File Management for Improve Dense Trajectory 'idt_pipeline'

Hi everyone,

I am beginner in Matlab/Computer Vision and try to running code for 'idt_pipeline/idt_codebook' by Mt Jiang Yong Hui (Link).

I am using IXMAS dataset for Human Action Recognition and already manage to extract the feature by using ubuntu and save in gz file in the same path: (E:\MATLAB\IDT_FV\idt_pipeline-master\IDT_CodeBook\IXMAS). The 'IXMAS' directory contains directory for 'Cam0' for train that contain 11 classes and 'Cam1' for test that also contain 11 classes.

My 1st Questions:

In the beginning, I should start with file 'start_codebook.m'. But I stucked with Line 31-34.

params.dtf_dir='./data/idt_feature/pretrain/'; % idt feature file for pretrain 
params.train_list_dir=fullfile(path,'lists/split/train_test_list/'); % lists for pretrain
params.test_list_dir=fullfile(path,'lists/split/train_test_list');

a. What is the purpose for 'params.dtf_dir'? As root directory for train and test? (In my situation gz file) or an empty file that will stored the feature data later?

b. If assume it is the root directory, should I replace the code like this?

params.dtf_dir=fullfile(path, '.IXMAS/'); % idt feature file for pretrain 
params.train_list_dir=fullfile(path,'.IXMAS/cam00/'); % lists for pretrain
params.test_list_dir=fullfile(path,'.IXMAS/cam11/');

Unfortunatelly it gave an empty error:

Error using vl_kmeans
SIZE(DATA,1) is zero

Error in gmm_gen_codebook (line 35)
    [initMeans, assignments] = vl_kmeans(feats, params.cluster_count,'verbose', 'algorithm', 'elkan');

Error in pretrain (line 63)
 	gmm{i}=gmm_gen_codebook(feat,gmm_params);

Error in start_codebook (line 63)
            [ pca_coeff, gmm, all_train_files_codebook, all_train_labels_codebook, all_test_files_codebook,
            all_test_labels_codebook ] = pretrain(params);

My 2nd Questions:

By referring 'subsample.m' function (link), Line 14 and Line 17. From my understanding it is file pattern for the extension for the file. In my case the format is '*.gz'.

switch t_type
    case 'train'
        tt_list_dir=params.train_list_dir;
        reg_pattern='trainlist*'; % name pattern of trainlist
    case 'test'
        tt_list_dir=params.test_list_dir;
        reg_pattern='testlist*'; % name pattern of testlist
    otherwise
        error('Unknown file pattern!');
end

Should I replace the code like this?:

switch t_type 
    case 'train'
        tt_list_dir=params.train_list_dir;
        reg_pattern='*.gz'; % name pattern of trainlist 
    case 'test'
        tt_list_dir=params.test_list_dir;
        reg_pattern='*.gz'; % name pattern of testlist
    otherwise
        error('Unknown file pattern!');
end

Thanks in advance for those can help and guide me.