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The second script applies filters dynamically based on the video's dimensions and frame rate. The audio handling is more sophisticated, checking and adjusting the bitrate separately. It's more flexible in codec selection, only converting when truly necessary. It uses glob patterns for file matching, potentially offering better efficiency.

```bash
#!/usr/bin/env bash

# Constants
MAX_RESOLUTION=540
MAX_FPS=24
MAX_BITRATE="500k"
CRF_VALUE=30
MAX_AUDIO_BITRATE="128k"

# Check if the directory argument is provided
if [ $# -eq 0 ]; then
    echo "Usage: $0 <directory>"
    exit 1
fi

TARGET_DIR="$1"

# Function to log messages
log() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1"
}

# Function to handle errors
handle_error() {
    log "Error occurred: $1"
    exit 1
}

# Main conversion loop
for FILE in "$TARGET_DIR"/*.{mp4,mkv,avi,mov,m4v,wmv}; do
    [ -e "$FILE" ] || continue
    log "Processing: $FILE"
    
    # Get video dimensions and frame rate
    DIMENSIONS=$(ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=s=x:p=0 "$FILE")
    WIDTH=$(echo $DIMENSIONS | cut -d'x' -f1)
    HEIGHT=$(echo $DIMENSIONS | cut -d'x' -f2)
    FPS=$(ffprobe -v error -select_streams v:0 -count_packets -show_entries stream=r_frame_rate -of csv=p=0 "$FILE" | bc -l | awk '{printf("%d\n",$1 + 0.5)}')
    
    FILTERS=()

    if [ $WIDTH -lt $HEIGHT ]; then
        SHORTER_SIDE=$WIDTH
        if [ $WIDTH -gt $MAX_RESOLUTION ]; then
            FILTERS+=("scale=$MAX_RESOLUTION:-2")
        fi
    else
        SHORTER_SIDE=$HEIGHT
        if [ $HEIGHT -gt $MAX_RESOLUTION ]; then
            FILTERS+=("scale=-2:$MAX_RESOLUTION")
        fi
    fi
    
    if [ $FPS -gt $MAX_FPS ]; then
        FILTERS+=("fps=$MAX_FPS")
    fi

    # Combine filters if any exist
    if [ ${#FILTERS[@]} -gt 0 ]; then
        FILTER_OPTION="-vf $(IFS=,; echo "${FILTERS[*]}")"
    else
        FILTER_OPTION=""
    fi
    
    audio_bitrate=$(ffprobe -v error -select_streams a:0 -show_entries stream=bit_rate -of default=noprint_wrappers=1:nokey=1 "$FILE")
    audio_filter=""
    if [ "$audio_bitrate" -gt "$MAX_AUDIO_BITRATE" ]; then
        audio_filter="-b:a $MAX_AUDIO_BITRATE"
    fi

    # Get codec info
    CODEC_INFO=$(ffprobe -v error -select_streams v:0 -show_entries stream=codec_name -of default=noprint_wrappers=1:nokey=1 "$FILE")
    
    # Check if conversion is needed
    if [[ "$CODEC_INFO" != "hevc" && "$CODEC_INFO" != "h265" ]] || [ "$FPS" -gt "$MAX_FPS" ] || [ $SHORTER_SIDE -gt $MAX_RESOLUTION ] || [ "$audio_bitrate" -gt "$MAX_AUDIO_BITRATE" ]; then
        OUTPUT_FILE="${FILE%.*}.h265.mkv"
        
        # Combine scaling, FPS filtering, and codec selection
        ffmpeg_cmd=(
            "-i" "$FILE"
            $FILTER_OPTION
            "-c:v" "libx265"
            "-preset" "slow"
            "-crf" "$CRF_VALUE"
            "-c:a" "aac"
            $audio_filter
            "-movflags" "+faststart"
            "$OUTPUT_FILE"
        )
        
        log "Executing FFmpeg command: ${ffmpeg_cmd[*]}"
        ffmpeg "${ffmpeg_cmd[@]}" || handle_error "FFmpeg failed to encode $FILE"
        
        log "Conversion completed successfully."
    else
        log "No conversion needed for $FILE"
    fi
done
```