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• Merging video and audio stream, where audio drifts

  22 avril 2015, par TL_IPD

  I want to record audio and video with my raspberry pi b+ 2.
  I tried to accomplish this with one ffmpeg command but this is to slow. and i could not get it working correctly

  I have a raspberry pi camera module and a Cirrus audio card. On the raspberry i have compiled a new kernel with support for the audio card. I also compiled ffmpeg on the raspberr with alsa support

  ~$ ffmpeg
  
  ffmpeg version N-71470-g2db24cf Copyright (c) 2000-2015 the FFmpeg developers
  
  built with gcc 4.6 (Debian 4.6.3-14+rpi1)
  
  configuration: --arch=armel --target-os=linux --enable-gpl --extra-libs=-lasound --enable-nonfree
  
    libavutil      54. 22.101 / 54. 22.101
  
    libavcodec     56. 34.100 / 56. 34.100
  
    libavformat    56. 30.100 / 56. 30.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 14.100 /  5. 14.100
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Hyper fast Audio and Video encoder
  
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

  Now i try to record an audio stream and a video stream ’at the same time’
  I do this my running a shell script

  raspivid -t 60000 -vs -w 1280 -h 720 -b 5000000 -fps 25 -o video.h264 &
  
  arecord -Dhw:sndrpiwsp -r 44100 -c 2 -d 60 -f S32_LE audio.aac

  i also tried with -r 22050 and -f S16_LE

  when running this it sometimes gives an (i think)

  overrun!!! (at least 1038.725 ms long)

  at the end of the script i have two files. a video and a audio file.

  now i want to merge those two together by using ffmpeg

  ffmpeg -i video.h264 -i audio.aac -c:v copy -c:a aac -strict experimental output.mp4

  this gives the output :

  ffmpeg version N-71470-g2db24cf Copyright (c) 2000-2015 the FFmpeg developers
  
  built with gcc 4.6 (Debian 4.6.3-14+rpi1)
  
  configuration: --arch=armel --target-os=linux --enable-gpl --extra-libs=-lasound --enable-nonfree
  
    libavutil      54. 22.101 / 54. 22.101
  
    libavcodec     56. 34.100 / 56. 34.100
  
    libavformat    56. 30.100 / 56. 30.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 14.100 /  5. 14.100
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Input #0, h264, from 'video_1min_3.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p, 1280x720, 25 fps, 25 tbr, 1200k tbn, 50 tbc
  
  Guessed Channel Layout for  Input Stream #1.0 : stereo
  
  Input #1, wav, from 'audio_1min_3.aac':
  
    Duration: 00:01:00.00, bitrate: 705 kb/s
  
      Stream #1:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, 2 channels, s16, 705 kb/s
  
  [mp4 @ 0x3230f20] Codec for stream 0 does not use global headers but container format requires global headers
  
  Output #0, mp4, to 'output_1min_3.mp4':
  
    Metadata:
  
      encoder         : Lavf56.30.100
  
      Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1280x720, q=2-31, 25 fps, 25 tbr, 1200k tbn, 1200k tbc
  
      Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 22050 Hz, stereo, fltp, 128 kb/s
  
      Metadata:
  
        encoder         : Lavc56.34.100 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  frame= 1822 fps=310 q=-1.0 Lsize=   33269kB time=00:01:12.84 bitrate=3741.7kbits/s
  
  video:32300kB audio:941kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.086073%

  so finally i have a file output.mp4 that is a movie with audio that is in sync at the beginning but drifts away to a difference of about 4 seconds. where the audio is ahead of the video.

  I hope you can help me trying to solve this issue so the audio does not drift away anymore.

  Thanks in advance

  ( i tried to be as clear as possible )

• How to merge two audio files and remove their overlap [closed]

  14 septembre 2024, par jackiechan Zebra

  I have two mp3 files, there have some overlap. The last few seconds, normally less than 2 second, of the first file are always appear on the first few seconds of the last file.

  


  How can I conbine the two audio files into one and eliminate the overlap part ?

  


  

  1. Currently, audio files are mp3.

  


  2. Expecting a python lib. I know FFMPEG may work, but I have no experience.

  


  3. Other programming languages solution are also fine.

  


  


  Give me some keywords and I hope I can do the rest.

  


• FFMPEG Imitation decoding artefacts [closed]

  17 juillet 2024, par Тимур Снежок

  I'd like to figure out influence decoding artefacts on my computer vision algorithm so i have to mess up my .mp4 file. Are there methods do this for ?

  


  I hope reach effect like effect dropping frame from stream or efffect corrupted files.

  


  Thanks !