avcodec/libmp3lame: do not attempt to flush lame if no data was input

this prevents the creation of a packet even though no single sample has ever
been input, which some confusion in the timestamp generation

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 2 insertions, 0 deletions

diff --git a/libavcodec/libmp3lame.c b/libavcodec/libmp3lame.c
index e6cb64b876..a8c39cc6c7 100644
--- a/libavcodec/libmp3lame.c
+++ b/libavcodec/libmp3lame.c
@@ -208,6 +208,8 @@ static int mp3lame_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
         default:
             return AVERROR_BUG;
         }
+    } else if (!s->afq.frame_alloc) {
+        lame_result = 0;
     } else {
         lame_result = lame_encode_flush(s->gfp, s->buffer + s->buffer_index,
                                         s->buffer_size - s->buffer_index);