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• FFmpeg giving a wierd "Permission denied" error (Digitalocean VPS Ubuntu 18.04)

  10 mai 2021, par DJ Danny

  I've set up a VPS server on Digitalocean. Installed Ubuntu 18.04, LAMP, etc.
Finally, I installed ffmpeg. It is working fine from terminal but when I try to execute it through php it gives a weird "Permission denied" error :

  


  Here is some information :

  
root@vl :/# whereis ffmpeg
  
ffmpeg : /usr/local/bin/ffmpeg
  
root@vl :/# whereis ffprobe
  
ffprobe : /usr/local/bin/ffprobe
  

  


  root@vl :/# ffmpeg -version
  
ffmpeg version N-102461-g8649f5dca6 Copyright (c) 2000-2021 the FFmpeg developers
built with gcc 7 (Ubuntu 7.5.0-3ubuntu1 18.04)
configuration : —prefix=/usr/local/ffmpeg_build —pkg-config-flags=—static —extra-cflags=-I/usr/local/ffmpeg_build/include —extra-ldflags=-L/usr/local/ffmpeg_build/lib —extra-libs='-lpthread -lm' —ld=g++ —bindir=/usr/local/bin —enable-gpl —enable-gnutls —enable-libaom —enable-libass —enable-libfdk-aac —enable-libfreetype —enable-libmp3lame —enable-libopus —enable-libsvtav1 —enable-libvorbis —enable-libvpx —enable-libx264 —enable-libx265 —enable-nonfree
libavutil 57. 0.100 / 57. 0.100
libavcodec 59. 1.100 / 59. 1.100
libavformat 59. 0.101 / 59. 0.101
libavdevice 59. 0.100 / 59. 0.100
libavfilter 8. 0.101 / 8. 0.101
libswscale 6. 0.100 / 6. 0.100
libswresample 4. 0.100 / 4. 0.100
libpostproc 56. 0.100 / 56. 0.100


  


  My php file :
  

  

echo shell_exec("ffmpeg -i mj.gif -profile:v baseline -pix_fmt yuv420p -vf scale=600 :-2 output.mp4 2>&1")
  
 ?>

  


  The ERROR ! :
  
ffmpeg version N-102461-g8649f5dca6 Copyright (c) 2000-2021 the FFmpeg developers built with gcc 7 (Ubuntu 7.5.0-3ubuntu1 18.04) configuration : —prefix=/usr/local/ffmpeg_build —pkg-config-flags=—static —extra-cflags=-I/usr/local/ffmpeg_build/include —extra-ldflags=-L/usr/local/ffmpeg_build/lib —extra-libs='-lpthread -lm' —ld=g++ —bindir=/usr/local/bin —enable-gpl —enable-gnutls —enable-libaom —enable-libass —enable-libfdk-aac —enable-libfreetype —enable-libmp3lame —enable-libopus —enable-libsvtav1 —enable-libvorbis —enable-libvpx —enable-libx264 —enable-libx265 —enable-nonfree libavutil 57. 0.100 / 57. 0.100 libavcodec 59. 1.100 / 59. 1.100 libavformat 59. 0.101 / 59. 0.101 libavdevice 59. 0.100 / 59. 0.100 libavfilter 8. 0.101 / 8. 0.101 libswscale 6. 0.100 / 6. 0.100 libswresample 4. 0.100 / 4. 0.100 libpostproc 56. 0.100 / 56. 0.100 Input #0, gif, from 'mj.gif' : Duration : 00:00:01.60, start : 0.000000, bitrate : 22863 kb/s Stream #0:0 : Video : gif, bgra, 1400x1050, 10 fps, 10 tbr, 100 tbn output.mp4 : Permission denied


  
From the past 24 hours I've tried installing ffmpeg in different ways (compiling & apt install), I've also tried changing the permission but still I'm stuck with this error.
  
Any help would be highly appreciated !
  
Thanks

  


• NodeJS - efficiently and correctly convert from raw PCM to WAV at scale (without FFMPEG ?)

  13 juillet 2024, par Royi Bernthal

  I have a stream of raw PCM buffers I need to convert to playable WAV buffers.

  


  @ffmpeg.wasm can convert an individual buffer in the stream well, but it's limited to executing 1 command at a time, so it won't work in a real-life streaming scenario (streams x concurrent users). We can use it as a reference to a conversion that outputs a good playable wav.

  


  import { FFmpeg, createFFmpeg, fetchFile } from '@ffmpeg.wasm/main';

async pcmToWavFFMPEG(buffer: Buffer) {
    // bitDepth - PCM signed 16-bit little-endian
    const options = { sampleRate: '24k', channels: '1', bitDepth: 's16le' };

    this.ffmpeg.FS('writeFile', 'input.pcm', await fetchFile(buffer));

    await this.ffmpeg.run(
      '-f',
      options.bitDepth,
      '-ar',
      options.sampleRate,
      '-ac',
      options.channels,
      '-i',
      'input.pcm',
      'output.wav',
    );

    const wavBuffer = this.ffmpeg.FS('readFile', 'output.wav');

    this.ffmpeg.FS('unlink', `input.pcm`);
    this.ffmpeg.FS('unlink', `output.wav`);

    return Buffer.from(wavBuffer);
  }


  


  In order to get over the command execution limit, I've tried fluent-ffmpeg. I couldn't find a way to convert a single buffer, so I'm just passing the whole readable stream so that ffmpeg can convert all of its buffers to wav. The buffers I'm getting in on('data') aren't playable wav. The same is true for concatting the accumulated buffers in on('complete') - the result is not a playable wav.

