title: How to concatenate two or more videos with same width and different height in FFMpeg and to maintain the same aspect ratio?
body: <p>I have five video parts to concat all. Each five videos are in the same width and height. The second part is the hstack of another 2 videos and the third part is the hstack and vstack of another 3 videos. While concat all the five video parts the aspect ratio is not maintaining in the final video. Since I am new to ffmpeg help me to sort out the problem</p>
  
  <p>I have tried with the command in my final with filter complex and to reduce the size I used frame per second.</p>
  
  <p><code>"ffmpeg -i 
  final.mp4 -vf scale=1280:480 -filter:v fps=fps=30 finalNew.mp4"</code></p>
  
  <p>but nothing worked.
  Also help me to use hstack with scaling, to maintain the aspect ratio for the second part on below command</p>
  
  <blockquote>
    <p>Command: ffmpeg -i vid1.mkv -i vid2.mkv -filter_complex "[0:v]scale=-1:480[v0];[0:v][1:v]hstack=inputs=2"vid3.mkv</p>
  </blockquote>
  
  <p>Images</p>
  
  <p><a href="https://i.stack.imgur.com/m8Smq.png" rel="nofollow noreferrer">second part</a></p>
  
  <p><a href="https://i.stack.imgur.com/qilaJ.png" rel="nofollow noreferrer">third part</a></p>
  
  <p><a href="https://i.stack.imgur.com/9ETdQ.png" rel="nofollow noreferrer">videochunks</a></p>
  
  <p>I have console the info of my video</p>
  
  <p><code>ffmpeg -i part1.mkv -i part2.mkv -i part3.mkv -i part4.mkv -i part5.mkv
  ffmpeg version N-94911-g197985c5bf Copyright (c) 2000-2019 the FFmpeg developers
    built with gcc 9.1.1 (GCC) 20190807
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
    libavutil      56. 35.100 / 56. 35.100
    libavcodec     58. 56.101 / 58. 56.101
    libavformat    58. 32.104 / 58. 32.104
    libavdevice    58.  9.100 / 58.  9.100
    libavfilter     7. 58.102 /  7. 58.102
    libswscale      5.  6.100 /  5.  6.100
    libswresample   3.  6.100 /  3.  6.100
    libpostproc    55.  6.100 / 55.  6.100
  Input #0, matroska,webm, from 'part1.mkv':
    Metadata:
      ENCODER         : Lavf58.32.104
    Duration: 00:00:44.00, start: 0.000000, bitrate: 189 kb/s
      Stream #0:0(eng): Video: h264 (High), yuv420p(progressive), 640x480 [SAR 9:16 DAR 3:4], 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
      Metadata:
        title           : Video
        ENCODER         : Lavc58.56.101 libx264
        DURATION        : 00:00:44.000000000
  Input #1, matroska,webm, from 'part2.mkv':
    Metadata:
      ENCODER         : Lavf58.32.104
    Duration: 00:01:22.07, start: 0.000000, bitrate: 113 kb/s
      Stream #1:0: Video: h264 (High), yuv420p(progressive), 640x240 [SAR 9:16 DAR 3:2], 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
      Metadata:
        ENCODER         : Lavc58.56.101 libx264
        DURATION        : 00:01:22.066000000
  Input #2, matroska,webm, from 'part3.mkv':
    Metadata:
      ENCODER         : Lavf58.32.104
    Duration: 00:00:42.03, start: 0.000000, bitrate: 405 kb/s
      Stream #2:0: Video: h264 (High), yuv420p(progressive), 640x720 [SAR 9:16 DAR 1:2], 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
      Metadata:
        ENCODER         : Lavc58.56.101 libx264
        DURATION        : 00:00:42.033000000
  Input #3, matroska,webm, from 'part4.mkv':
    Metadata:
      ENCODER         : Lavf58.32.104
    Duration: 00:00:21.00, start: 0.000000, bitrate: 298 kb/s
      Stream #3:0: Video: h264 (High), yuv420p(progressive), 640x240 [SAR 9:16 DAR 3:2], 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
      Metadata:
        ENCODER         : Lavc58.56.101 libx264
        DURATION        : 00:00:21.000000000
  Input #4, matroska,webm, from 'part5.mkv':
    Metadata:
      ENCODER         : Lavf58.32.104
    Duration: 00:00:16.00, start: 0.000000, bitrate: 169 kb/s
      Stream #4:0(eng): Video: h264 (High), yuv420p(progressive), 640x480 [SAR 9:16 DAR 3:4], 30 fps, 30 tbr, 1k tbn, 60 tbc (default)
      Metadata:
        title           : Video
        ENCODER         : Lavc58.56.101 libx264
        DURATION        : 00:00:16.000000000</code></p>