[SOLVED] Why is ffmpeg stopping after the first encode when using my bash script?

slinkoff · 04-06-2010, 06:07 PM

I'm trying to create a script that will trawl through a directory structure looking for VOB files, convert them to AVI and place them in a ./converted/ sub-directory of the the original source folder. I've knocked up the script below which appears to work fine when I place an "echo" in front of the actual ffmpeg encode line, I get the output on the screen with ffmpeg finding all the VOB files in the directories and looking to convert them to the correct sub-directory. Yet, when I remove the echo and run the script for real, ffmpeg converts the first file and then stops. No errors. Is this something to do with ffmpeg or a problem with my script below?

Code:

#!/bin/bash
#
#  Define the starting search point:
#
start="/mnt/disk1/toconvert"

#
#  Loop over directories looking for VOB files
#
while read file
do
  DIR=$(dirname "$file")
  if [ ! -d "$DIR/converted" ]
     then
     mkdir "$DIR/converted"
  fi  
  ORIGINAL=`basename "$file" .VOB`
  NEWNAME=${ORIGINAL}.avi
  ffmpeg -i "$file" -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k "$DIR/converted/$NEWNAME"
done < <(find $start \( -iname \*.VOB \))

Thanks for your help

slink

grail · 04-06-2010, 08:10 PM

Hi Slink, maybe you would show us maybe 3 or so lines with the echo output?

Also, you may change the following:

Quote:

ORIGINAL=`basename "$file" .VOB`
NEWNAME=${ORIGINAL}.avi
ffmpeg -i "$file" -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k "$DIR/converted/$NEWNAME"

to

Code:

ffmpeg -i "$file" -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k "$DIR/converted/${file%vob}avi"

Just a suggestion

slinkoff · 04-07-2010, 02:21 AM

sure, here's the output when I run it on 2 test directories containing a total of 3 files, 2 in 1, 1 in the other.

Code:

ffmpeg -i /mnt/disk1/downloads/convert/test/1/VTS_07_1.VOB -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k /mnt/disk1/downloads/convert/test/1/converted/VTS_07_1.avi
ffmpeg -i /mnt/disk1/downloads/convert/test/1/VTS_05_1.VOB -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k /mnt/disk1/downloads/convert/test/1/converted/VTS_05_1.avi
ffmpeg -i /mnt/disk1/downloads/convert/test/2/VTS_05_1.VOB -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k /mnt/disk1/downloads/convert/test/2/converted/VTS_05_1.avi

grail · 04-07-2010, 04:40 AM

So my initial thought is that when the second ffmpeg gets kicked off it buggers up the first one.

So maybe throw && at the end of the command which will wait until each one finishes before progressing.

Guttorm · 04-07-2010, 05:52 AM

ffmpeg does some strange things to stdin. Try piping /dev/null into it, so it doesn't mess up the while loop.

ffmpeg -i "$file" -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k "$DIR/converted/${file%vob}avi" </dev/null

slinkoff · 04-07-2010, 04:37 PM

Quote:

Originally Posted by Guttorm

ffmpeg -i "$file" -f avi -vcodec mpeg4 -b 5000k -g 300 -bf 2 -ab 192k "$DIR/converted/${file%vob}avi" </dev/null

Yep, that does the trick! Thanks. I'm new to scripting, could you briefly explain what that does/how it fixes the problem?

Thanks

phaemon · 07-06-2011, 04:27 AM

I hit this problem yesterday. ffmpeg reads from stdin and therefore reads what the loop is supposed to get, so the loop gets nothing more. There's a site that explains it all, but I can't post it because it's my first post. I'll try with a followup.

---------- Post added 07-06-11 at 09:28 AM ----------

The full explanation (including why this applies to ssh too) is at: http://mywiki.wooledge.org/BashFAQ/089