ffmpeg


How to create a video from thousands of images using ffmpeg

We have this simulation that creates several frames demonstrating the life-cycle of an ant colony.
Having thousands of pictures is not very useful most of the times so we decided to create a video out of those frames.
To do so, we decided to use ffmpeg. The names of the files that we generate are 5 digit zero-leading auto increment numbers (e.g 00001.png and 00002.png) so we ended up with the following command:

ffmpeg -framerate 60 -i %05d.png video.mp4;


How to create a video from an audio file and an image using ffmpeg

Recently, we had this audio file ( mp3) that we wanted to upload to youtube.com. As it is known, youtube does not allow uploading audio files. Taking that into consideration we had to create a video with a static image just to upload the audio file to youtube. To do that, we used ffmpeg and the following command:

ffmpeg -loop 1 -i Saturday.png -i 20181020.mp3 -shortest -acodec copy 20181020.mp4;


How we concatenate multiple mp3 files into one using ffmpeg

Recently, we needed to concatenate multiple mp3 files into one. We had at our disposal a machine that had ffmpeg installed.
To perform the merge, we created a list (separated by the character |) of the mp3 files, in the order we wanted them merged and executed the concat operation of ffmpeg to complete our task. Our resulting command was the following

ffmpeg -i "concat:20181021_080743.MP3|20181021_090745.MP3|20181021_100745.MP3" -acodec copy 20181021.mp3


Qubes 4.0 with Fedora 26: Setup RPM Fusion and ffmpeg

Recently we wanted to process some media on a Fedora 26 running under a Qubes OS 4.0 installation, we decided to use ffmpeg which is not part of the default repositories but it can be found in the RPM Fusion repositories. To do so, first we updated our system and enabled the RPM Fusion repositories as follows:

sudo dnf update;

sudo dnf upgrade -y;

sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm;

sudo dnf config-manager --set-enabled rpmfusion-free rpmfusion-nonfree;

By default DNF on the template VM did not enable the rpmfusion repositories so we had to enable them manually with the last command above or else we would get the following error:

$ sudo dnf install ffmpeg;
Last metadata expiration check: 0:17:49 ago on Tue Oct 16 09:09:22 2018.
No match for argument: ffmpeg

Then, we updated the system once more so that the information from the new repositories would get downloaded to our system and then we performed the installation of ffmpeg. While installing ffmpeg, since it was the first time that we were using the new repositories we were asked to verify the keys that were imported. We were able to manually verify the keys from this page.

The commands used to install ffmpeg are the following:

sudo dnf update;

sudo dnf install ffmpeg;



Fedora 28: Setup RPM Fusion and ffmpeg

Recently we wanted to process some media on a Fedora 28, we decided to use ffmpeg which is not part of the default repositories but it can be found in the RPM Fusion repositories. To do so, first we updated our system and enabled the RPM Fusion repositories as follows:

sudo dnf update;

sudo dnf upgrade -y;

sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm;

Then, we updated the system once more so that the information from the new repositories would get downloaded to our system and then we performed the installation of ffmpeg. While installing ffmpeg, since it was the first time that we were using the new repositories we were asked to verify the keys that were imported. We were able to manually verify the keys from this page.

The commands used to install ffmpeg are the following:

sudo dnf update;

sudo dnf install ffmpeg;

Full Installation Log

[[email protected] ~]$ sudo dnf update
[sudo] password for xeirwn: 
Last metadata expiration check: 1:05:54 ago on Fri 28 Sep 2018 08:48:36 AM EEST.
Dependencies resolved.
Nothing to do.
Complete!
[[email protected] ~]$ sudo dnf upgrade -y
Last metadata expiration check: 1:06:13 ago on Fri 28 Sep 2018 08:48:36 AM EEST.
Dependencies resolved.
Nothing to do.
Complete!
[[email protected] ~]$ sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm
Last metadata expiration check: 1:06:49 ago on Fri 28 Sep 2018 08:48:36 AM EEST.
rpmfusion-free-release-28.noarch.rpm                                      31 kB/s |  20 kB     00:00    
rpmfusion-nonfree-release-28.noarch.rpm                                   41 kB/s |  21 kB     00:00    
Dependencies resolved.
=========================================================================================================
 Package                              Arch              Version            Repository               Size
=========================================================================================================
Installing:
 rpmfusion-free-release               noarch            28-1               @commandline             20 k
 rpmfusion-nonfree-release            noarch            28-1               @commandline             21 k

