avformat/movenc: Check input sample count

Fixes: division by 0
Fixes: fpe_movenc.c_199_1.wav
Fixes: fpe_movenc.c_199_2.wav
Fixes: fpe_movenc.c_199_3.wav
Fixes: fpe_movenc.c_199_4.wav
Fixes: fpe_movenc.c_199_5.wav
Fixes: fpe_movenc.c_199_6.wav
Fixes: fpe_movenc.c_199_7.wav
Found-by: #CHEN HONGXU# <HCHEN017@e.ntu.edu.sg>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/movenc.c

@@ -5269,6 +5269,11 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
     else
         samples_in_chunk = 1;
 
+    if (samples_in_chunk < 1) {
+        av_log(s, AV_LOG_ERROR, "fatal error, input packet contains no samples\n");
+        return AVERROR_PATCHWELCOME;
+    }
+
     /* copy extradata if it exists */
     if (trk->vos_len == 0 && par->extradata_size > 0 &&
         !TAG_IS_AVCI(trk->tag) &&