Using ffmpeg to split video files by size [closed]

Answer 1

I just had the same problem, and after I didn't find a solution here, I wrote a quick bash script for that job.

Features:

• Use ffmpeg's -fs-flag to limit filesize
• Check length of resulting video part and calculate where to start next part
• Enumerate video parts
• proceed with as many parts as needed to contain the whole source file.
• Allow for custom ffmpeg arguments to also reduce resolution and quality in one pass.

It takes only three arguments: The source filename, the desired filesize of each part and the desired arguments for ffmpeg.

Example call to split a file into 64MB parts:

./split-video.sh huge-video.mov 64000000 "-c:v libx264 -crf 23 -c:a copy -vf scale=960:-1"

Finally, the source code of the script:

#!/bin/bash
# Short script to split videos by filesize using ffmpeg by LukeLR

if [ $# -ne 3 ]; then
    echo 'Illegal number of parameters. Needs 3 parameters:'
    echo 'Usage:'
    echo './split-video.sh FILE SIZELIMIT "FFMPEG_ARGS'
    echo 
    echo 'Parameters:'
    echo '    - FILE:        Name of the video file to split'
    echo '    - SIZELIMIT:   Maximum file size of each part (in bytes)'
    echo '    - FFMPEG_ARGS: Additional arguments to pass to each ffmpeg-call'
    echo '                   (video format and quality options etc.)'
    exit 1
fi

FILE="$1"
SIZELIMIT="$2"
FFMPEG_ARGS="$3"

# Duration of the source video
DURATION=$(ffprobe -i "$FILE" -show_entries format=duration -v quiet -of default=noprint_wrappers=1:nokey=1|cut -d. -f1)

# Duration that has been encoded so far
CUR_DURATION=0

# Filename of the source video (without extension)
BASENAME="${FILE%.*}"

# Extension for the video parts
#EXTENSION="${FILE##*.}"
EXTENSION="mp4"

# Number of the current video part
i=1

# Filename of the next video part
NEXTFILENAME="$BASENAME-$i.$EXTENSION"

echo "Duration of source video: $DURATION"

# Until the duration of all partial videos has reached the duration of the source video
while [[ $CUR_DURATION -lt $DURATION ]]; do
    # Encode next part
    echo ffmpeg -i "$FILE" -ss "$CUR_DURATION" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"
    ffmpeg -ss "$CUR_DURATION" -i "$FILE" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"

    # Duration of the new part
    NEW_DURATION=$(ffprobe -i "$NEXTFILENAME" -show_entries format=duration -v quiet -of default=noprint_wrappers=1:nokey=1|cut -d. -f1)

    # Total duration encoded so far
    CUR_DURATION=$((CUR_DURATION + NEW_DURATION))

    i=$((i + 1))

    echo "Duration of $NEXTFILENAME: $NEW_DURATION"
    echo "Part No. $i starts at $CUR_DURATION"

    NEXTFILENAME="$BASENAME-$i.$EXTENSION"
done

Hope, that helps :)

Answer 2

You can do this in one command using mp4box.

mp4box -splits 2000000 filename.mp4

where splits argument takes value in kilobytes. Due to presence of keyframes, segments won't be exactly 2GB.

Answer 3

One idea would be to use ffmpeg with the option -fs. This wil limit the file size. The size of the output file is slightly more than the requested file size.

This will only create one file. But you can build a loop until the whole file is split.

First create a part of the file, then check how long it is with:

ffprobe -i input.file -show_format -v quiet | sed -n 's/duration=//p'

Then start another file with the offset by using -ss

After that do another round of encoding until the whole file is split. You can also use a stream copy for audio and video