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• Streaming a video using ffmpeg from images during the images generation is still on-going

  1er août 2019, par 박성우

  I’m trying to stream a video to web using ffmpeg. My code creates some random images in same shape and i wanted to stream on web. The problem is that image generation is still on-going when I start to stream the video.

  I found that mp4 format is not a suitable one for streaming and gonna changed it to flv or webm.
  So, that i tried is as bellow.

  ffmpeg -i PATH_TO_IMAGES/%5d.jpg -i MY_AUDIO.WAV output.flv
  
  ffmpeg -i PATH_TO_IMAGES/%5d.jpg -i MY_AUDIO.WAV output.webm

  but my problem comes from,
  first, i could not load images generated after above command is executed.
  second, when i used webm, i should reload the video to get next segment.

  first one is critical. Could anyone advise if there is any way to load images during encoding or other way to go ?

  Thank you.

• FFmpeg downloading entire live stream when making a small clip

  6 février 2021, par stevendesu

  Setup

  


  I'm using FFmpeg to generate video clips from M3U8 videos. The command looks like this :

  


  ffmpeg -ss <start> -i &lt;1080p-chunklist-url> -c:v copy -c:a copy -t <duration> -f mp4 -y out.mp4&#xA;</duration></start>

  


  For example, to create a 30-second clip starting at the 5-minute mark for a particular video, the command would be :

  


  ffmpeg -ss 300 -i https://example.com/path/to/1080p/index.m3u8 -c:v copy -c:a copy -t 30 -f mp4 -y out.mp4


  


  Some caveats I'm already aware of :

  


  

  • If -ss comes after -i then FFmpeg will attempt to download the entire M3U8 instead of just the relevant TS files, and will parse the entire video contents looking for the exact timestamp. By putting -ss before -i FFmpeg uses "seek points", which with HLS videos means it looks at the M3U8 and only downloads relevant TS files

  


  • TS file boundaries function as "seek points" in HLS, so if a TS file starts at 4:51 and the next TS file starts at 5:01, this command will start the clip at 4:51 instead of 5:01 (it prefers the first seek point before the requested time)

  


  • The -t parameter sets an exact clip duration instead of an ending position, so in the above example of a clip starting at 4:51 the same clip would end at 5:21 instead of 5:30

  


  


  In theory I can utilize -to instead of -t to specify an ending time of 5:30, however in practice this hasn't worked. Also in theory I can force -accurate_seeking to discard the contents from 4:51 to 5:00 and start the clip where I wanted it, but I learned this only works for transcodes and not transmux

  


  Now to the meat of my problem :

  


  Problem

  


  When the M3U8 URL provided is a live stream (no #EXT-X-ENDLIST tag) then FFmpeg does not behave correctly. On FFmpeg versions 4.2.1 and earlier, it starts by downloading the TS file containing my clip segment, then proceeds to download every TS file in the M3U8 then hangs while waiting for new TS files to become available, downloading them as they appear - even hours after the end of the section I wanted to clip. On FFmpeg version 4.2.2 and later, I can create clips so long as they end before the second-to-last TS file. If the live stream currently has 20 minutes of video data and I create a clip from 19:30 - 19:40 (ending right at the start of the second-to-last TS file, assuming a 10-second TS file duration) then it will behave the same as 4.2.1 : waiting infinitely to download the entire video.

  


  The "2 TS files from the end" rule I believe is related to FFmpeg's initial probe of the video to get stream data. In the aforementioned 20-minute long video, if I make a clip from 3:00 to 3:30 (well before the end of the stream) it will first download TS files 119 and 120 (19:40-19:50 and 19:50-20:00), then it displays a list of the streams in the video (audio, video, metadata), then it downloads TS files 19 - 21 (containing the actual data I want for my clip)

  


  Is there a way to fix it so I can properly make clips of sections near the "end" of live M3U8s ?

  


• Java - handing file deletion

  2 janvier 2016, par QQMusic

  So I am using the youtube-dl command line program within Java with simple command line execute function and coupling it with ffmpeg to convert to mp3. Now the thing I am having trouble with it the fact that after I get the .mp4 file from youtube-dl, when I convert it into a .mp3, it will create a completely separate file.

  So the way it is now :

  1. Get `.mp4`
  
  2. Get `.mp3`
  
  3. delete `.mp4'

  The issue I am facing now is that if the user was to stop the program while it was between step 1 and step 2, then they would be left with the .mp4 file which is not wanted. So is there a way to delete certain files once the user exits the process, whether it being from safely ending the program (this one should be easy), ending the process, or closing the computer ?