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• ffmpeg to split mp4 file into segments... after first segment, audio unsynced

  13 avril 2015, par bcsteeve

  I’ve used the ffmpeg command line shown in this question to split MKV files perfectly for a long time. Now i have some MP4 files that i’d like to split and at first it seemed to work, but every subsequent segment after the first has the audio not synced ! And by several seconds.

  I’ve tried forcing keyframes (advice I found on some other sites) and that didn’t help.

  I tried a different program entirely (Avidemux) and it was able to split the file with proper output, but it was a LOT slower, taking upwards of 3 minutes vs less than 2 seconds with ffmpeg. With Avidemux I was able to determine the exact position of the i-frame where I wanted to split, so thinking perhaps that was the syncing problem I tried that exact position (ie. 00:12:17.111 instead of 00:12:16 or whatever) but that didn’t help either.

  Is there an option I’m missing with ffmpeg to get it to properly sync audio to the video when splitting ?

• How to extract the first frame from a video ?

  10 août 2024, par Andrew

  I am trying to extract the first frame from a video to save it as a preview.

  


  Here's an almost working solution using ffmpeg :

  


  func extractFirstFrame(videoBytes []byte) ([]byte, error) {
    input := bytes.NewReader(videoBytes)

    var output bytes.Buffer

    err := ffmpeg.Input("pipe:0").
        Filter("select", ffmpeg.Args{"gte(n,1)"}).
        Output(
            "pipe:1",
            ffmpeg.KwArgs{
                "vframes": 1,
                "format":  "image2",
                "vcodec":  "mjpeg",
            }).
        WithInput(input).
        WithOutput(&output).
        Run()

    if err != nil {
        return nil, fmt.Errorf("error extracting frame: %v", err)
    }

    return output.Bytes(), nil
}


  


  The problem with this is that it can only process horizontal videos. For some reason it will throw a 0xbebbb1b7 error for a vertical videos. I don't understand why is that, probably because this is my very first time with ffmpeg.

  


  Also, I am concerned if this solution is optimal. My assumption is that the whole video will be loaded into the memory first, which is kinda bad and I would like to avoid that

  


  I use https://github.com/u2takey/ffmpeg-go, but errors are the same even if I run it using exec :

  


      cmd := exec.Command(
        "ffmpeg",
        "-i", "pipe:0",
        "-vf", "select=eq(n\\,0)",
        "-q:v", "3",
        "-f", "image2",
        "pipe:1",
    )


  


  Interestingly enough, I noticed that running command in the terminal will work as expected with any type of video ffmpeg -i .\video_2024-08-10_00-03-00.mp4 -vf "select=eq(n\,0)"  -q:v 3 output_image.jpg, so the problem may be on how I send those videos to my server. I useFiber and send videos as multipart/form-data and then read it like this :

  


      form_data, err := c.FormFile("image")
    file, err := form_data.Open()
    bytes, err := io.ReadAll(file)
    ....
    preview, err := extractFirstFrame(bytes)



  


  I also managed to find logs for the failed attempt :

  


  
ffmpeg version 7.0.2-full_build-www.gyan.dev Copyright (c) 2000-2024 the FFmpeg developers
  built with gcc 13.2.0 (Rev5, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libxevd --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxeve --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-dxva2 --enable-d3d11va --enable-d3d12va --enable-ffnvcodec --enable-libvpl --enable-nvdec --enable-nvenc --enable-vaapi --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      59.  8.100 / 59.  8.100
  libavcodec     61.  3.100 / 61.  3.100
  libavformat    61.  1.100 / 61.  1.100
  libavdevice    61.  1.100 / 61.  1.100
  libavfilter    10.  1.100 / 10.  1.100
  libswscale      8.  1.100 /  8.  1.100
  libswresample   5.  1.100 /  5.  1.100
  libpostproc    58.  1.100 / 58.  1.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a562ff0e80] stream 0, offset 0x30: partial file
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a562ff0e80] Could not find codec parameters for stream 1 (Video: h264 (avc1 / 0x31637661), none, 720x1280, 3093 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'pipe:0':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2024-08-09T20:00:29.000000Z
  Duration: 00:00:06.80, start: 0.000000, bitrate: N/A
  Stream #0:0[0x1](eng): Audio: aac (mp4a / 0x6134706D), 22050 Hz, stereo, fltp, 74 kb/s (default)
      Metadata:
        creation_time   : 2024-08-09T20:00:23.000000Z
        handler_name    : SoundHandle
        vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Video: h264 (avc1 / 0x31637661), none, 720x1280, 3093 kb/s, 30 fps, 30 tbr, 90k tbn (default)
      Metadata:
        creation_time   : 2024-08-09T20:00:23.000000Z
        handler_name    : VideoHandle
        vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:1 -> #0:0 (h264 (native) -> mjpeg (native))
[mov,mp4,m4a,3gp,3g2,mj2 @ 000002a562ff0e80] stream 1, offset 0x5d: partial file
[in#0/mov,mp4,m4a,3gp,3g2,mj2 @ 000002a562fda2c0] Error during demuxing: Invalid data found when processing input
Cannot determine format of input 0:1 after EOF
[vf#0:0 @ 000002a5636c0ec0] Task finished with error code: -1094995529 (Invalid data found when processing input)
[vf#0:0 @ 000002a5636c0ec0] Terminating thread with return code -1094995529 (Invalid data found when processing input)
[vost#0:0/mjpeg @ 000002a5636c0400] Could not open encoder before EOF
[vost#0:0/mjpeg @ 000002a5636c0400] Task finished with error code: -22 (Invalid argument)
[vost#0:0/mjpeg @ 000002a5636c0400] Terminating thread with return code -22 (Invalid argument)
[out#0/image2 @ 000002a562ff5640] Nothing was written into output file, because at least one of its streams received no packets.
frame=    0 fps=0.0 q=0.0 Lsize=       0KiB time=N/A bitrate=N/A speed=N/A
Conversion failed!


