# Enhancing Sign Language Recognition Performance Through Coverage-Based Dynamic Clip Generation
## 3 Methods
### Clip Generation  
The process of generating clips in the proposed method is described as follows. Table 4 presents the symbols and their corresponding descriptions used in the explanation of the clip generation process. Given the total number of frames in a video and the desired number of frames per clip, clips are extracted using a sliding window approach. This approach divides the video into smaller fixed length segments, ensuring that each clip covers a specific portion of the video. The clip generation algorithm is presented in Algorithm 1. As shown in Algorithm 1, the procedure follows three different cases depending on the relationship between the total number of frames in the video (\(F_{total}\)) and the desired number of frames per clip (\(F_{clip}\)):  
* \(F_{total}>F_{clip}\): The total number of frames exceeds the number of frames needed for a single clip. \begin{table}
\begin{tabular}{c l} \hline \hline
**Symbols** & **Descriptions** \\ \hline \(F_{total}\) & Total number of frames in the video \\ \hline \(F_{clip}\) & Number of frames included in each clip \\ \hline \(N_{clip}\) & Total number of clips \\ \hline \(i\) & Index of the current clip \\ \hline \(s_{i}\) & The starting frame index for the \(i\)-th clip \\ \hline \(L_{i}\) & The list of selected frame indices for the \(i\)-th clip \\ \hline \(\mathbb{S}_{clip}\) & A set containing all \(L_{i}\), i.e., \(\mathbb{S}_{clip}=[L_{0},L_{1},\ldots,L_{N_{clip}-1}]\) \\ \hline \(Cov\) & Ratio of frames covered by clips to total frames in the video \\ \hline \(F_{sum}\) & Total selected frames across all clips (including duplicates) \\ \hline \(T_{Cov}\) & Target coverage \\ \hline \(N_{opt}\) & The optimal number of clips calculated for the video \\ \hline \end{tabular}
\end{table} 
Table 4: List of symbols and their descriptions. This if condition checks whether \(F_{total}\) is greater than \(F_{clip}\). This part of the algorithm runs when the video contains more frames than are required for one clip, meaning the video can be split into multiple clips. * The for loop iterates over \(i\) from 0 to \(N_{clip}-1\), as shown in Algorithm 1, Line 4, meaning the algorithm runs once for each of the \(N_{clip}\) clips to be generated. For each iteration, the starting index and the corresponding frames for the current clip are calculated. * \(N_{clip}\) clips are selected by evenly spacing them throughout the video. * The starting index for each clip is computed as shown in Equation (1): \[s_{i}=\frac{F_{total}-F_{clip}}{N_{clip}-1}\times i\] (1) * Each clip consists of \(F_{clip}\) consecutive frames starting from \(s_{i}\). The set \(L_{i}\), which represents the frame indices for the \(i\)-th clip, is defined as shown in Equation (2): \[L_{i}\leftarrow\{s_{i}+j\mid j=1,2,\ldots,F_{clip}\}\] (2) where each frame index \(s_{i}+j\) corresponds to a frame in the \(i\)-th clip, starting from \(s_{i}\) and continuing for \(F_{clip}\) frames. In this case, where the total number of frames \(F_{total}\) is greater than the number of frames required for a single clip \(F_{clip}\), the video is divided into \(N_{clip}\) clips, evenly distributed across the video. The starting index for each clip is computed using the formula for \(s_{i}\) in Equation (1), and each clip contains \(F_{clip}\) consecutive frames starting from \(s_{i}\). * \(F_{total}=F_{clip}\): The total number of frames in the video is equal to the number of frames in a single clip. * Since each clip contains all the frames of the video, every clip has the same frame indices. Thus, the set of frame indices for the \(i\)-th clip, \(L_{i}\), is defined as shown in Equation (3). \[L_{i}\leftarrow\{1,\ldots,F_{clip}\}\] (3) where each frame index corresponds to the full range of frames in the video, from the first to the last. * The set \(L_{i}\) for each clip is then added to the overall set \(\mathbb{S}_{clip}\), as shown in Equation (4). \[\mathbb{S}_{clip}\leftarrow\mathbb{S}_{clip}\cup\{L_{i}\}\] (4) This ensures that all frame indices are included in the final set of clips.