[FFmpeg-user] How to check if a youtube URL is valid before starting download?
bo.berglund at gmail.com
Fri Jul 9 09:14:28 EEST 2021
On Thu, 08 Jul 2021 15:22:24 -0500, Leo Butler via ffmpeg-user
<ffmpeg-user at ffmpeg.org> wrote:
>> Yet it did not output a finding of "frozen" or similar.
>It did. See the line I highlighted above. All you need to do now is
>something like filter the output of ffmpeg like:
>ffmpeg -i bluearrow.mp4 -vf "freezedetect=n=0.01:d=5" -map 0:v:0 -f null - | grep -q 'lavfi.freezedetect.freeze_start: '
I tested the command using two different video snippets as input (with and
without the blue arrow) and the screen output shows the line:
[freezedetect @ 0x555be8939800] lavfi.freezedetect.freeze_start: 0
for *only* the bluearrow.mp4 video so this is a step forward!
However, the grep command does the same (nothing) in both cases!
I tested by replacing the | grep ... stuff with a redirect to file instead
ffmpeg -hide_banner -i bluearrow.mp4 -vf "freezedetect=n=0.01:d=5" -map 0:v:0 -f
null - > freezeoutput.txt
This showed the same screen output but the freezeoutput.txt file is created but
So grep has no chance of ever detecting anything....
Strange that the ffmpeg execution puts a lot of stuff on screen but nothing
comes out in an output redirect file!!
How can I programmatically check what is shown on screen when it does not reach
Is this what you mean by:
>O! ffmpeg sends stuff to stdout and stderr in random ways, so you will
>need to redirect stderr to stdout, I suspect.
Note that I am testing this in an ssh command line session to the linux box
Developer in Sweden
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