Transaction Summary
=========================================================================================================
Install  2 Packages

Total size: 41 k
Installed size: 18 k
Is this ok [y/N]: y
Downloading Packages:
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                 1/1 
  Installing       : rpmfusion-nonfree-release-28-1.noarch                                           1/2 
  Installing       : rpmfusion-free-release-28-1.noarch                                              2/2 
  Verifying        : rpmfusion-free-release-28-1.noarch                                              1/2 
  Verifying        : rpmfusion-nonfree-release-28-1.noarch                                           2/2 

Installed:
  rpmfusion-free-release.noarch 28-1                rpmfusion-nonfree-release.noarch 28-1               

Complete!
[[email protected] ~]$ sudo dnf update
RPM Fusion for Fedora 28 - Free - Updates                                152 kB/s | 481 kB     00:03    
RPM Fusion for Fedora 28 - Free                                          195 kB/s | 754 kB     00:03    
RPM Fusion for Fedora 28 - Nonfree - Updates                              59 kB/s |  85 kB     00:01    
RPM Fusion for Fedora 28 - Nonfree                                        72 kB/s | 208 kB     00:02    
Last metadata expiration check: 0:00:00 ago on Fri 28 Sep 2018 09:56:01 AM EEST.
Dependencies resolved.
Nothing to do.
Complete!
[[email protected] ~]$ sudo dnf install ffmpeg
Last metadata expiration check: 0:01:01 ago on Fri 28 Sep 2018 09:56:01 AM EEST.
Dependencies resolved.
=========================================================================================================
 Package               Arch       Version                               Repository                  Size
=========================================================================================================
Installing:
 ffmpeg                x86_64     4.0.2-6.fc28                          rpmfusion-free-updates     1.3 M
Installing dependencies:
 clang5.0-libs         x86_64     5.0.1-3.fc28                          fedora                      12 M
 ffmpeg-libs           x86_64     4.0.2-6.fc28                          rpmfusion-free-updates     6.7 M
 hwloc-libs            x86_64     1.11.9-1.fc28                         fedora                     1.6 M
 libaom                x86_64     1.0.0-3.fc28                          updates                    1.2 M
 libass                x86_64     0.13.4-6.fc28                         updates                    104 k
 libavdevice           x86_64     4.0.2-6.fc28                          rpmfusion-free-updates      94 k
 libclc                x86_64     0.2.0-9.git1cb3fbf.fc27               fedora                     7.9 M
 libmfx                x86_64     1.23-3.fc28                           fedora                      35 k
 llvm5.0-libs          x86_64     5.0.1-7.fc28                          fedora                      15 M
 ocl-icd               x86_64     2.2.12-1.fc28                         fedora                      50 k
 opencl-filesystem     noarch     1.0-6.fc27                            fedora                     7.1 k
 opencore-amr          x86_64     0.1.5-3.fc28                          rpmfusion-free             180 k
 vid.stab              x86_64     1.1-4.20170830gitafc8ea9.fc28         fedora                      50 k
 vo-amrwbenc           x86_64     0.1.3-4.fc28                          rpmfusion-free              77 k
 x264-libs             x86_64     0.152-5.20171224gite9a5903.fc28       rpmfusion-free             575 k
 x265-libs             x86_64     2.7-3.fc28                            rpmfusion-free             1.7 M
 xvidcore              x86_64     1.3.5-1.fc28                          rpmfusion-free             268 k
 zvbi                  x86_64     0.2.35-5.fc28                         fedora                     423 k
Installing weak dependencies:
 beignet               x86_64     1.3.2-2.fc28                          fedora                     4.8 M
 mesa-libOpenCL        x86_64     18.0.5-4.fc28                         updates                    350 k
 pocl                  x86_64     1.1-4.fc28                            updates                     13 M

