Shell Script and FFMpeg

[angelvg]

Greetings,
I'm working on a script that will perform a transcode using FFMpeg, and I'm encountering some strange behavior.

Location

$ pwd


/tmp/test

The script.sh

$ cat script.sh


#!/bin/sh

WORKDIR='/tmp/test'

cd "${WORKDIR}" || exit 1

# Bucle
while read -r FILENAME; do

  if [ -e ./"${FILENAME}" ]; then

    echo "Transcoding ${FILENAME}. . ."
    ffmpeg -y -hide_banner -i "${FILENAME}" -c:a libvorbis -ar 44100 "${FILENAME}".ogg

  else

    echo "File ${FILENAME} not found"

  fi

done < ./list.txt
exit 0

The list.txt content

$ cat list.txt


file1.wav
file2.wav
file3.wav

Run the script

$ ./script.sh


The output

Transcoding file1.wav. . .
[aist#0:0/pcm_s16le @ 0x2ad11385a300] Guessed Channel Layout: mono
Input #0, wav, from 'file1.wav':
  Duration: 00:00:12.53, bitrate: 768 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels, s16, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, ogg, to 'file1.wav.ogg':
  Metadata:
    encoder         : Lavf60.16.100
  Stream #0:0: Audio: vorbis, 44100 Hz, mono, fltp
    Metadata:
      encoder         : Lavc60.31.102 libvorbis
[out#0/ogg @ 0x2ad113858340] video:0kB audio:103kB subtitle:0kB other streams:0kB global headers:3kB muxing overhead: 4.170636%
size=     107kB time=00:00:12.50 bitrate=  69.9kbits/s speed= 166x   
File ile2.wav not found
Transcoding file3.wav. . .
[aist#0:0/pcm_s16le @ 0x2f629be5a300] Guessed Channel Layout: mono
Input #0, wav, from 'file3.wav':
  Duration: 00:00:12.53, bitrate: 768 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels, s16, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, ogg, to 'file3.wav.ogg':
  Metadata:
    encoder         : Lavf60.16.100
  Stream #0:0: Audio: vorbis, 44100 Hz, mono, fltp
    Metadata:
      encoder         : Lavc60.31.102 libvorbis
[out#0/ogg @ 0x2f629be58340] video:0kB audio:103kB subtitle:0kB other streams:0kB global headers:3kB muxing overhead: 4.170636%
size=     107kB time=00:00:12.50 bitrate=  69.9kbits/s speed= 166x

The result of run the script

$ ls *.ogg


file1.wav.ogg    file3.wav.ogg

The error is in the file called 'file2.wav'

File ile2.wav not found

I don't understand why FFMpeg in the second file cuts off the initial 'f' from the name...

The list.txt file has no strange characters, I have checked it several times and even created it from the 'vi' editor.

I'm using the default shell


$ echo $SHELL


/bin/sh

Thanks for your advice in advance.

 

[cracauer@]

Try running it as `sh -x script.sh` to see more of what's going on.

 

[angelvg]

New information:

If I put a line between the names on the list, it works...


$ cat list.txt


file1.wav

file2.wav

file3.wav

The result

$ ls *.ogg


file1.wav.ogg    file2.wav.ogg    file3.wav.ogg

 

[angelvg]

Try running it as `sh -x script.sh` to see more of what's going on.


