log error on filter graph

Author: maxnut

src/recorder.cpp

@@ -257,8 +257,11 @@ bool Recorder::writeFrame(const std::vector<uint8_t>& frameData) {
 }
 
 void Recorder::filterFrame(AVFrame* inputFrame, AVFrame* outputFrame) {
-    if (av_buffersrc_add_frame(m_buffersrcCtx, inputFrame) < 0) {
+    int ret = av_buffersrc_add_frame(m_buffersrcCtx, inputFrame);
+    if (ret < 0) {
         std::cerr << "Error feeding frame to filter graph.\n";
+        char errbuf[AV_ERROR_MAX_STRING_SIZE];
+        av_strerror(ret, errbuf, AV_ERROR_MAX_STRING_SIZE);
         avfilter_graph_free(&m_filterGraph);
         return;
     }