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• ffmpeg parse error with bass audio filter and expression evaluation

  23 août 2018, par Shaun

  I am trying to dynamically change the bass of an audio file as a function of time. For instance, say I would like to gradually increase the bass over a period of 5 seconds. The command I am using is

  ffmpeg -y -i in.wav -af \
      "bass=g='if(lte(t,5),-20+(20/5)*t,0)':width_type=q:w=0.70" \
      out.wav
  

  However I am receiving the error

  [bass @ 0x19890c0] [Eval @ 0x7ffd8e143630] Unknown function in 't,5),-20+(20/5)*t,0)'
  

  As a second attempt, I instead tried to use min instead of lte, the command being

  ffmpeg -y -i in.wav -af \
      "bass=g='min(-20+20*t/5,0)':width_type=q:w=0.70" \
       out.wav
  

  but got a slightly different error

  [bass @ 0x263d040] [Eval @ 0x7fff0c8e7dc0] Invalid chars '(-20+20*t/5,0)' at the end of expression 'min(-20+20*t/5,0)'
  

• Changing Audio Volume using FFmpeg Android

  23 août 2018, par kataroty

  As I have understood, the only way to change FFmpeg volume is to do it throught a command line.

  This is what should change the volume of the audio :

  ffmpeg -i input.wav -filter:a "volume=1.5" output.wav
  

  Now I have used FFmpeg with command line before and it looked like this and gave me no errors:

      String[] cmd = { "-i" , pcmtowavTempFile.toString(), "-i", mp3towavTempFile.toString(), "-filter_complex", "amix=inputs=2:duration=first:dropout_transition=3", combinedwavTempFile.toString()};
      ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
          @Override
          public void onSuccess(String message) {                
              super.onSuccess(message);
              encodeWavToAAC();
          }
          @Override
          public void onFailure(String message) {
              super.onFailure(message);
              onError(message);
          }
      });
  

  But If I try to do it with audio volume in the same method, it just ignores it :

      String[] cmd = { "-i" , pcmtowavTempFile.toString(),  "-filter:a", "volume=1.3", pcmtowavTempFile.toString()};
      ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
          @Override
          public void onSuccess(String message) {
              super.onSuccess(message);
          }
          @Override
          public void onFailure(String message) {
              super.onFailure(message);
  
          }
      });
  

  I get neither, no success or error message with the last volume change method.

  Since the volume is there between " ", I tried adding this :

  String[] cmd = { "-i" , pcmtowavTempFile.toString(),  "-filter:a", "\"volume=1.3\"", pcmtowavTempFile.toString()};
  

  But the app started crashing after adding this line.

• FFMPEG download m3u8 faster

  23 août 2018, par Bruno Andrade

  I have a server with 1 Gbps port speed where I am trying to download m3u8 videos from a website. But he is very slow. I want to know if there is something in my ffmpeg code that I can do to make it get faster?

  ffmpeg -hide_banner -loglevel verbose -n -i http://example.com/list.m3u8 -map 0:4 -map 0:5 -acodec copy -bsf:a aac_adtstoasc -vcodec copy video.mp4 1> log.tx  2>&1
  

  Does the CPU influence this type of ffmpeg download? What I understand of the code is that it is saying not to encode anything. Download the same video is on the site. So CPU processing would not influence the speed correct?

• FFMPEG outputs stream to UDP port, but no packets received on that port

  23 août 2018, par user10260735

  I am a bit new to FFMPEG and will appreciate any help I can get! Basically, I am trying to transcode a 'webm' UDP stream to Opus audio stream, and then finally output that to a specific UDP port on my network.

  This is the command I am using:

  ffmpeg -re -i udp://127.0.0.1:2222 -vn -map 0:a -c:a libopus -f ogg udp://127.0.0.1:2224
  

  However, when I check on port 2224, I do not receive any packets.

  FFMPEG is definitely receiving the input packets because if I run the following command, the file plays out perfectly:

  ffmpeg -re -i udp://127.0.0.1:2222 -vn -map 0:a -c:a libopus -f test.opus
  

  Does anyone have any suggestions on what mistake I am making?

• fluent-ffmpeg video merge with hardware acceleration using NVIDIA graphics card

  23 août 2018, par krisalay

  I am trying to concatenate videos to one single .mp4 file.

  If I am not using hardware acceleration then the merge is working fine.

  However, when I provide -hwaccel cuvid as inputOptions and -c:v h264_nvenc as outputOptions then it throws error:

  ffmpeg exited with code 1: Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  The code:

  ffmpeg
  .input('video1.mp4')
  .input('video2.mp4')
  .inputOptions(['-loglevel error','-hwaccel cuvid'])
  .outputOptions('-c:v h264_nvenc')
  .mergeToFile('filepath.mp4')
  

  What could be the possible reason for the error? And what can be the solution to resolve the error?