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• FFmpeg : Keep image quality during moving the video screen along image

  15 janvier 2020, par ArmKh

  I have a FFmpeg command which is moving the video screen along image. From the TOP LEFT position to BOTTOM RIGHT

  Here is the ffmpeg command

  ffmpeg -y -loop 1 -t 5 -i 1.jpg -loop 1 -t 5 -i 2.jpg -loop 1 -t 5 -i 3.jpg -i song.mp3 
  
  -filter_complex "
  
  [0:v]crop=1280:1280:((iw-ow)*t)/5:((ih-oh)*t)/5[v0];
  
  [1:v]crop=1280:1280:((iw-ow)*t)/5:((ih-oh)*t)/5[v1];
  
  [2:v]crop=1280:1280:((iw-ow)*t)/5:((ih-oh)*t)/5[v2];
  
  [v0][v1][v2]concat=n=3:v=1:a=0,fps=25,format=yuv420p[v]" -map "[v]" -map 3:a -shortest top_left_to_bottom_right.mp4

  I’m using images with 3000x3000 sizes and the video screen sizes are 1280x1280. So, the command works great but in the video, I don’t have the same images quality

  For example : Initial image

  

  Image part in the video

  

  The image in the video looks like zoomed ( scaled ) as well ?
  So, is there any way to keep the image quality and maybe a ratio as well ?

• find the timestamp of a sound sample of an mp3 with linux or python

  23 juin 2020, par cardamom

  I am slowly working on a project which where it would be very useful if the computer could find where in an mp3 file a certain sample occurs. I would restrict this problem to meaning a fairly exact snippet of the audio, not just for example the chorus in a song on a different recording by the same band where it would become more some kind of machine learning problem. Am thinking if it has no noise added and comes from the same file, it should somehow be possible to locate the time at which it occurs without machine learning, just like grep can find the lines in a textfile where a word occurs.

  


  In case you don't have an mp3 lying around, can set up the problem with some music available on the net which is in the public domain, so nobody complains :

  


  curl https://web.archive.org/web/20041019004300/http://www.navyband.navy.mil/anthems/ANTHEMS/United%20Kingdom.mp3 --output godsavethequeen.mp3


  


  It's a minute long :

  


  exiftool godsavethequeen.mp3 | grep Duration
Duration                        : 0:01:03 (approx)


  


  Now cut out a bit between 30 and 33 seconds (the bit which goes la la la la..) :

  


  ffmpeg -ss 30 -to 33 -i godsavethequeen.mp3 gstq_sample.mp3


  


  both files in the folder :

  


  $ ls -la
-rw-r--r-- 1 cardamom cardamom   48736 Jun 23 00:08 gstq_sample.mp3
-rw-r--r-- 1 cardamom cardamom 1007055 Jun 22 23:57 godsavethequeen.mp3


  


  This is what am after :

  


  $ findsoundsample gstq_sample.mp3 godsavethequeen.mp3
start 30 end 33


  


  Am happy if it is a bash script or a python solution, even using some kind of python library. Sometimes if you use the wrong tool, the solution might work but look horrible, so whichever tool is more suitable. This is a one minute mp3, have not thought yet about performance just about getting it done at all, but would like some scalability, eg find ten seconds somewhere in half an hour.

  


• Using ffmpeg to get a passthrough stream and create an audio resource for discordjs/voice ?

  5 novembre 2022, par Zer0

  I have access to an hls manifest file which i can use to download a song.
I use the following command to download it/pipe it to stdout :
ffmpeg -i 'https://api.someurl.com/1/2/3/stream.ismd/manifest.m3u8' -vn -sn -f flv -c copy -|ffmpeg -i - -b:a 192k -f mp3 -.

  


  I am successfully able to output a playable mp3 from this command.

  


  I am looking for a way to get the same kind of result in nodejs and get a readable stream from the final download and then pipe it to createAudioResource() to make it playable in a discord voice channel.

  


  There is a nodejs module called m3u8stream which i tried using with the code mentioned below but i couldnt get it to work as my knowledge of nodejs streams is limited and the documentation is confusing to understand.

  


  const stream = new PassThrough()
let resource
const stream = m3u8stream('https://api.someurl.com/1/2/3/stream.ismd/manifest.m3u8', {parser : 'm3u8',
requestOptions : {headers : {"content-type" : "video/mp4"}}
}).pipe(stream)
stream.on('data', d=>{resource = createAudioResource(d)})
player.play(resource)


  


  This code did not work and i am assuming this has something to do with m3u8stream itself because piping the stream to fs.createWriteStream('file.mp4') as shown in their example results in a zero kb mp4 file.

  


  I am sure there is be a better tool or a way to get a stream from the manifest and get it to play on discord and i would be happy to know about them as i am not bound to use ffmpeg for this.
Any help to make this work is appreciated. Thanks !