Transaction Summary
=========================================================================================================
Install  22 Packages

Total download size: 67 M
Installed size: 253 M
Is this ok [y/N]: y
Downloading Packages:
(1/22): libaom-1.0.0-3.fc28.x86_64.rpm                                   250 kB/s | 1.2 MB     00:05    
(2/22): libmfx-1.23-3.fc28.x86_64.rpm                                     63 kB/s |  35 kB     00:00    
(3/22): ocl-icd-2.2.12-1.fc28.x86_64.rpm                                 180 kB/s |  50 kB     00:00    
(4/22): vid.stab-1.1-4.20170830gitafc8ea9.fc28.x86_64.rpm                 58 kB/s |  50 kB     00:00    
(5/22): zvbi-0.2.35-5.fc28.x86_64.rpm                                    192 kB/s | 423 kB     00:02    
(6/22): ffmpeg-4.0.2-6.fc28.x86_64.rpm                                   140 kB/s | 1.3 MB     00:09    
(7/22): vo-amrwbenc-0.1.3-4.fc28.x86_64.rpm                               26 kB/s |  77 kB     00:02    
(8/22): opencore-amr-0.1.5-3.fc28.x86_64.rpm                              15 kB/s | 180 kB     00:12    
(9/22): x264-libs-0.152-5.20171224gite9a5903.fc28.x86_64.rpm              65 kB/s | 575 kB     00:08    
(10/22): xvidcore-1.3.5-1.fc28.x86_64.rpm                                 65 kB/s | 268 kB     00:04    
(11/22): libavdevice-4.0.2-6.fc28.x86_64.rpm                              53 kB/s |  94 kB     00:01    
(12/22): libass-0.13.4-6.fc28.x86_64.rpm                                 141 kB/s | 104 kB     00:00    
(13/22): beignet-1.3.2-2.fc28.x86_64.rpm                                 460 kB/s | 4.8 MB     00:10    
(14/22): x265-libs-2.7-3.fc28.x86_64.rpm                                  87 kB/s | 1.7 MB     00:20    
(15/22): clang5.0-libs-5.0.1-3.fc28.x86_64.rpm                           506 kB/s |  12 MB     00:23    
(16/22): opencl-filesystem-1.0-6.fc27.noarch.rpm                          54 kB/s | 7.1 kB     00:00    
(17/22): ffmpeg-libs-4.0.2-6.fc28.x86_64.rpm                             107 kB/s | 6.7 MB     01:04    
(18/22): hwloc-libs-1.11.9-1.fc28.x86_64.rpm                             343 kB/s | 1.6 MB     00:04    
(19/22): mesa-libOpenCL-18.0.5-4.fc28.x86_64.rpm                         225 kB/s | 350 kB     00:01    
(20/22): llvm5.0-libs-5.0.1-7.fc28.x86_64.rpm                            412 kB/s |  15 MB     00:36    
(21/22): libclc-0.2.0-9.git1cb3fbf.fc27.x86_64.rpm                       544 kB/s | 7.9 MB     00:14    
(22/22): pocl-1.1-4.fc28.x86_64.rpm                                      390 kB/s |  13 MB     00:34    
---------------------------------------------------------------------------------------------------------
Total                                                                    685 kB/s |  67 MB     01:39     
warning: /var/cache/dnf/rpmfusion-free-updates-18aab6236926d6fd/packages/ffmpeg-4.0.2-6.fc28.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 09eab3f2: NOKEY
Importing GPG key 0x09EAB3F2:
 Userid     : "RPM Fusion free repository for Fedora (28) <[email protected]>"
 Fingerprint: 3424 9D2C B375 8B55 48E2 874F C08D 3269 09EA B3F2
 From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-rpmfusion-free-fedora-28
Is this ok [y/N]: y
Key imported successfully
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :                                                                                 1/1 
  Installing       : opencl-filesystem-1.0-6.fc27.noarch                                            1/22 
  Installing       : llvm5.0-libs-5.0.1-7.fc28.x86_64                                               2/22 
  Running scriptlet: llvm5.0-libs-5.0.1-7.fc28.x86_64                                               2/22 
  Installing       : clang5.0-libs-5.0.1-3.fc28.x86_64                                              3/22 
  Installing       : beignet-1.3.2-2.fc28.x86_64                                                    4/22 
  Installing       : libclc-0.2.0-9.git1cb3fbf.fc27.x86_64                                          5/22 
  Installing       : hwloc-libs-1.11.9-1.fc28.x86_64                                                6/22 
  Installing       : pocl-1.1-4.fc28.x86_64                                                         7/22 
  Installing       : mesa-libOpenCL-18.0.5-4.fc28.x86_64                                            8/22 
  Running scriptlet: mesa-libOpenCL-18.0.5-4.fc28.x86_64                                            8/22 
  Installing       : ocl-icd-2.2.12-1.fc28.x86_64                                                   9/22 
  Running scriptlet: ocl-icd-2.2.12-1.fc28.x86_64                                                   9/22 
