video-merger

Video Merge Tool

Merge multiple short video clips into one complete video, with support for transition effects and unified processing.

Features

1. Sequential merging: Concatenate multiple videos in order
2. Transition effects: Add transitions such as fade in/fade out
3. Unified format: Ensure the output format is consistent
4. Background music: Add unified background music

Usage

合并这些视频: clip1.mp4, clip2.mp4, clip3.mp4

把 ./output/shorts/ 目录下的所有短视频合并成一个

Instructions

Step 1: Prepare the file list

# 创建视频列表文件
mkdir -p ./temp

# 方式1: 指定文件
cat > ./temp/merge_list.txt << 'EOF'
file './output/shorts/clip1.mp4'
file './output/shorts/clip2.mp4'
file './output/shorts/clip3.mp4'
EOF

# 方式2: 自动扫描目录
for f in ./output/shorts/*.mp4; do
  echo "file '$f'"
done > ./temp/merge_list.txt

cat ./temp/merge_list.txt

Step 2: Unify the video format

# 确保所有视频格式一致（分辨率、帧率、编码）
mkdir -p ./temp/normalized

while read -r line; do
  file=$(echo "$line" | sed "s/file '//;s/'//")
  if [ -f "$file" ]; then
    basename=$(basename "$file")
    
    ffmpeg -i "$file" \
      -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:-1:-1:color=black" \
      -r 30 \
      -c:v libx264 -preset fast -crf 23 \
      -c:a aac -b:a 128k -ar 44100 \
      "./temp/normalized/$basename"
  fi
done < ./temp/merge_list.txt

# 更新列表
for f in ./temp/normalized/*.mp4; do
  echo "file '$f'"
done > ./temp/normalized_list.txt

Step 3: Simple merge (no transitions)

# 使用 concat demuxer 直接合并
ffmpeg -f concat -safe 0 -i ./temp/normalized_list.txt \
  -c copy \
  ./output/merged/merged_simple.mp4

echo "✅ 简单合并完成"

Step 4: Merge with transition effects

# 淡入淡出转场
# 获取视频数量和时长信息
VIDEO_COUNT=$(wc -l < ./temp/normalized_list.txt)
TRANSITION_DURATION=0.5

# 使用 xfade 滤镜添加转场
# 注意: 需要 FFmpeg 4.3+

# 对于2个视频的简单示例:
VIDEO1="./temp/normalized/clip1.mp4"
VIDEO2="./temp/normalized/clip2.mp4"
VIDEO1_DURATION=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 "$VIDEO1")

OFFSET=$(echo "$VIDEO1_DURATION - $TRANSITION_DURATION" | bc)

ffmpeg -i "$VIDEO1" -i "$VIDEO2" \
  -filter_complex "
    [0:v][1:v]xfade=transition=fade:duration=${TRANSITION_DURATION}:offset=${OFFSET}[v];
    [0:a][1:a]acrossfade=d=${TRANSITION_DURATION}[a]
  " \
  -map "[v]" -map "[a]" \
  -c:v libx264 -preset fast -crf 23 \
  -c:a aac -b:a 128k \
  ./output/merged/merged_fade.mp4

echo "✅ 淡入淡出转场合并完成"

Step 5: Add background music

MERGED_VIDEO="./output/merged/merged_simple.mp4"
BGM_FILE="./assets/bgm.mp3"
OUTPUT="./output/merged/merged_with_bgm.mp4"

if [ -f "$BGM_FILE" ]; then
  # 获取视频时长
  VIDEO_DURATION=$(ffprobe -v error -show_entries format=duration \
    -of default=noprint_wrappers=1:nokey=1 "$MERGED_VIDEO")
  
  # 混合音频 (原声 + BGM)
  ffmpeg -i "$MERGED_VIDEO" -i "$BGM_FILE" \
    -filter_complex "
      [1:a]volume=0.15,aloop=loop=-1:size=2e+09[bgm];
      [bgm]atrim=0:$VIDEO_DURATION[bgm_trimmed];
      [0:a][bgm_trimmed]amix=inputs=2:duration=first:dropout_transition=2[a]
    " \
    -map 0:v -map "[a]" \
    -c:v copy \
    -c:a aac -b:a 128k \
    "$OUTPUT"
  
  echo "✅ 背景音乐已添加"
else
  echo "⚠️ 未找到背景音乐文件: $BGM_FILE"
  cp "$MERGED_VIDEO" "$OUTPUT"
fi

Step 6: Add opening and ending

INTRO="./assets/intro.mp4"
OUTRO="./assets/outro.mp4"
MAIN="./output/merged/merged_simple.mp4"
FINAL="./output/merged/final.mp4"

# 创建包含片头、主体、片尾的列表
cat > ./temp/final_list.txt << EOF
file '$INTRO'
file '$MAIN'
file '$OUTRO'
EOF

# 先标准化格式
for f in "$INTRO" "$MAIN" "$OUTRO"; do
  if [ -f "$f" ]; then
    basename=$(basename "$f")
    ffmpeg -i "$f" \
      -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:-1:-1" \
      -r 30 -c:v libx264 -preset fast -crf 23 \
      -c:a aac -b:a 128k -ar 44100 \
      "./temp/final_$basename"
  fi
done

# 合并
ffmpeg -f concat -safe 0 -i ./temp/final_list.txt \
  -c copy \
  "$FINAL"

Available transition effects

Transition types using the xfade filter:

Effect	Description
fade	Fade in/out
wipeleft	Wipe left
wiperight	Wipe right
wipeup	Wipe up
wipedown	Wipe down
slideleft	Slide left
slideright	Slide right
slideup	Slide up
slidedown	Slide down
circlecrop	Circle crop
rectcrop	Square crop
distance	Distance transform
fadeblack	Fade through black
fadewhite	Fade through white
radial	Radial transition
smoothleft	Smooth left shift
smoothright	Smooth right shift

Output

• Simple merge: ./output/merged/merged_simple.mp4
• With transitions: ./output/merged/merged_fade.mp4
• With background music: ./output/merged/merged_with_bgm.mp4
• Final version: ./output/merged/final.mp4

Directory structure

./output/
├── shorts/      # 原始短视频片段
├── merged/      # 合并后的视频
└── thumbnails/  # 封面图

./assets/
├── intro.mp4    # 片头
├── outro.mp4    # 片尾
└── bgm.mp3      # 背景音乐