ffmpeg script outputs video with unexpected resolution and frame rate despite scaling and fps filtering

This 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.

#!/usr/bin/env bash

# Constants
MAX_RESOLUTION=540
MAX_FPS=15
MAX_BITRATE="500k"
CRF_VALUE=30
MAX_AUDIO_BITRATE="64k"

# 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

posted 3 months ago

CC BY-SA 4.0

3mo ago

ShadowsRanger‭

103 reputation 9 1 -9 46

Your issue lies in the application of scaling and fps filtering. Both SCALING and FPS_FILTER are being set conditionally, and if both are needed, one will override the other since both are using -vf. Combine them in one -vf argument to avoid conflict:

if [ $WIDTH -lt $HEIGHT ]; then
    SHORTER_SIDE=$WIDTH
    if [ $WIDTH -gt $MAX_RESOLUTION ]; then
        SCALING="scale=$MAX_RESOLUTION:-2"
    fi
else
    SHORTER_SIDE=$HEIGHT
    if [ $HEIGHT -gt $MAX_RESOLUTION ]; then
        SCALING="scale=-2:$MAX_RESOLUTION"
    fi
fi

if [ $FPS -gt $MAX_FPS ]; then
    if [ -z "$SCALING" ]; then
        SCALING="fps=$MAX_FPS"
    else
        SCALING="$SCALING, fps=$MAX_FPS"
    fi
fi

Then apply the combined filter:

ffmpeg_cmd=(
    "-i" "$FILE"
    "-vf" "$SCALING"
    "-c:v" "libx265"
    "-preset" "slow"
    "-crf" "$CRF_VALUE"
    "-c:a" "aac"
    "-b:a" "$AUDIO_BITRATE"
    "-movflags" "+faststart"
    "$OUTPUT_FILE"
)

This ensures both scaling and frame rate adjustments are applied correctly.

posted 2 months ago

CC BY-SA 4.0

harmony‭

37 reputation 0 3 2 0