  


  Logs for the same video, but ran via terminal :

  


  ffmpeg version 7.0.2-full_build-www.gyan.dev Copyright (c) 2000-2024 the FFmpeg developers
  built with gcc 13.2.0 (Rev5, Built by MSYS2 project)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libaribb24 --enable-libaribcaption --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libxevd --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxeve --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libharfbuzz --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-dxva2 --enable-d3d11va --enable-d3d12va --enable-ffnvcodec --enable-libvpl --enable-nvdec --enable-nvenc --enable-vaapi --enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libcodec2 --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
  libavutil      59.  8.100 / 59.  8.100
  libavcodec     61.  3.100 / 61.  3.100
  libavformat    61.  1.100 / 61.  1.100
  libavdevice    61.  1.100 / 61.  1.100
  libavfilter    10.  1.100 / 10.  1.100
  libswscale      8.  1.100 /  8.  1.100
  libswresample   5.  1.100 /  5.  1.100
  libpostproc    58.  1.100 / 58.  1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\video_2024-08-10_00-03-00.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2024-08-09T20:00:29.000000Z
  Duration: 00:00:06.80, start: 0.000000, bitrate: 3175 kb/s
  Stream #0:0[0x1](eng): Audio: aac (HE-AAC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 74 kb/s (default)
      Metadata:
        creation_time   : 2024-08-09T20:00:23.000000Z
        handler_name    : SoundHandle
        vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 720x1280, 3093 kb/s, 30 fps, 30 tbr, 90k tbn (default)
      Metadata:
        creation_time   : 2024-08-09T20:00:23.000000Z
        handler_name    : VideoHandle
        vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:1 -> #0:0 (h264 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
[swscaler @ 00000219eb4d0c00] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'output_image.jpg':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf61.1.100
  Stream #0:0(eng): Video: mjpeg, yuvj420p(pc, unknown/bt709/bt709, progressive), 720x1280, q=2-31, 200 kb/s, 30 fps, 30 tbn (default)
      Metadata:
        creation_time   : 2024-08-09T20:00:23.000000Z
        handler_name    : VideoHandle
        vendor_id       : [0][0][0][0]
        encoder         : Lavc61.3.100 mjpeg
      Side data:
        cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
[image2 @ 00000219e7aa51c0] The specified filename 'output_image.jpg' does not contain an image sequence pattern or a pattern is invalid.
[image2 @ 00000219e7aa51c0] Use a pattern such as %03d for an image sequence or use the -update option (with -frames:v 1 if needed) to write a single image.
[out#0/image2 @ 00000219e7b5e400] video:49KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
frame=    1 fps=0.0 q=3.0 Lsize=N/A time=00:00:00.03 bitrate=N/A speed=0.322x


  


  I also realized that the problem was not related to the video orientation, but to to the video from a specific source uploaded specifically on my server 🤡 Such a weird coincidence that I decided to test my video upload with those files, but anyway. And those are.... Downloaded instagram reels lol. But again, ffmpeg works just fine when ran in terminal

  


• How to find the loudness of an audio buffer in Node.js ?

  10 mai 2024, par Parshant Khichi

  I have a buffer containing audio data representing a voice recording, and I need to determine its loudness in Node.js. I tried using the fluent-ffmpeg library, as it seemed to offer functionality for audio analysis. However, my attempts to use it to analyze the loudness of the audio buffers were unsuccessful.
Could someone please suggest a reliable approach or provide a code example to help me analyze the loudness of the audio buffers accurately in Node.js ? Any guidance or assistance would be greatly appreciated.