  Installing       : libass-0.13.4-6.fc28.x86_64                                                   10/22 
  Installing       : xvidcore-1.3.5-1.fc28.x86_64                                                  11/22 
  Installing       : x265-libs-2.7-3.fc28.x86_64                                                   12/22 
  Installing       : x264-libs-0.152-5.20171224gite9a5903.fc28.x86_64                              13/22 
  Running scriptlet: x264-libs-0.152-5.20171224gite9a5903.fc28.x86_64                              13/22 
  Installing       : vo-amrwbenc-0.1.3-4.fc28.x86_64                                               14/22 
  Running scriptlet: vo-amrwbenc-0.1.3-4.fc28.x86_64                                               14/22 
  Installing       : opencore-amr-0.1.5-3.fc28.x86_64                                              15/22 
  Running scriptlet: opencore-amr-0.1.5-3.fc28.x86_64                                              15/22 
  Installing       : zvbi-0.2.35-5.fc28.x86_64                                                     16/22 
  Running scriptlet: zvbi-0.2.35-5.fc28.x86_64                                                     16/22 
  Installing       : vid.stab-1.1-4.20170830gitafc8ea9.fc28.x86_64                                 17/22 
  Running scriptlet: vid.stab-1.1-4.20170830gitafc8ea9.fc28.x86_64                                 17/22 
  Installing       : libmfx-1.23-3.fc28.x86_64                                                     18/22 
  Running scriptlet: libmfx-1.23-3.fc28.x86_64                                                     18/22 
  Installing       : libaom-1.0.0-3.fc28.x86_64                                                    19/22 
  Installing       : ffmpeg-libs-4.0.2-6.fc28.x86_64                                               20/22 
  Running scriptlet: ffmpeg-libs-4.0.2-6.fc28.x86_64                                               20/22 
  Installing       : libavdevice-4.0.2-6.fc28.x86_64                                               21/22 
  Running scriptlet: libavdevice-4.0.2-6.fc28.x86_64                                               21/22 
  Installing       : ffmpeg-4.0.2-6.fc28.x86_64                                                    22/22 
  Running scriptlet: ffmpeg-4.0.2-6.fc28.x86_64                                                    22/22 
  Verifying        : ffmpeg-4.0.2-6.fc28.x86_64                                                     1/22 
  Verifying        : ffmpeg-libs-4.0.2-6.fc28.x86_64                                                2/22 
  Verifying        : libaom-1.0.0-3.fc28.x86_64                                                     3/22 
  Verifying        : libmfx-1.23-3.fc28.x86_64                                                      4/22 
  Verifying        : ocl-icd-2.2.12-1.fc28.x86_64                                                   5/22 
  Verifying        : vid.stab-1.1-4.20170830gitafc8ea9.fc28.x86_64                                  6/22 
  Verifying        : zvbi-0.2.35-5.fc28.x86_64                                                      7/22 
  Verifying        : opencore-amr-0.1.5-3.fc28.x86_64                                               8/22 
  Verifying        : vo-amrwbenc-0.1.3-4.fc28.x86_64                                                9/22 
  Verifying        : x264-libs-0.152-5.20171224gite9a5903.fc28.x86_64                              10/22 
  Verifying        : x265-libs-2.7-3.fc28.x86_64                                                   11/22 
  Verifying        : xvidcore-1.3.5-1.fc28.x86_64                                                  12/22 
  Verifying        : libavdevice-4.0.2-6.fc28.x86_64                                               13/22 
  Verifying        : libass-0.13.4-6.fc28.x86_64                                                   14/22 
  Verifying        : beignet-1.3.2-2.fc28.x86_64                                                   15/22 
  Verifying        : clang5.0-libs-5.0.1-3.fc28.x86_64                                             16/22 
  Verifying        : llvm5.0-libs-5.0.1-7.fc28.x86_64                                              17/22 
  Verifying        : opencl-filesystem-1.0-6.fc27.noarch                                           18/22 
  Verifying        : pocl-1.1-4.fc28.x86_64                                                        19/22 
  Verifying        : hwloc-libs-1.11.9-1.fc28.x86_64                                               20/22 
  Verifying        : mesa-libOpenCL-18.0.5-4.fc28.x86_64                                           21/22 
  Verifying        : libclc-0.2.0-9.git1cb3fbf.fc27.x86_64                                         22/22 

