Trim MV4 Files, Front and Back - Batch

[poleary200]

I have a few thousand files from my conversion of Super 8 tapes to digital. The files are now presently all in M4V format. When the videos were shot, each clip in the video has a Fade In and a Fade Out applied. I want to trim the Fade In (0 to 6 seconds in every file) and the Fade Out (End-6 to End). I've looked into many options including searching on this forum, but just can't figure out what I need. I have access to both Mac and Windows, thus either option would work.

Thoughts?

[Baldrick]

Probably easiest with ffmpeg

for %%a in ("*.mv4") do ffmpeg -i "%%a" -ss 6 -vcodec copy -acodec copy "newfiles\%%~na.mp4"

To trim 6 seconds from the beginning in all mv4 files and creates new mp4 files.

But it's seems to be much more difficult to trim the end. See https://forum.videohelp.com/threads/348879-Trimming-video-from-it-s-end-using-FFMpeg-or-Mencoder


ffmpeg batch guide
https://forum.videohelp.com/threads/356314-How-to-batch-convert-multiplex-any-files-with-ffmpeg

[poleary200]

I'm trying your approach for the front of the video first. I have the .bat file setup, ffmpeg.exe in the same folder, newfiles folder set. When i run the bat, it just flashes and nothing happens.

[poisondeathray]

are you sure they are ".mv4", not ".m4v" ? It says mv4 in the title and the batch file, but the 1st post says M4V . Typo ?

add "pause" (without quotes) to the end of the batch file to see error messages

[Baldrick]

add pause to the end of the bat file like

for %%a in ("*.mv4") do ffmpeg -i "%%a" -ss 6 -vcodec copy -acodec copy "newfiles\%%~na.mp4"
pause

and you will see the error message

[poleary200]

The files are M4V as mentioned previously. ??

[Baldrick]

Then change to m4v

for %%a in ("*.m4v") do ffmpeg -i "%%a" -ss 6 -vcodec copy -acodec copy "newfiles\%%~na.mp4"
pause

[poleary200]

Oh. I see in your code you put MV4. My current files are M4V. With ffmpeg, can this be done without reencoding everything? Instead of writing to an mp4 file, just keep it M4V?

[Baldrick]

Nothing is reencoded when you use -vcodec copy and -acodec copy.

mp4 = m4v.

[poleary200]

OK thanks. I'll try it out. Then, work on the end portion. Thanks.

[poleary200]

That worked incredibly well. Thanks so much. Testing out the end portion now.

[poleary200]

Based on what i have read, you have to use ffprobe to determine the duration. Then, subtract the end point from the duration to get the end point.

I tried this, but no dice.


for %%a in ("*.m4v") do ffmpeg -i "%%a" -t ffprobe "filename" -6 vcodec copy -acodec copy "newfiles\%%~na.mp4"

[Baldrick]

It's complex. You should use ffprobe to read the length and then use it in the bat....I can try later tonight.

[poleary200]

Any help you can lend is certainly appreciated. As you can imagine, I'm not even close to a coder. I'm just Googling and trying things to see what works.

I found this code that is supposed to give you the Duration in seconds. But I can't figure out how to get it into the BAT loop.

$(ffprobe  "$INPUT_FILE" 2>&1 | grep Duration: |  \
        cut -f3,4 -d: | cut -f1 -d,);

[Baldrick]

grep and cut wont work in windows.

[poleary200]

It's complex. You should use ffprobe to read the length and then use it in the bat....I can try later tonight.

Hi there. Was wondering if you have ever tried this or you could take a look? I would be very grateful. I cannot figure out the batch trim on the end.

[poleary200]

The other thing is...it doesn't have to be a trim. It could be a split of files 6 seconds from the end of each file. Then, I'll just delete the small files. Thoughts?

[Baldrick]

I tried and gave up. .

[poleary200]

The effort is still appreciated!!!

I did find this code online for Mac. Problem is, it doesn't work under Mavericks. If there is anyone that knows anything about it...I'd love to figure this out!!!

set secondsFromStart to 6
set secondsFromEnd to 6
set shortMoviesList to {}

set srcFolder to choose folder

tell application "Finder"
set fileList to files of folder srcFolder
repeatwith f in fileList
tell application "QuickTime Player"
           open f
tell document 1
-- Check to make sure we're not trimming more time than the movie contains
set timeScale to timescale
set trimmedTime to (timeScale * (secondsFromStart + secondsFromEnd))
if trimmedTime isgreater than duration then
-- Not enough content to trim, add file name to a list
setendof shortMoviesList to (the name of f as string) & return
else
-- We have enough content, proceed to trimming
set selection start to (timeScale * secondsFromStart)
set selection endto (duration - (timeScale * secondsFromEnd))
                   trim
                   save
endif
               close
endtell
endtell
endrepeat
if length of shortMoviesList isgreater than 0 then
tell application "Finder"
-- bring Finder to front so dialog is not hidden
           activate
endtell
       display dialog "The following movies could not be trimmed because they do not contain enough content: " & return& return & shortMoviesList with icon caution
endif
endtell

[poleary200]

OK, I got it. It only works on a Mac. And it only works with MP4 files. I struggled with this for the longest time. I kept receiving permission issues. Turns out, for some reason the Quicktime / Applescript would NOT work with an M4V. I converted my files to MP4 and voila, the code to trim works out perfectly. It is below.

set secondsFromStart to 3.5
set secondsFromEnd to 3.5
set srcFolder to choose folder
set dstFolder to choose folder with prompt "Choose the destination folder for the trimmed files." default location srcFolder


tell application "Finder"
    set fileList to files of folder srcFolder
end tell




repeat with f in fileList
    tell application "QuickTime Player"
        open f
        set documentName to name of f
        delay (1.0)
        tell document 1
            if duration > 7 then
                trim from secondsFromStart to (duration - secondsFromEnd)
                            
                export in file ((dstFolder as text) & documentName) using settings preset "480p..."
                close saving no
                delay (1.0)
            else
                close saving no
                delay (1.0)
            end if
        end tell
    end tell
end repeat