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• What is the best way to split videos into equally sized parts using ffmpeg ? [closed]

  18 juin 2024, par GBPU

  I have tried to split an mp4 file into smaller parts of equal time length like this ffmpeg -i ../data/2024-06-02_12-34-51.mp4 -c copy -map 0 -segment_time 00:00:05 -f segment v1_%03d.mp4. However, this produced videos of highly variables size, some 25x larger than others. I assume this was due to inconsistent framerate during recording.

  


  Next, I tried a script that would split based and limit each part to a specific size :

  


  #!/bin/sh
# 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="../data/$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. -f -2)

# Duration that has been encoded so far
CURDURATION=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
while [[ $(bc <<< "$CURDURATION < $DURATION") -eq 1 ]]; do
    # Encode next part
    echo ffmpeg -i "$FILE" -ss "$CURDURATION" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"
    ffmpeg -ss "$CURDURATION" -i "$FILE" -fs "$SIZELIMIT" $FFMPEG_ARGS "$NEXTFILENAME"

    # Duration of the new part
    NEWDURATION=$(ffprobe -i "$NEXTFILENAME" -show_entries format=duration -v quiet -of default=noprint_wrappers=1:nokey=1|cut -d. -f -2)

    # Total duration encoded so far
    echo $CURDURATION
    CURDURATION=$(bc <<< "$CURDURATION + $NEWDURATION")
    echo $CURDURATION

    i=$((i + 1))

    echo "Duration of $NEXTFILENAME: $NEWDURATION"
    echo "Part No. $i starts at $CURDURATION"
    echo "Current Duration: $CURDURATION"

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


  


  I call the script like this : bash split-video.sh 2024-06-02_12-34-51.mp4 10000000 "-c copy"
Unfortunately, this has an issue where some of the sub videos are extremely short and have wildly inconsistent numbers of frames in them (some with nearly 400, others with 1), despite being similar sizes. I am guessing this has something to do with inconsistent framerate and keyframes or something ?

  


  I am curious what the best way to split a video into equally sized parts, and ideally with similar numbers of frames, is using ffmpeg.

  


• avcodec/nvenc : rework on DTS generation

  17 juillet 2024, par Zhao Zhili

  avcodec/nvenc : rework on DTS generation
  Before the patch, the method to generate DTS only works with
  
  timebase equal to 1/fps. With timebase like 1/1000
  ./ffmpeg -i foo.mp4 -an -c:v h264_nvenc -enc_time_base 1/1000 bar.mp4
  pts 0    dts -3
  
  pts 160  dts 37
  
  pts 80   dts 77
  
  pts 40   dts 117 <— invalid
  
  pts 120  dts 157
  
  pts 320  dts 197
  
  pts 240  dts 237
  
  pts 200  dts 277 <— invalid
  
  pts 280  dts 317 <— invalid
  The generated DTS can be larger than PTS, since it only reorder the
  
  input PTS and minus the number of frame delay, which doesn't take
  
  timebase into account. It should minus the "time" of frame delay.
  9a245bd trying to fix the issue, but the implementation is incomplete,
  
  which only use time_base.num. Then it got reverted by ac7c265b33b.
  After this patch :
  pts 0    dts -120
  
  pts 160  dts -80
  
  pts 80   dts -40
  
  pts 40   dts 0
  
  pts 120  dts 40
  
  pts 320  dts 80
  
  pts 240  dts 120
  
  pts 200  dts 160
  
  pts 280  dts 200
  Signed-off-by : Timo Rothenpieler <timo@rothenpieler.org>
  

  • [DH] libavcodec/nvenc.c
  • [DH] libavcodec/nvenc.h

• avformat/mov_chan : add extra checks to channel description count

  17 septembre 2024, par James Almer

  avformat/mov_chan : add extra checks to channel description count
  Make sure it's not zero, and equal or bigger than number of channels
  Fixes : Timeout / DOS
  
  Fixes : 67143/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-4858720481771520
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavformat/mov_chan.c