How to concatenate two or more videos with different dimensions in FFMpeg?

I have two videos I would like to concatenate.

1. First Video Dimensions = 480x640
2. Second Video Dimensions = 640x480

I tried concatenating them and received an error. I've included the full error below.

ffmpeg -i 682_segment_0.mp4 -i 682_segment_1.mp4 -filter_complex \
        "[0:v:0] [0:a:0] [1:v:0] [1:a:0] concat=n=2:v=1:a=1 [v] [a]" \
       -map "[v]" -map "[a]" -ar 44100 -vcodec libx264 \
       -strict -2 -acodec aac 682.mp4

ffmpeg version 2.8.8-0ubuntu0.16.04.1 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.2) 20160609
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  libavutil      54. 31.100 / 54. 31.100
  libavcodec     56. 60.100 / 56. 60.100
  libavformat    56. 40.101 / 56. 40.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 40.101 /  5. 40.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.101 /  1.  2.101
  libpostproc    53.  3.100 / 53.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '682_segment_0.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:00:19.30, start: 0.000000, bitrate: 335 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 480x640 [SAR 1:1 DAR 3:4], 219 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 120 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '682_segment_1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:00:09.97, start: 0.000000, bitrate: 568 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 460 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, 3.0, fltp, 104 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
[Parsed_concat_0 @ 0x202dea0] Input link in1:v0 parameters (size 640x480, SAR 1:1) do not match the corresponding output link in0:v0 parameters (480x640, SAR 1:1)
[Parsed_concat_0 @ 0x202dea0] Failed to configure output pad on Parsed_concat_0
Error configuring complex filters.
Invalid argument

I did a bit of checking, and it appears I need to resize one of the videos to be the same size as the other video before I could concatenate it. I'm not sure if that is correct, but I resized it using ffmpeg.

ffmpeg -i 682_segment_0.mp4 -vf scale=640:480 -strict -2 682_segment_0b.mp4

After resizing the 480x640 video to 640x480 I tried the concat command again. And got another error. (I've included the final error here, but not the whole output.)

Input #0 Video Stream: 640x480 [SAR 9:16 DAR 3:4]
Input #1 Video Stream: 640x480 [SAR 1:1 DAR 4:3]

[Parsed_concat_0 @ 0x22cefe0] Input link in1:v0 parameters (size 640x480, SAR 1:1) do not match the corresponding output link in0:v0 parameters (640x480, SAR 9:16)
[Parsed_concat_0 @ 0x22cefe0] Failed to configure output pad on Parsed_concat_0

I found that resizing the DAR allowed me to concat the two videos, but the resized portion of the completed video now has the wrong aspect ratio. I was hoping to basically have "black" on the sides with my resize without cropping the video.

I attached an example here:

Resize DAR command that worked but made aspect ratios wrong:

ffmpeg -i 682_segment_0.mp4 -ar 44100 -vcodec libx264 \ 
       -strict -2 -acodec aac -s 360x480 682_segment_0e.mp4

I am wondering if I should try doing the concat and rescale at the same time, but I am not sure how to do so.

Solution 1:

From the concat filter documentation:

All corresponding streams must have the same parameters in all segments; the filtering system will automatically select a common pixel format for video streams, and a common sample format, sample rate and channel layout for audio streams, but other settings, such as resolution, must be converted explicitly by the user.

You will have to scale and pad (or crop) to make 480x640 fit into 640x480:

ffmpeg -i 480.mp4 -i 640.mp4 -filter_complex \
"[0:v]scale=640:480:force_original_aspect_ratio=decrease,pad=640:480:(ow-iw)/2:(oh-ih)/2[v0]; \
 [v0][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]" \
-map "[v]" -map "[a]" -c:v libx264 -c:a aac -movflags +faststart output.mp4

• Your ffmpeg is old: you should really consider updating to a build from the current git master branch. The easiest way to do that is to just download a binary.

• If you're scripting this then you should "conform" each input to common parameters using fps, format/aformat, and scale filters to avoid ffmpeg from choosing unexpected and undesired "common formats".

• Also see Resizing videos with ffmpeg to fit into static sized player.