How to concat two frame_meta into one frame_meta , and add it to batch_meta?

Please provide complete information as applicable to your setup.

• Hardware Platform (Jetson / GPU) : Jetson Nano
• DeepStream Version: Deepstream 6.0
• JetPack Version (valid for Jetson only): Jetpack 4.6
• TensorRT Version: TensorRT 8.0
• NVIDIA GPU Driver Version (valid for GPU only)
• Issue Type( questions, new requirements, bugs): questions

In Preprocess plugin, assuming streammux’s batch_size = 1, how to copy the frame_meta and concat them(1920 x 1080 → 3840 x 2160), then add the concated frame_meta into batch_meta as nvinfer plugin’s inputs?

The pseudo code is as follows

batch_meta = gst_buffer_get_nvds_batch_meta (inbuf);

...

NvDsFrameMeta *frame_meta = NULL;
frame_meta = (NvDsFrameMeta *) (l_frame->data);

NvDsFrameMeta* copy_frame_meta = NULL;
copy_frame_meta = nvds_acquire_frame_meta_from_pool	(batch_meta);
// copy frame_meta twice
nvds_copy_frame_meta(frame_meta, copy_frame_meta);
nvds_copy_frame_meta(frame_meta, copy_frame_meta); 
// remove the original frame_meat
nvds_remove_frame_meta_from_batch(batch_meta, frame_meta);
// add concated frame_meat into batch_meata
nvds_add_frame_meta_to_batch(batch_meta, copy_frame_meta);

But the result is not what I want!the batch_size of batch_meta becomes larger and larger。

before batch meta's batchsize = 97
after batch meta's batchsize = 98
WARNING from element preprocess-plugin: Warning: exceeding preprocess batch-size (=network-input-shape[0]) => skipping sources

idx=7 network_input_shape[0]=7
Warning: Warning: exceeding preprocess batch-size (=network-input-shape[0]) => skipping sources

before batch meta's batchsize = 98
after batch meta's batchsize = 99
WARNING from element preprocess-plugin: Warning: exceeding preprocess batch-size (=network-input-shape[0]) => skipping sources

idx=7 network_input_shape[0]=7
Warning: Warning: exceeding preprocess batch-size (=network-input-shape[0]) => skipping sources

before batch meta's batchsize = 99
after batch meta's batchsize = 100

Hi @yangye ,
Sorry! Don’t understand the requirement.

Is “1920 x 1080 → 3840 x 2160” to scale the frame?
How can the concat work for above scale?