$ cat list.txt


file1.wav
file2.wav
file3.wav


$ sh -x ./script.sh


+ WORKDIR=/tmp/test
+ cd /tmp/test
+ read -r FILENAME
+ [ -e ./file1.wav ]
+ echo 'Transcoding file1.wav. . .'
Transcoding file1.wav. . .
+ ffmpeg -y -hide_banner -i file1.wav -c:a libvorbis -ar 44100 file1.wav.ogg
[aist#0:0/pcm_s16le @ 0x3b02685a300] Guessed Channel Layout: mono
Input #0, wav, from 'file1.wav':
  Duration: 00:00:12.53, bitrate: 768 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels, s16, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, ogg, to 'file1.wav.ogg':
  Metadata:
    encoder         : Lavf60.16.100
  Stream #0:0: Audio: vorbis, 44100 Hz, mono, fltp
    Metadata:
      encoder         : Lavc60.31.102 libvorbis
[out#0/ogg @ 0x3b026858340] video:0kB audio:103kB subtitle:0kB other streams:0kB global headers:3kB muxing overhead: 4.170636%
size=     107kB time=00:00:12.50 bitrate=  69.9kbits/s speed= 166x   
+ read -r FILENAME
+ [ -e ./ile2.wav ]
+ echo 'File ile2.wav not found'
File ile2.wav not found
+ read -r FILENAME
+ [ -e ./file3.wav ]
+ echo 'Transcoding file3.wav. . .'
Transcoding file3.wav. . .
+ ffmpeg -y -hide_banner -i file3.wav -c:a libvorbis -ar 44100 file3.wav.ogg
[aist#0:0/pcm_s16le @ 0x22a31085a300] Guessed Channel Layout: mono
Input #0, wav, from 'file3.wav':
  Duration: 00:00:12.53, bitrate: 768 kb/s
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 1 channels, s16, 768 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> vorbis (libvorbis))
Press [q] to stop, [?] for help
Output #0, ogg, to 'file3.wav.ogg':
  Metadata:
    encoder         : Lavf60.16.100
  Stream #0:0: Audio: vorbis, 44100 Hz, mono, fltp
    Metadata:
      encoder         : Lavc60.31.102 libvorbis
[out#0/ogg @ 0x22a310858340] video:0kB audio:103kB subtitle:0kB other streams:0kB global headers:3kB muxing overhead: 4.170636%
size=     107kB time=00:00:12.50 bitrate=  69.9kbits/s speed= 167x   
+ read -r FILENAME
+ exit 0


$ ls *.ogg


file1.wav.ogg    file3.wav.ogg

 

[angelvg]

I'm thinking the problem is with FFMpeg, since if I modify the script to perform a touch, it does so without errors...

The script (only touch)

#!/bin/sh

WORKDIR='/tmp/test'

cd "${WORKDIR}" || exit 1

# Bucle
while read -r FILENAME; do

  if [ -e ./"${FILENAME}" ]; then

    touch ./"${FILENAME}".txt

  else

    echo "File ${FILENAME} not found"

  fi

done < ./list.txt
exit 0

The result

$ ls *.wav.txt


file1.wav.txt    file2.wav.txt    file3.wav.txt

 

[nobody]

Maybe there has some empty space, etc. in file2.wav file?

 

[angelvg]

File ile2.wav not found.

I think that it should be file2.wav

The file exist


$ ls *.wav


file1.wav    file2.wav    file3.wav

The name in the file list.txt is OK


$ cat list.txt


file1.wav
file2.wav
file3.wav

 

[angelvg]

Maybe there has some empty space, etc. in file2.wav file?

Can you please test it yourself? I've already tried it on two different versions of FreeBSD with the different result...

14.0-RELEASE-p9

File e2.wav not found

14.2-RELEASE-p4

File ile2.wav not found

Different e2.wav vs ile2.wav

 

[covacat]

hexdump -Cv list.txt

 

[angelvg]

hexdump -Cv list.txt

00000000  66 69 6c 65 31 2e 77 61  76 0a 66 69 6c 65 32 2e  |file1.wav.file2.|
00000010  77 61 76 0a 66 69 6c 65  33 2e 77 61 76 0a        |wav.file3.wav.|

 

[covacat]

unset IFS

 

[angelvg]

unset IFS

How do I use it?

 

[covacat]

put that at the top of the script

 

[angelvg]

put that at the top of the script

The new code

#!/bin/sh

unset IFS

WORKDIR='/tmp/test'

cd "${WORKDIR}" || exit 1

# Bucle
while read -r FILENAME; do
...

When running

Transcoding file1.wav. . .
...
File ile2.wav not found
Transcoding file3.wav. . .

The result

file1.wav.ogg    file3.wav.ogg

 

[covacat]

ok
put < /dev/null at yhe end of ffmpeg line

 

[angelvg]

ok
put < /dev/null at yhe end of ffmpeg line

Eureka!

You are the best...

The line in the script is:

ffmpeg -y -hide_banner -i "${FILENAME}" -c:a libvorbis -ar 44100 "${FILENAME}".ogg < /dev/null

Thank you!

 

[kent_dorfman766]

ok
put < /dev/null at yhe end of ffmpeg line

I think it is important to explain why this fixes the problem. On casual inspection it doesn't seem necessary but is obviously a fix, so why?

 

[covacat]

seems like ffmpeg will read something from stdin if it cans and will fsck things up (the next shell read)
maybe someone can search the docs for why it does it....

 

[kent_dorfman766]

seems like ffmpeg will read something from stdin if it cans and will fsck things up (the next shell read)
maybe someone can search the docs for why it does it....

not surprised, but thanks for the additional input. ffmpeg can be quite infuriating. I use it for a lot of batch mode transcoding which is why my "higher than normal" interest.