Shell script - loop through directories?

Question

If I wanted to loop through a list of nested directories and run a set commands, how would I do that?

My directory structure is like this:

videos
- folder1 -> VTS_01_1.mp4
- folder2 -> VTS_01_1.mp4
- folder3 -> VTS_01_1.mp4 .... and so on

I need to loop through each folder and run the script below.. All of the .mp4 files are named VTS_01_1.mp4, but I'd like to do it with a *.mp4 wildcard condition just incase they aren't. The output file in each directory should be "VTS_01_h264.mp4". Ideas? I'm using CentOS 6.4.

ffmpeg -y -i "VTS_01_1.mp4" -an -pass 1 -threads 2 -vcodec libx264 -b 512k -flags +loop+mv4 -cmp 256 \
       -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 \
       -me_method hex -subq 7 -trellis 1 -refs 5 -bf 3 \
       -flags2 +bpyramid+wpred+mixed_refs+dct8x8 -coder 1 -me_range 16 \
           -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10\
       -qmax 51 -qdiff 4 "video_tmp.mp4"



ffmpeg -y -i "VTS_01_1.mp4" -acodec libfaac -ar 44100 -ab 96k -pass 2 -threads 2 -vcodec libx264 -b 512k -flags +loop+mv4 -cmp 256 \
       -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 \
       -me_method hex -subq 7 -trellis 1 -refs 5 -bf 3 \
       -flags2 +bpyramid+wpred+mixed_refs+dct8x8 -coder 1 -me_range 16 \
           -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10\
       -qmax 51 -qdiff 4 "video_tmp.mp4"



qt-faststart "video_tmp.mp4" "VTS_01_h264.mp4"

There is no reason for you to declare so many options. That's what the x264 presets are for. You can simplify the command to: ffmpeg -y -i input -an -pass 1 -vcodec libx264 -preset slow -b:v 512k -f mp4 /dev/null && ffmpeg -i input -pass 2 -vcodec libx264 -preset slow -b:v 512k -acodec libfaac -ar 44100 -b:a 96k -movflags faststart output.mp4 The first pass output can be sent to /dev/null, -b is ambiguous so you should specify the stream, and you can replace qt-faststart with the -movflags faststart option in the 2nd pass. — llogan
– llogan, Commented Nov 22, 2013 at 19:44

pfnuesel · Accepted Answer · 2013-11-22 15:53:21Z

The find command is very powerful in such things, try:

find videos/ -name "*.mp4" -exec ffmpegScript {} \;

This finds all files (also in subdirectories) with .mp4 as ending and executes ffmpegScript nameOfMp4File, where nameOfMp4File is the name of the file that was found, one at a time. find takes care of the looping itself.

Now we need to define the ffmpegScript:

#!/usr/bin/env bash

inputFile="$1"
outputFile="$(dirname $1)"/VTS_01_h265.mp4

ffmpeg -y -i "$inputFile" -acodec libfaac -ar 44100 -ab 96k -pass 2 -threads 2 -vcodec libx264 -b 512k -flags +loop+mv4 -cmp 256 \
   -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 \
   -me_method hex -subq 7 -trellis 1 -refs 5 -bf 3 \
   -flags2 +bpyramid+wpred+mixed_refs+dct8x8 -coder 1 -me_range 16 \
       -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10\
   -qmax 51 -qdiff 4 "video_tmp.mp4"

qt-faststart "video_tmp.mp4" "$outputFile"

The inputFile variable is set as first positional parameter passed to the ffmpegscript, the outputFile variable is set with the same path, but different basename.

Note: This script will overwrite your output files if there's more than one *.mp4 file in a directory. Also, I didn't try the whole script, since I don't have any *.mp4 files available here.

petrus4 · Accepted Answer · 2013-11-22 17:04:50Z

2

#!/usr/bin/env bash

set -x

#----------+code----------
find *.mp4 -maxdepth 3 -type f | while read files
do
./ffmpeg.sh "${files}"

qt-faststart "${files}_tmp.mp4" "VTS_01_h264.mp4"
done
#----------.code----------

And in ffmpeg.sh:-

#!/usr/bin/env bash

set -x

#----------+code----------
ffmpeg -y -i "${1}" -an -pass 1 -threads 2 -vcodec \
    libx264 -b 512k -flags +loop+mv4 -cmp 256 \
   -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 \
   -me_method hex -subq 7 -trellis 1 -refs 5 -bf 3 \
   -flags2 +bpyramid+wpred+mixed_refs+dct8x8 -coder 1 -me_range 16 \
   -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10\
   -qmax 51 -qdiff 4 "${1}_tmp.mp4"
#----------.code----------

answered Nov 22, 2013 at 17:04

petrus4

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