extract


Extract audio from online video

Using the youtube-dl command line application you can download videos and directly extract the audio of the video in various formats.

youtube-dl supports a large variety of online video hosts, including:

  • youtube.com
  • 9gag.com
  • crunchyroll.com
  • dailymotion.com
  • southparkstudios.com

Note: Please be sure that you are allowed to download a video before you do that, many of these hosts do not expect that you will be downloading their videos as they do not allow that.

The following command, will download a video, convert it to an mp3 and delete the original video:

youtube-dl --extract-audio --audio-format mp3 https://www.youtube.com/watch?v=cwI-n3sI8ec

If you want to keep the original video, you just add the parameter -k or --keep-video.

The --audio-format parameter accepts other types of audio format outputs, specifically it supports

youtube-dl is a very powerful tool, advice the documentation for some of the great features it supports.

 


Using .tgz files 1

Create

To create a .tgz file, we used tar with the following parameters -czf:

  • -c or --create will create a new archive.
  • -z– or --gzip or --gunzip or --ungzip will filter the archive through gzip and compress it.
  • -f or --file=ARCHIVE will use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable TAPE. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default.

Example:

tar -czf $ARCHIVE_FILE_NAME.tgz $PATH_TO_COMPRESS;

Please note that the order of the parameters will not change the result.

Extract

To extract a .tgz or .tar.gz file using tar we used the following parameters -xzf:

  • -x or --extract --get will extract the files from the archive. Arguments are optional. When given, they specify names of the archive members to be extracted.
  • -z– or --gzip or --gunzip or --ungzip will filter the archive through gzip and decompress it.
  • -f or --file=ARCHIVE will use archive file or device ARCHIVE. If this option is not given, tar will first examine the environment variable TAPE. If it is set, its value will be used as the archive name. Otherwise, tar will assume the compiled-in default.

Example:

tar -xzf $ARCHIVE_FILE_NAME.tgz;


ffmpeg: Extract audio from .MKV to .MP3 6

The following command will find all mkv files that are in the current directory and in all sub-folders and extract the audio to mp3 format.

find . -type f -name "*.mkv" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -c:a libmp3lame -y "${FILE%.mkv}.mp3";' _ '{}' \;

The filename of the audio file will be the same as the mkv video with the correct extension. The mkv extension will be removed and replaced by the mp3 extension e.g hi.mkv will create a new file named hi.mp3


ffmpeg: Extract audio from .MP4 to .MP3

The following command will find all mp4 files that are in the current directory and in all sub-folders and extract the audio to mp3 format.

find . -type f -iname "*.mp4" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -y "${FILE%.mp4}.mp3";' _ '{}' \;

The filename of the audio file will be the same as the mp4 video with the correct extension. The mp4 extension will be removed and replaced by the mp3 extension e.g hi.mp4 will become hi.mp3


ffmpeg: Extract audio from .WEBM to .OGG 3

If you need to extract the audio from an .WEBM movie file to an .OGG audio file you can  execute the following:

FILE="the-file-you-want-to-process.webm";
ffmpeg -i "${FILE}" -vn -y "${FILE%.webm}.ogg"

The first command will assign the file name to a variable, we do this to avoid typing errors in the second command where we might want to use the same name for the audio file.

The second command, will use ffmpeg to extract the audio. The -i flag, indicates the file name of the input. We used the flag -vn that will instruct ffmpeg to disable video recording. The -acodec flag will set the output audio codec to vorbis. The -y flag will overwrite output file without asking, so be careful when you use it.

In case we want to automatically process (batch process) all .WEBM video files in a folder we can use the following:

for FILE in *.webm;
do
    echo -e "Processing video '\e[32m$FILE\e[0m'";
    ffmpeg -i "${FILE}" -vn -y "${FILE%.webm}.ogg"
done

The above script will find all .WEBM files in the folder and process them one after the other.

 

UPDATE:

The following command will find all webm files that are in the current directory and in all sub-folders and extract the audio to ogg format.

find . -type f -iname "*.webm" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -y "${FILE%.webm}.ogg";' _ '{}' \;

The filename of the audio file will be the same as the webm video with the correct extension. The webm extension will be removed and replaced by the ogg extension e.g hi.webm will become hi.ogg

 


ffmpeg: Extract audio from .WEBM to .AAC 2

If you need to extract the audio from an .WEBM movie file to an .AAC audio file you can  execute the following:

FILE="the-file-you-want-to-process.webm";
ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -strict -2 -y "${FILE%.webm}.aac";

The first command will assign the file name to a variable, we do this to avoid typing errors in the second command where we might want to use the same name for the audio file.