Installed:
  ffmpeg.x86_64 4.0.2-6.fc28                                  beignet.x86_64 1.3.2-2.fc28                
  mesa-libOpenCL.x86_64 18.0.5-4.fc28                         pocl.x86_64 1.1-4.fc28                     
  clang5.0-libs.x86_64 5.0.1-3.fc28                           ffmpeg-libs.x86_64 4.0.2-6.fc28            
  hwloc-libs.x86_64 1.11.9-1.fc28                             libaom.x86_64 1.0.0-3.fc28                 
  libass.x86_64 0.13.4-6.fc28                                 libavdevice.x86_64 4.0.2-6.fc28            
  libclc.x86_64 0.2.0-9.git1cb3fbf.fc27                       libmfx.x86_64 1.23-3.fc28                  
  llvm5.0-libs.x86_64 5.0.1-7.fc28                            ocl-icd.x86_64 2.2.12-1.fc28               
  opencl-filesystem.noarch 1.0-6.fc27                         opencore-amr.x86_64 0.1.5-3.fc28           
  vid.stab.x86_64 1.1-4.20170830gitafc8ea9.fc28               vo-amrwbenc.x86_64 0.1.3-4.fc28            
  x264-libs.x86_64 0.152-5.20171224gite9a5903.fc28            x265-libs.x86_64 2.7-3.fc28                
  xvidcore.x86_64 1.3.5-1.fc28                                zvbi.x86_64 0.2.35-5.fc28                  

Complete!

ffmpeg: Create a video countdown

The code below was used to generate the video countdown timers that are available in the following playlist using ffmpeg:

#This example will create a 3 second video, with 100 frames per second and it will print the elapsed and remaining times using a two second accuracy.
fps=100;
seconds=3;
mantissaDigits=2;
upperFont=600;
lowerFont=100;
ffmpeg -loop 1 -i ~/Pictures/Black-Background.png -c:v libx264 -r $fps -t $seconds -pix_fmt yuv420p -vf "fps=$fps,drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$upperFont:x=(w-text_w)/2:y=(h-text_h)/2:text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}',drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf':fontcolor=yellow:fontsize=$lowerFont:x=(w-text_w)/2:y=((h-text_h)/2)+$upperFont:text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}'" "$seconds seconds countdown timer.mp4";

Notes:

  • We used a single black frame for the background that defined the size of the video frame as well.
  • Using the fps variable we defined the number of Frames per Second for the video.
  • The seconds variable defined the number of seconds the duration of the video should be.
  • The mantissaDigits variable defines how many decimal digits should be shown after the dot.
  • upperFont and lowerFont define the size of the fonts in the upper row and the lower one respectively.
  • We used the drawtext directive twice to write to the frames.

