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• ffmpeg how to vertically rotate and concat/stack two videos in one command ?

  3 juin 2022, par baziorek

  I have two recordings inside.MOV and outside.MOV recorded with two cameras (the same settings and the same model).

  


  ---

  


  I want to do something like that :

  


  ffmpeg -i inside.MOV -vf "transpose=2,transpose=2" inside_rotated180degree.MOV # rotate 180 degree
ffmpeg -i outside.MOV -i inside_rotated180degree.MOV \
  -filter_complex "[0:v]scale=640:-1[v0];[v0][1:v]vstack=inputs=2" inside_and_outside.MOV # concat them


  


  but in single command.

  


  I've managed to rotate upper video, but I need to rotate lower :

  


  ffmpeg -i outside.MOV -i inside_rotated180degree.MOV \
  -filter_complex "[0:v]scale=1920:-1,rotate=PI[v0];[v0][1:v]vstack=inputs=2" inside_and_outside.MOV


  


  ---

  


  I tried to modify the command various ways to add rotate=PI, but always there is a error in command/screen/input/... does anybody knows how to rotate video lower instead of upper ?

  


• PowerShell and ffmpeg : No such file or directory

  8 juillet 2022, par Matt Wilson

  I'm trying to use the below command in a Python script, however I'm seeing that it's a PowerShell issue in that it can't seem to find the video file I'm pointing to.

  


  I have a video file on a cloud drive Z: at the following location (for reproducibility, change this to whatever path you want with a video file in it) :

  


  Z:\Udemy_And_Misc_Downloads\TensorFlow Developer Certificate in 2021 Zero to Mastery\3. Neural network regression with TensorFlow\18. Setting up TensorFlow modelling experiments part 2 (increasing complexity).mp4

  


  Notice the spaces and special characters in the filename in case that matters.

  


  What I'm trying to do is down-sample that video file to a smaller size with the following command :

  


  ffmpeg -i "Z:\Udemy_And_Misc_Downloads\TensorFlow Developer Certificate in 2021 Zero to Mastery\[TutsNode.com] - TensorFlow Developer Certificate in 2021 Zero to Mastery\3. Neural network regression with TensorFlow\18. Setting up TensorFlow modelling experiments part 2 (increasing complexity).mp4" -y -vcodec libx264 -acodec ac3 -threads 1 "Z:\Udemy_And_Misc_Downloads\TensorFlow Developer Certificate in 2021 Zero to Mastery\[TutsNode.com] - TensorFlow Developer Certificate in 2021 Zero to Mastery\3. Neural network regression with TensorFlow\18. Setting up TensorFlow modelling experiments part 2 (increasing complexity)DOWNSAMPLED.mp4"

  


  I know it's long as it's mostly consumed by the filenames, but the error I'm getting is :

  


  Z:\Udemy_And_Misc_Downloads\TensorFlow Developer Certificate in 2021 Zero to Mastery\[TutsNode.com] - TensorFlow  Developer Certificate in 2021 Zero to Mastery\3. Neural network regression with TensorFlow\18. Setting up TensorFlow  modelling experiments part 2 (increasing complexity).mp4: No such file or directory

  


  The path IS correct, as it's a direct copy paste from the folder's URL bar.

  


  The things I've tried include :

  


  

  • using quotes around filename

  


  • not using quotes around filename

  


  • prepending quoted filename with "r" (where I got message saying `did you mean file:r ?)

  


  • prepending quoted filename with "file:r"

  


  • used double slashes \ in filepaths

  


  


  Is there a powershell pro out there that can tell me why it can't "find" the file ?

