[FFmpeg-cvslog] avcodec/ratecontrol: give some trivial tips in case of buffer underflows

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sun Sep  8 23:10:41 2013 +0200| [d8fb170da2e7edbfd250c1d8e1de6b1a0e965170] | committer: Michael Niedermayer

avcodec/ratecontrol: give some trivial tips in case of buffer underflows

See Ticket2725

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d8fb170da2e7edbfd250c1d8e1de6b1a0e965170
---

 libavcodec/ratecontrol.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/ratecontrol.c b/libavcodec/ratecontrol.c
index bf3321d..7db248e 100644
--- a/libavcodec/ratecontrol.c
+++ b/libavcodec/ratecontrol.c
@@ -328,6 +328,9 @@ int ff_vbv_update(MpegEncContext *s, int frame_size)
         rcc->buffer_index -= frame_size;
         if (rcc->buffer_index < 0) {
             av_log(s->avctx, AV_LOG_ERROR, "rc buffer underflow\n");
+            if (frame_size > max_rate && s->qscale == s->avctx->qmax) {
+                av_log(s->avctx, AV_LOG_ERROR, "max bitrate possibly too small or try trellis with large lmax or increase qmax\n");
+            }
             rcc->buffer_index = 0;
         }