replay: flush codec buffers after seeking (#34556)

* flush codec buffers after seeking

* replace avio_seek with the higher-level avformat_seek_file

* exit early

tools/replay/framereader.cc

@@ -177,7 +177,14 @@ bool VideoDecoder::decode(FrameReader *reader, int idx, VisionBuf *buf) {
         break;
       }
     }
-    avio_seek(reader->input_ctx->pb, reader->packets_info[from_idx].pos, SEEK_SET);
+
+    auto pos = reader->packets_info[from_idx].pos;
+    int ret = avformat_seek_file(reader->input_ctx, 0, pos, pos, pos, AVSEEK_FLAG_BYTE);
+    if (ret < 0) {
+      rError("Failed to seek to byte position %lld: %d", pos, AVERROR(ret));
+      return false;
+    }
+    avcodec_flush_buffers(decoder_ctx);
   }
   reader->prev_idx = idx;