How to force min_length in pipeline text_generation

Hi there

My goal is to use GPT-2 for Midi Data - like museNet.
The data input are numbers like as follows:

   23 24 177
   12 
   23 12 15

i trained the model from scratch described in this post: https://discuss.huggingface.co/t/gpt2-training-from-scratch-in-german/1157

While using pipeline(“text-generation”), the output length is very short. Is this due to the data input? how can i force a min_length with pipeline?