The second command, will use ffmpeg to extract the audio. The -i flag, indicates the file name of the input. We used the flag -vn that will instruct ffmpeg to disable video recording. The -ab flag will set the bit rate to 128k. The -ar flag will set the audio sample rate to 441000 Hz.  The flags -strict -2 are required as the native FFmpeg AAC encoder that is included with ffmpeg is considered an experimental encoder. The -y flag will overwrite output file without asking, so be careful when you use it.

In case we want to automatically process (batch process) all .WEBM video files in a folder we can use the following:

for FILE in *.webm; do
    echo -e "Processing video '\e[32m$FILE\e[0m'";
    ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -strict -2 -y "${FILE%.webm}.aac";
done;

The above script will find all .WEBM files in the folder and process them one after the other.

 

UPDATE:

The following command will find all webm files that are in the current directory and in all sub-folders and extract the audio to aac format.

find . -type f -iname "*.webm" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -strict -2 -y "${FILE%.webm}.aac";' _ '{}' \;

The filename of the audio file will be the same as the webm video with the correct extension. The webm extension will be removed and replaced by the aac extension e.g hi.webm will become hi.aac

 


ffmpeg: Extract audio from .WEBM to .MP3 6

If you need to extract the audio from an .WEBM movie file to an .MP3 audio file you can  execute the following:

FILE="the-file-you-want-to-process.webm";
ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -y "${FILE%.webm}.mp3";

The first command will assign the file name to a variable, we do this to avoid typing errors in the second command where we might want to use the same name for the audio file.

The second command, will use ffmpeg to extract the audio. The -i flag, indicates the file name of the input. We used the flag -vn that will instruct ffmpeg to disable video recording. The -ab flag will set the bit rate to 128k. The -ar flag will set the audio sample rate to 441000 Hz.  The -y flag will overwrite output file without asking, so be careful when you use it.

In case we want to automatically process (batch process) all .WEBM video files in a folder we can use the following:

for FILE in *.webm; do
    echo -e "Processing video '\e[32m$FILE\e[0m'";
    ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -y "${FILE%.webm}.mp3";
done;

The above script will find all .WEBM files in the folder and process them one after the other.

 

UPDATE:

The following command will find all webm files that are in the current directory and in all sub-folders and extract the audio to mp3 format.

find . -type f -iname "*.webm" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -y "${FILE%.webm}.mp3";' _ '{}' \;

The filename of the audio file will be the same as the webm video with the correct extension. The webm extension will be removed and replaced by the mp3 extension e.g hi.webm will become hi.mp3

 


ffmpeg: Extract audio from .MP4 to .OGG 1

If you need to extract the audio from an .MP4 movie file to an .OGG audio file you can  execute the following:

FILE="the-file-you-want-to-process.mp4";
ffmpeg -i "${FILE}" -vn -acodec libvorbis -y "${FILE%.mp4}.ogg"

The first command will assign the file name to a variable, we do this to avoid typing errors in the second command where we might want to use the same name for the audio file.

The second command, will use ffmpeg to extract the audio. The -i flag, indicates the file name of the input. We used the flag -vn that will instruct ffmpeg to disable video recording. The -acodec flag will set the output audio codec to vorbis. The -y flag will overwrite output file without asking, so be careful when you use it.

In case we want to automatically process (batch process) all .MP4 video files in a folder we can use the following:

for FILE in *.mp4;
do
    echo -e "Processing video '\e[32m$FILE\e[0m'";
    ffmpeg -i "${FILE}" -vn -acodec libvorbis -y "${FILE%.mp4}.ogg";
done

The above script will find all .MP4 files in the folder and process them one after the other.

 

UPDATE:

The following command will find all mp4 files that are in the current directory and in all sub-folders and extract the audio to ogg format.

find . -type f -iname "*.mp4" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -vn -acodec libvorbis -y "${FILE%.mp4}.ogg";' _ '{}' \;

The filename of the audio file will be the same as the mp4 video with the correct extension. The mp4 extension will be removed and replaced by the ogg extension e.g hi.mp4 will become hi.ogg

 


Bash: grep: A couple of usefull applications

(How) to delete all empty lines from a file:

cat someFile | grep -v '^$'

(How) to get all numbers that have no sign in front of them (all positive numbers, from a file where on each line there is one number only):

cat someFile | grep ^[0-9]

(How) to extract all negative numbers (from a file where on each line there is one number only):
You can of course replace the minus ‘-‘ character with any other you want to use as a starting character for a line.

cat someFile | grep ^-