yt-dlp command to extract a video in slowmotion

[pib]

Hello

I would like to know if is there any yt-dlp command to extract a video (say from youtube) and convert it into slowmotion.

Thank you very much in advance for any help!

Pib

[Hoser Rob]

QUick search says no. WHich I expected, I'd be very surprised if any streaming downloader did this.

[jack_666]

I would like to know if is there any yt-dlp command to extract a video (say from youtube) and convert it into slowmotion.

You need to download the video and then use ffmpeg to implement the speed change


read here


https://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video

[pib]

Thank you guys for the prompt reply!
I managed to do a version for windows system but using temporary files.
I would like to do it via web with no temp files. I guess i will have to use pipes stdin and stdout and multiple/sequential commands.
It won't be easy that's why i would like some help.

[jagabo]

The basic format for piping yt-dlp to ffplay is:

yt-dlp "https://path/to/video" -o - | "x:\path\to\ffplay.exe" -

It should be easy to modify that to pipe to ffmpeg. But I believe remuxing with modified timecodes requires a demux to an elementary stream (to lose the original timecodes), then a remux of that ES with new timecodes.

[pib]

Thank you jagabo for the help!

I managed to get the solution in linux bash command like this:
yt-dlp -i "https://www.youtube.com/watch?v=UT5F9AXjwhg" -f 22 -o - | ffmpeg -i - -vsync 0 -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=(1/2.0)[a]" -map "[v]" -map "[a]" "slow.mp4"

I also went further and managed to get the slowmotion of a partial video extracted like this:
yt-dlp -i "https://www.youtube.com/watch?v=UT5F9AXjwhg" --download-sections "*30-45" -f 22 -o - | ffmpeg -i - -vsync 0 -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=(1/2.0)[a]" -map "[v]" -map "[a]" "slow.mp4"

Now i will use the passthru command of PHP to output the result to the browser

Finally, I will have to extract a part of the video and then concatenate with the slowmotion of that part (using only pipes, without temporary files). Any ideias?

[pib]

Hello again

To convert to slow motion in bash shell I managed like this
yt-dlp -f 22 -i "https://www.youtube.com/watch?v=SIX4-JQkLEU" --download-sections "*1:30-2:00" -o - | ffmpeg -i pipe:0 -vsync 0 -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=(1/2.0)[a]" -map "[v]" -map "[a]" "slow.mp4"

Somehow, the pipe to ffmpeg does not seem to be working in the web server
I already tried many ways but so far no luck :\The last was was like this:

$cmd="yt-dlp -f 22 -i \"https://www.youtube.com/watch?v=SIX4-JQkLEU\" --download-sections \"*1:30-2:00\" -o - | ffmpeg -i pipe:0 -vsync 0 -filter_complex \"[0:v]setpts=2.0*PTS[v];[0:a]atempo=(1/2.0)[a]\" -map \"[v]\" -map \"[a]\" -f mp4 pipe:1";

and then with PHP passtru command i would do the follwing:
$get_video=passthru($cmd);

I always get a corrupt file with 16bytes :\
I looked at the server logs and I didn't find anything :\
What might be wrong above?

I would appreciate any single help

Thank you in advance
pib

[pib]

I managed to find out!
I just had to replace mp4 by mpgets at the end of the command.

[pib]

Another question please. I want to duplicate mp4 video.

In command line I issue the following command:
ffmpeg -i input.mp4 -i input.mp4 -filter_complex "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1" -vsync vfr output.mp4

I was trying the following in web environment:
... -o - | ffmpeg -i pipe:0 -i pipe:0 -filter_complex \"[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1\" -vsync vfr -f mpgets pipe:1";

It does not give any error but it does not duplicate video. What might be wrong?
Can anybody give me an hint?

[pib]

Hello

Before I could use YT-dlp to download facebook reels but since the biginning of this month I can't download facebook reels using Yt-dlp.
Anyone knows what has changed? Maybe in facebook video format, no?
I would appreciate any help
Thank you very much in advance.

Pib