  


  import ffmpeg from 'fluent-ffmpeg';
import internal from 'stream';

async pcmToWavFluentFFMPEG(
    readable: internal.Readable,
    callback: (chunk: Buffer) => void,
  ) {
    const options = { sampleRate: 24000, channels: 1, bitDepth: 's16le' };

    ffmpeg(readable)
      .inputFormat(options.bitDepth)
      .audioFrequency(options.sampleRate)
      .audioChannels(options.channels)
      .outputFormat('wav')
      .pipe()
      .on('data', callback);
  }


  


  I've also tried using node-wav to convert each buffer individually. It manages to convert everything to playable wavs that sound close to the desired result, however for some reason they're extremely loud and sound a bit weird.

  


  import wav from 'node-wav';

pcmToWavBad(buffer: Buffer) {
    const pcmData = new Int16Array(
      buffer.buffer,
      buffer.byteOffset,
      buffer.byteLength / Int16Array.BYTES_PER_ELEMENT,
    );

    const channelData = [pcmData]; // assuming mono channel

    return wav.encode(channelData, { sampleRate: 24000, bitDepth: 16 });
  }


  


  I've also tried wrapping the PCM as a WAV with wavefile without any actual conversion (which is redundant as PCM is contained as is in WAV), but it results in white noise :

  


  import { WaveFile } from 'wavefile';

pcmToWav(buffer: Buffer) {
    const wav = new WaveFile();

    wav.fromScratch(1, 24000, '16', buffer); // 's16le' is invalid

    return Buffer.from(wav.toBuffer());
  }


  


• FFmpeg avcodec_encode_video2 access violation

  28 février 2016, par JustPingo

  I’ve been trying to encode a frame using FFmpeg with Visual C++. Here is how I do it.
  I first have a planar RGB24 image buffer. I convert it to planar YUV using the following rule :

  Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
  
  U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
  
  V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;

  I implemented it like this :

  void rgb8toYuv(uchar* rgb, uchar* yuv, uint pixelAmount) {
  
      uchar r, g, b;
  
      for (uint i = 0; i < pixelAmount; i++) {
  
          r = rgb[3 * i];
  
          g = rgb[3 * i + 1];
  
          b = rgb[3 * i + 2];
  
          yuv[3 * i] = ((66 * r + 129 * g + 25 * b + 128) >> 8) + 16;
  
          yuv[3 * i + 1] = ((-38 * r - 74 * g + 112 * b + 128) >> 8) + 128;
  
          yuv[3 * i + 2] = ((112 * r - 94 * g - 18 * b + 128) >> 8) + 128;
  
      }
  
  }

  I open everything like this (I’m using malloc because I’m used to it in C and it’s my first C++ program, I guess it shouldn’t cause any problem ?) :

  AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  AVFormatContext* outContext;
  
  avformat_alloc_output_context2(&outContext, NULL, "mp4", filepath);
  
  
  
  AVStream* video = avformat_new_stream(outContext, codec);
  
  video->codec->bit_rate = VIDEOBITRATE;
  
  video->codec->width = VIDEOWIDTH;
  
  video->codec->height = VIDEOHEIGHT;
  
  video->time_base = fps;
  
  video->codec->gop_size = 10;
  
  video->codec->max_b_frames = 1;
  
  video->codec->pix_fmt = AV_PIX_FMT_YUV420P;
  
  video->codec->codec_id = AV_CODEC_ID_H264;
  
  video->codec->codec_type = AVMEDIA_TYPE_VIDEO;
  
  
  
  avio_open(&outContext->pb, filepath, AVIO_FLAG_READ_WRITE);
  
  avformat_write_header(outContext, NULL);
  
  
  
  AVFrame* frame = av_frame_alloc();
  
  frame->width = VIDEOWIDTH;
  
  frame->height = VIDEOHEIGHT;
  
  frame->format = AV_PIX_FMT_YUV420P;

  Then, here is the function I use to encode a frame :

  void encodeFrame(uint currentFrame, uchar* data) { // RGB data
  
      uchar* yuvData = (uchar*) malloc(videoWidth * videoHeight * 3);
  
      rgb8toYuv(data, yuvData, videoWidth * videoHeight);
  
      av_image_fill_arrays(frame->data, frame->linesize, yuvData, AV_PIX_FMT_YUV420P, videoWidth, videoHeight, 3); // I'm not sure about that 3, I couldn't find any documentation about it
  
  
  
      AVPacket* packet = (AVPacket*) malloc(sizeof(AVPacket));
  
      memset(packet, 0, sizeof(AVPacket));
  
      av_init_packet(packet);
  
      packet->data = NULL;
  
      packet->size = 0;
  
  
  
      frame->pts = currentFrame; // I don't know if this is corrrect too
  
      avcodec_encode_video2(video->codec, packet, frame, NULL);
  
      av_interleaved_write_frame(outContext, packet);
  
      av_packet_unref(packet);
  
  
  
      free(yuvData);
  
      free(packet);
  
  }

  However, this causes an Access violation writing location 0x00000000 on avcodec_encode_video2. I checked the errors returned by every of FFmpeg’s functions, and it seems like they all work except av_image_fill_arrays that returns a weird 1382400 error, although according to the debugger’s RAM-viewing tool, everything gets filled correctly.

  It seems like avcodec_encode_video2 tries to access a NULL object that shouldn’t be, however I can’t find what it could be, as I followed a lot of sources example, and I don’t know what I did wrong.

  Thanks in advance !

  EDIT : After applying the fix suggested by Edgar Rokyan (which is setting the 4th argument to an int pointer), I now get an access violation on 0x00000024, still with avformat_alloc_output_context2. I believe the problem is similar, but I still can’t find anything.