  


  UPDATE
The command runs if I find a filename with :

  


  $oldvids = Get-ChildItem *.mp4, *mov, *wmv, *avi -Recurse
foreach ($oldvid in $oldvids) 
{
    $newvid = [io.path]::ChangeExtension($oldvid.FullName, '_.mp4')
    ffmpeg -i $oldvid.FullName -y -vcodec libx264 -acodec ac3 -threads 1 $newvid
}


  


  When I print the $oldvid.name and $oldvid.FullName, the paths/filenames look like this :

  


  Z:\Udemy_And_Misc_Downloads\TensorFlow Developer Certificate in 2021 Zero to Mastery\5. Computer Vision and Convolutional Neu
ral Networks in TensorFlow\35. Multi-class CNN's part 9 Making predictions with our model on custom images.mp4

35. Multi-class CNN's part 9 Making predictions with our model on custom images.mp4


  


  ...that first one being an exact copy of what I'm trying to use in my posted code. So what's the difference ??

  


  SECOND UPDATE
I think the issue lies in that the file is located on a drive other than C:. Just tested it by moving the file onto my computer and running the command, and it worked. So I guess, is there a way to tell PowerShell to use the Z: drive to find the file ?

  


• ffmpeg - how to handle video and audio URL's streams separately ?

  13 mai 2022, par Rubem Pacelli

  I am trying to create a zsh function that uses youtube-dl and ffmpeg to download a portion of a YouTube video. I did achieve this goal with the following function :

  


  # $1 - youtube URL
# $2 - start position in hh:mm:ss.msms format (ms=miliseconds)
# $3 - final position in hh:mm:ss.msms format (ms=miliseconds)
# $4 - output file name (optional)
function youtubedl_snippet()(
  local url_stream=$(youtube-dl -f best --get-url $1)
  local output_name=$(youtube-dl --get-title $1)

  ffmpeg -ss $2 -to $3 -i $url_stream -c:v copy -c:a copy ${4:-"$output_name.mp4"}
)


  


  The command youtube-dl -f best --get-url $1 return a single URL with the best possible quality. In order to understand better how ffmpeg works, I tried to create another function with the same goal but with a different approach :

  


  # $1 - youtube URL
# $2 - start position in hh:mm:ss.msms format (ms=miliseconds)
# $3 - final position in hh:mm:ss.msms format (ms=miliseconds)
# $4 - output file name (optional)
# $5 - output video codec type (optional, for instance: libx264)
# $6 - output audio codec type (optional, for instance: aac)
function youtubedl_snippet2()(
  local url_streams=$(youtube-dl --get-url $1)
  local output_name=$(youtube-dl --get-title $1)

  local url_array=(${(f)url_streams}) # expand urls by lines url_array[1] -> video stream url_array[2] -> audio stream

  ffmpeg -ss $2 -to $3 -i ${url_array[1]} -ss $2 -to $3 -i ${url_array[2]} -map 0:v -map 1:a -c:v ${5:-copy} -c:a ${6:-copy} ${4:-"$output_name.mp4"}
)


  


  What I suppose that is going on here :

  


  

  1. url_streams is a line-separated URL. url_array[1] is the video URL and url_array[2] is the audio URL.

  


  2. I am setting both audio and video to the same intervals.

  


  3. I mapped the first stream to video, and the second to audio

  


  4. If $5 and $6 does not give different codecs, ffmpeg just copy from the original source.

  


  


  Well, it seems that everything is ok. But when I try

  


  start=$SECONDS; youtubedl_snippet2 'https://www.youtube.com/watch?v=g-_hVXzkn0o' 00:00:05.00 00:00:15.00; echo "it takes $(( SECONDS - start )) seconds"


  


  It will take 368 seconds. Moreover, I cannot open it in my android (only audio works)

  


  

  


  On the other hand,

  


  start=$SECONDS; youtubedl_snippet 'https://www.youtube.com/watch?v=g-_hVXzkn0o' 00:00:05.00 00:00:15.00; echo "it takes $(( SECONDS - start )) seconds"


  


  takes only 40 seconds, and the video can be played on Android.

  


  Here is the youtubedl_snippet log file. And here is the youtubedl_snippet2 log file.