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• How to get the real, actual duration of an MP3 file (VBR or CBR) server-side

  27 janvier 2021, par SquareCat

  I used to calculate the duration of MP3 files server-side using ffmpeg - which seemed to work fine. Today i discovered that some of the calculations were wrong. Somehow, for some reason, ffmpeg will miscalculate the duration and it seems to happen with variable bit rate mp3 files only.

  



  When testing this locally, i noticed that ffmpeg printed two extra lines in green.

  



  Command used :

  



  ffmpeg -i song_9747c077aef8.mp3


  



  ffmpeg says :

  



  [mp3 @ 0x102052600] max_analyze_duration 5000000 reached at 5015510
[mp3 @ 0x102052600] Estimating duration from bitrate, this may be inaccurate


  



  After a nice, warm google session, i discovered some posts on this, but no solution was found.

  



  I then tried to increase the maximum duration :

  



  ffmpeg -analyzeduration 999999999 -i song_9747c077aef8.mp3


  



  After this, ffmpeg returned only the second line :

  



  [mp3 @ 0x102052600] Estimating duration from bitrate, this may be inaccurate


  



  But in either case, the calculated duration was just plain wrong. Comparing it to VLC i noticed that there the duration is correct.

  



  After more research i stumbled over mp3info - which i installed and used.

  



  mp3info -p "%S" song_9747c077aef8.mp3


  



  mp3info then returned the CORRECT duration, but only as an integer, which i cannot use as i need a more accurate number here. The reason for this was explained in a comment below, by user blahdiblah - mp3info is simply pulling ID3 info from the file and not actually performing any calculations.

  



  I also tried using mplayer to retrieve the duration, but just as ffmpeg, mplayer is returning the wrong value.

  


• FFMPEG UDP MPEG2TS to Cable TV Channel - Video & Audio Problems

  30 janvier 2019, par user2884023

  Channel Feed Distored Picture

  $ ffmpeg
  
  -re
  
  -i playlist1.txt
  
  -b:v 15000k 
  
  -bufsize 15000k
  
  -maxrate 16000k
  
  -f mpegts "udp://XXX.XXX.X.XXX:XXXX"

  I have mpeg2.ts files encoded to CBR15mbs.
  The files are set to different frame rates. Although initial testing was just playing 1 file.
  They are currently 1080p I think without declaring the frame rate, they are defaulting to 30fps.
  From the server locally via Port2 (that we are using to send our feed), everything plays fine via FFPLAY.
  The final out put local CATV is pixelated and distorted, the video is missing data playing slowly and the audio is choppy / distorted.
  I even tried just a 192kps .mp2 and it played distorted on the CATV channel.
  They set me up with a cable modem. 2 ports, 1 WAN, 1 a dedicated port to feed their head end and I have a fiber synchronous 20/20 connection.

  I am guessing its a packet issue, perhaps on our end with our FFMPEG setup ? And maybe FFPLAY isn’t as sensitive to the actual distro process.

  Perhaps the secret lies here, but there isn’t much info about them, even scouring the net.

  ?pkt_size=188&buffer_size=65535

  For example what is this one :

  broadcast=1|0

  Explicitly allow or disallow UDP broadcasting.

  I apologize if data is missing, please ask questions. I didn’t want to write a novel.

  I am hoping some can provide the correct code so my signal is corrected. I assume the problem is on our end, and not the CATV end. At least I can try some solutions on our end first. I can make real-time FFMPEG changes to the server, and see the channel results instantly so that helps.

  Finally, the fact it wouldn’t even play a .mp2 audio file cleanly on the channel, does make me wonder, is there a problem on their end, or is it a config on our end, and we just need the correct answer ?

• How to fix "FFmpeg command cannot exec when multiple mp3 file to process into one" on server side

  7 février 2019, par Harshil Dholakiya

  I am using FFmpeg in my php yii2 project. FFmpeg working fine in my project but one major problem is execute FFmpeg command with multiple input file. When i try to use single file to process in ffmpeg command then it works. so, how can i fix this problem ? I am using hostGator shared plan for my project. Please, help if is there any process limit or file open limit on server that i don’t know.

  I have tried using this command in php exec() :

  ffmpeg -y -i /uploads/ac/10122018-09351115-a94rlvlawvikskb4vdrca.mp3 -i /uploads/ac/09012019-035928988-assknyrk8oujccwevir7.mp3 -f lavfi -i anullsrc -filter_complex "[2]atrim=duration=3[g0];[2]atrim=duration=1[g1];[2]atrim=duration=5[g2];[g0][0][g1][1][g2]concat=n=5:v=0:a=1" /uploads/jm/concat.mp3 2>&1

  Above command works local side but not working on server side.

  output on server side with error code 1:
  
  Press [q] to stop, [?] for help
  
  pthread_create failed: Resource temporarily unavailable. Try to increase `ulimit -v` or decrease `ulimit -s`.
  
  Conversion failed!