Notes on the first drawtext:

  • fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$upperFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=(h-text_h)/2 defines the Y-coordinate of the location for the text on the frame, here we center the text vertically on the frame.
  • text='%{eif\:($seconds-t)\:d}.%{eif\:(mod($seconds-t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the remaining seconds for the video to finish with specific decimal digit accuracy.

Notes on the second drawtext:

  • drawtext=fontfile='/usr/share/fonts/urw-base35/C059-Bold.otf' defines the font to be used for the text.
  • fontcolor=yellow defines the color of the font of the text.
  • fontsize=$lowerFont defines the size of the font of the text.
  • x=(w-text_w)/2 defines the X-coordinate of the location for the text on the frame, here we center the text horizontally on the frame.
  • y=((h-text_h)/2)+$upperFont defines the Y-coordinate of the location for the text on the frame, here shift the text from the vertical center  of the frame.
  • text='Elapsed\: %{eif\:(t)\:d}.%{eif\:(mod(t, 1)*pow(10,$mantissaDigits))\:d\:$mantissaDigits}' We print the elapsed seconds since the video started with specific decimal digit accuracy.

ffmpeg: Extract audio from .MKV to .MP3 6

The following command will find all mkv files that are in the current directory and in all sub-folders and extract the audio to mp3 format.

find . -type f -name "*.mkv" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -c:a libmp3lame -y "${FILE%.mkv}.mp3";' _ '{}' \;

The filename of the audio file will be the same as the mkv video with the correct extension. The mkv extension will be removed and replaced by the mp3 extension e.g hi.mkv will create a new file named hi.mp3


Bash/FFMPEG: Batch resize .mp4 videos to fixed resolution

We needed to shrink a bunch of mp4 videos so that they would have the same size as the screen of an android device.
We did that both to save space on the internal memory of the device and to make the device perform as efficient as possible as it would not have to shrink the video on the fly.

The command we used was the following:

find . -type f -name "*.mp4" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -s 1280x720 -acodec copy -y "${FILE%.mp4}.shrink.mp4";' _ '{}' \;

What this command does is the following:

  • Find all files in current folder (and sub-folders) that have the extension .mp4
  • For each file, create a new bash instance in which it will call ffmpeg taking as first parameter the filename that matched
  • -i "${FILE}"ffmpeg will take as input the filename we matched
  • -s 1280x720 – Then change the video size to 1280x720
  • -acodec copy – It will keep the audio as is
  • -y "${FILE%.mp4}.shrink.mp4 – Finally, create a new file (or overwrite existing) that has the extension .shrink.mp4 in the same folder

Windows with ffmpeg — recursively convert all *.mov movies to .mp4. with fixed resolution for android 1

We needed to convert a bunch of mov files to mp4 and while doing that we wanted to shrink them down so that they would fit the screen of an older android device.
We did that both to save space on the internal memory and to make the device perform as efficient as possible as it would not have to shrink the video on the fly.

We downloaded the windows binary for ffmpeg from https://ffmpeg.org/ and copied it to the folder we wanted to execute the command from using Windows Explorer.
After that, while holding the Shift key we right clicked in the Windows Explorer empty area to popup the menu. From the menu we selected Open command window here, that opened a Command Prompt that was already navigated in the folder we placed the binary.
To convert the movies we executed the following:

for /R %f in ("*.mov") do (ffmpeg.exe -i "%~f" -s 864x486 -acodec copy "%~pf%~nf.mp4")

What the above command did was, direct command prompt to find recursively all the files that their name ends in .mov (this is the part that looks like this for /R %f in ("*.mov")) and then execute for each a command, in our case was to convert the file to mp4, resize the video while preserving the audio as is and produce a new file that has the same name but different file extension so that new files will have the mp4 extension instead of mov.


ffmpeg: Extract audio from .MP4 to .MP3

The following command will find all mp4 files that are in the current directory and in all sub-folders and extract the audio to mp3 format.

find . -type f -iname "*.mp4" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -y "${FILE%.mp4}.mp3";' _ '{}' \;

The filename of the audio file will be the same as the mp4 video with the correct extension. The mp4 extension will be removed and replaced by the mp3 extension e.g hi.mp4 will become hi.mp3