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• How can I add chapters to .mp4 files using a python script ? [duplicate]

  7 mars 2023, par Random

  Is there an easy way to add chapters (i.e. : sections with titles) to .mp4 files using a python script ?

  


  For example, the script could process a 3-minutes video and label the first minute as "Beginning", the second minute as "Middle", and the last minute as "End".

  


  The only solution (link) I stumbled upon so far involves using a ffmpeg command on the command line to extract the original ffmetadata from the video file before appending the chapters to it and updating the video with it.

  


  However, I would like the process to be automated using a python script (instead of having to use the command line each time I have to process a video).

  


• how to read partial fragmented mp4 from buffer or stdin

  1er mars 2023, par poush

  I am facing a weird challenge. I am still wondering if there's something wrong in my understanding of fragmented mp4 concepts.

  


  I have a buffer stream of a video file, that I am streaming from AWS. Subsequently I am passing it to stdin and using ffmpeg to encode it.

  


  What I want to achieve is if I skip 10000 initial bytes (say) from the source (which is S3 here), I still want to be able to encode the rest of the video in the buffer.

  


  I tried to create a fragmented mp4 (10s) and split the file into chunks of 20MB and now if I try to play any of the chunks except the first one, it doesn't work. I am trying to understand how HLS or Dash uses fragments to jump directly to a part of the video.

  


  I want to mimic basically the HLS player behaviour. Say, if I want to start streaming from S3 bucket from 200000 bytes, then I want to be able encode the video from there.

  


• ffmpeg messes up variables [duplicate]

  14 février 2023, par poeplva19

  I am trying to split audio files by their chapters. I have downloaded this as audio with yt-dlp with its chapters on. I have tried this very simple script to do the job :

  


  #!/bin/sh

ffmpeg -loglevel 0 -i "$1" -f ffmetadata meta # take the metadata and output it to the file meta
cat meta | grep "END" | awk -F"=" '{print $2}' | awk -F"007000000" '{print $1}' > ends # 
cat meta | grep "title=" | awk -F"=" '{print $2}' | cut -c4- > titles
from="0"
count=1
while IFS= read -r to; do
    title=$(head -$count titles | tail -1)  
    ffmpeg -loglevel 0 -i "$1" -ss $from -to $to -c copy "$title".webm
    echo $from $to
    count=$(( $count+1 ))
    from=$to
done < ends


  


  You see that I echo out $from and $to because I noticed they are just wrong. Why is this ? When I comment out the ffmpeg command in the while loop, the variables $from and $to turn out to be correct, but when it is uncommented they just become some stupid numbers.
Commented output :

  


  0 465
465 770
770 890
890 1208
1208 1554
1554 1793
1793 2249
2249 2681
2681 2952
2952 3493
3493 3797
3797 3998
3998 4246
4246 4585
4585 5235
5235 5375
5375 5796
5796 6368
6368 6696
6696 6961


  


  Uncommented output :

  


  0 465
465 70
70 890
890 08
08 1554
1554 3
3 2249
2249
2952
2952 3493
3493
3998
3998 4246
4246 5235
5235 796
796 6368
6368


  


  I tried lots of other stuff thinking that they might be the problem but they didn't change anything. One I remember is I tried havin $from and $to in the form of %H:%M:%S which, again, gave the same result.
Thanks in advance.