## 4 Opportunities and Open Research Areas in VANET Multimedia  
In recent years, there has been a growing recognition of the importance of multimedia transmission in VANETs. The ability to transmit multimedia data, which include images, videos, or audio-visual content, could bring several significant benefits to enhance communication, safety, and efficiency in vehicular networks. Figure 4 provides an overview of the opportunities for multimedia in VANETs. One of the key aspects highlighting the importance of multimedia transmission is to provide drivers with real-time information about traffic conditions, road closures, and other hazards. Current Traveler Information Messages (TIMs) provide situation awareness to drivers; however, they are only text-based. Researchers have been searching for ways to optimize notifications to drivers without congesting the DSRC VANET. This is particularly crucial in light of bandwidth restrictions inherent in VANETs, which can become more pronounced as vehicles move farther away from roadside units (RSUs). The communication speeds may experience fluctuations as vehicles traverse varying distances from RSUs, necessitating efficient protocols and technologies to ensure the reliable and timely dissemination of critical information. DSRC V2X is a wide topic, and the opportunities discussed in this section are only geared toward the transmission of data from the roadside unit to the vehicle, also known as Infrastructure to Vehicle (V2I), as shown in Figure 5.  
In contemporary studies, video transmission within DSRC VANET poses the challenge of consuming excessive bandwidth and congestion, while pre-programmed images that are populated within the dashboard in the case of TIMs only show a repeated image with only a beep. The research area in real-time dissemination of short audio-visual information has been largely ignored. Transmitting and presenting real-time audio-visual information about actual incidents could help drivers be aware of the real situation and mitigate risk, thereby helping to reduce road accidents. For example, a short audio-visual clip could be used to warn drivers of upcoming curved road hazards or to provide a view of the road ahead with audio warnings. Emergency notifications and public safety are other critical areas where audio-visual transmission plays an essential role. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt}} \hline \hline
**Metric Category** & **Description** \\ \hline Bandwidth Efficiency & Evaluating the efficiency of multimedia compression and transmission techniques with limited bandwidth [50; 51]. \\ \hline QoS and QoE Assessment & Measuring Quality of Service (QoE) and Quality of Experience (QoE) metrics, including latency and video quality [51]. \\ \hline Error Resilience Metrics & Assessing the effectiveness of error resilience mechanisms in maintaining multimedia data integrity. \\ \hline Security and Privacy & Evaluating security and privacy measures to ensure the confidentiality and integrity of multimedia content [52]. \\ \hline Fading Impact Analysis & Studying the impact of signal fading on multimedia transmission and proposing solutions for mitigation [53]. \\ \hline Technical Resource Optimization & Developing protocols and strategies to optimize multimedia transmission in the face of resource constraints. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Metrics of Study in VANET Multimedia Transmission. The use of audio-visual transmission in DSRC, specifically in the Infrastructure-to-Vehicle (I2V) context, presents various opportunities and advantages. Firstly, it offers a richness of information by combining visual and auditory modalities, providing a comprehensive representation of the environment. By integrating textual information with images, audio-visual transmission enables drivers to quickly understand critical details and make informed decisions, enhancing situational awareness and overall road safety. Moreover, audio-visual transmission contributes to the bandwidth economy in DSRC.