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• Frequency response of ffmpeg filters

  13 novembre 2020, par Dr_Click

  I'm using ffmpeg to decode and encode signal. It works perfectly and I added filters. For example, I'm using such a command :

  


  ffmpeg -re -i /home/dr_click/live.wav -af "anequalizer=c0 f=200 w=100 g=-5 t=0|c1 f=200 w=100 g=-5 t=0, anequalizer=c0 f=1000 w=100 g=3 t=0|c1 f=1000 w=100 g=3 t=0" -acodec pcm_s16be -ar 44100 -ac 2 -f rtp rtp://127.0.0.1:1234


  


  I'm streaming my file, adding 2 filters with 200 Hz and 1000 Hz as central frequency and 100 Hz width and it works.

  


  With such a filter, I know my gain will be -5db at 200Hz. But what is the gain for frequencies at 250 Hz ? Still -5db ? -4.5db ? -3db ? And same question at 350Hz or any other frequency.

  


  What I'm looking for and didn't found is the way to get the frequency response of such a filter for a bandwith from 20Hz to 20kHz. In other words, what I'd like to know for any frequency is : gain = f (frequency) with a given ffmpeg filter

  


  Thank you for your help,

  


  Dr_Click

  


• AWS Lambda failed to resolve hostname in child_process spawn

  14 juin, par warly

  i'm trying to get ffmpeg working in AWS Lambda reading from and writing to S3. I crawled through dozens of aws documentations, stackoverflow questions and blog posts. All do it slightly different, but in the end none of them worked for me. So I hope to find help here :)
I sticked to the tutorial from InPlainEnglish : https://plainenglish.io/community/automated-video-processing-with-aws-lambda-and-ffmpeg-2834b7

  


  The ffprobe command does work, so ffmpeg is callable. But when calling ffmpeg within a child_process.spawn command i get the error Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error

  


  export const handler = async (event) => {
    const s3 = new S3Client({});
    const bucket = event.Records[0].s3.bucket.name;
    const sourceKey = event.Records[0].s3.object.key;
    const sourceURL = await getSignedUrl(s3, new GetObjectCommand({
        Bucket: bucket,
        Key: sourceKey,
    }), {
        expiresIn: 900,
    });

    const tmpFilePath = 'tmp/video.mp4';
    const { convertOut } = await commander(`/opt/ffmpeg -i "${sourceURL}" -vf scale=1080:-2,format=yuv420p ${tmpFilePath}`);

    return {
        statusCode: 200,
        body: {
            result: JSON.stringify(convertOut),
        },
    };
};


  


  the signed url is fine. I've tested it with vanilla js await fetch(sourceURL) and it returned the file. The problem is that for some reason the child_process has no internet access.

  


  if anyone is able to point me in the right direction i would appreciate it :D

  


  Full error message :

  


  {
  "errorType": "Error",
  "errorMessage": "Command failed: /opt/ffmpeg -i \"https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject\" -vf scale=1080:-2,crop=1080:1350,format=yuv420p tmp/video.mp4\nffmpeg version 6.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2023 the FFmpeg developers\n  built with gcc 8 (Debian 8.3.0-6)\n  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzimg\n  libavutil      58. 29.100 / 58. 29.100\n  libavcodec     60. 31.102 / 60. 31.102\n  libavformat    60. 16.100 / 60. 16.100\n  libavdevice    60.  3.100 / 60.  3.100\n  libavfilter     9. 12.100 /  9. 12.100\n  libswscale      7.  5.100 /  7.  5.100\n  libswresample   4. 12.100 /  4. 12.100\n  libpostproc    57.  3.100 / 57.  3.100\n[tcp @ 0x141950d0] Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error\n[in#0 @ 0x14190900] Error opening input: Input/output error\nError opening input file https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject.\nError opening input files: Input/output error\n",
  "trace": [
    "Error: Command failed: /opt/ffmpeg -i \"https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject\" -vf scale=1080:-2,crop=1080:1350,format=yuv420p tmp/video.mp4",
    "ffmpeg version 6.1-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2023 the FFmpeg developers",
    "  built with gcc 8 (Debian 8.3.0-6)",
    "  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzimg",
    "  libavutil      58. 29.100 / 58. 29.100",
    "  libavcodec     60. 31.102 / 60. 31.102",
    "  libavformat    60. 16.100 / 60. 16.100",
    "  libavdevice    60.  3.100 / 60.  3.100",
    "  libavfilter     9. 12.100 /  9. 12.100",
    "  libswscale      7.  5.100 /  7.  5.100",
    "  libswresample   4. 12.100 /  4. 12.100",
    "  libpostproc    57.  3.100 / 57.  3.100",
    "[tcp @ 0x141950d0] Failed to resolve hostname my-bucket.s3.eu-central-1.amazonaws.com: System error",
    "[in#0 @ 0x14190900] Error opening input: Input/output error",
    "Error opening input file https://my-bucket.s3.eu-central-1.amazonaws.com/original/Testvideo.MOV?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential={redacted}&X-Amz-Date=20240209T212255Z&X-Amz-Expires=900&X-Amz-Security-Token={redacted}&X-Amz-Signature={redacted}&X-Amz-SignedHeaders=host&x-id=GetObject.",
    "Error opening input files: Input/output error",
    "",
    "    at ChildProcess.exithandler (node:child_process:422:12)",
    "    at ChildProcess.emit (node:events:518:28)",
    "    at maybeClose (node:internal/child_process:1105:16)",
    "    at ChildProcess._handle.onexit (node:internal/child_process:305:5)"
  ]
}
enter code here


  


  Update : Turns out it is not S3 or internet, but the child_process which does not seem to have internet access. I've update my description above.

  


• Is it a way to seek videos faster with ffmpeg while applying some filters ?

  21 mars 2023, par Peter.k

  I use parameters to cut a fragment from a video which in normal circumstances works well, but when I apply some filters, which may cause processors to be a bit busy, the seeking method seems to work very long. For example :

  


  ffmpeg -i "i:\longmovie.mp4" -vf "subtitles=longmovie.srt:force_style='FontName=Central European Time 13\:37,FontSize=20,PrimaryColour=&H00171771,OutlineColour=&HFFFFFFFF,BorderStyle=4,BackColour=&H33FFFFFF,Outline=5,Shadow=0,MarginV=10'" -b:v 1000k -ss 02:01:54.0 -to 02:02:13.0 -preset ultrafast e:/tt147+3.mp4


  


  I put those -ss and -to parameters at the end of the command, because it doesn't work in other places. It either produces very long video or skips the whole filter.

  


  Can I use some trick to make it faster. The problem is in jumping to the desired 02:01:54 time - the rest works ok.