free_packs(ds);