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• ffmpeg does not produce smooth videos from mkv h265

  13 décembre 2018, par user3776738

  It’s kind of subjective, but I’m not able to produce 100% smooth videos with ffmpeg.
  As input I use https://www.libde265.org/hevc-bitstreams/tos-1720x720-cfg01.mkv as a example.This is a h264 mkv video which is running really badly with my vlc player on my win7 laptop.Converting it to a h264 video let it play much better, but it still appears not to be 100% smooth. Especialy in Vegas 9 it even hangs like once a second.

  Other h264 videos even with 1080p or bigger run perfect with vlc and much better with Vegas, so it is not my laptop.

  its seems that there can be a lot of differences between h264 and h264 ??
  what could i try to make them more smooth ?

  I’m using following command to convert the video :

  ffmpeg.exe -i INPUT_FILE -ac 2 -vf scale=trunc\\(oh*a/2\\)*2:480 -c:v libx264 -sn -dn -map_metadata -1 -map_chapters -1 -profile:v high -level:v 4.0 -pix_fmt yuv420p OUTPUT_FILE  

• FFMPEG : sws_scale does not produce any data in target frame

  7 juin 2019, par Vladimir Glushkov

  I use FFMPEG to decode H264 stream. After I get decoded YUV420 frames I want to convert them into RGB24.

  struct SwsContext * ctx = NULL;
  
  
  
  // frame is AVFrame in YUV420 obtained from decoder. It has all three strides and seem to be valid.
  
  
  
  if (ctx == NULL)
  
                  {
  
                      ctx = sws_getContext(frame->width, frame->height, frame->format, frame->width, frame->height,
  
                          AV_PIX_FMT_RGB24, SWS_BICUBIC, 0, 0, 0);
  
                  }
  
  
  
              AVFrame* frame2 = av_frame_alloc();
  
  
  
              int num_bytes = av_image_get_buffer_size(AV_PIX_FMT_RGB24, frame->width, frame->height, 32);
  
  
  
              uint8_t* frame2_buffer = (uint8_t *)av_malloc(num_bytes * sizeof(uint8_t));
  
  
  
              int size = av_image_fill_arrays(frame2->data, frame2->linesize, frame2_buffer, AV_PIX_FMT_RGB24, frame->width, frame->height, 32);
  
  
  
              int height_of_output = sws_scale(ctx, frame->data, frame->linesize, 0, frame->height, frame2->data, frame2->linesize);
  
  
  
              callbackFullRGB(state, frameIndex, 0, frame2->data[0], num_bytes, (__int32)frame2->format, (__int32)frame2->width, (__int32)frame2->height);
  
  
  
              av_frame_free(&frame2);

  However frame2 has no resolution set, pixel format is -1 and data buffer is empty. I have 1280x720 input, stride length is set to 3840 for output frame which is correct. sws_scale also returns 720 as a result - no errors, no exceptions.

  What might be wrong ?

• Trying to produce a stream of OGG encoded audio originating from microphone yields a completely quiet file

  3 décembre 2019, par Dan

  Basically title. I want to produce a constant stream of audio data encoded in OGG coming from my microphone. This is my current setup :

  var mic = require('mic');
  
  var fs = require('fs');
  
  var { exec } = require('child_process')
  
  
  
  var micInstance = mic({
  
      rate: '44100',
  
      channels: '1',
  
      debug: true,
  
      exitOnSilence: 0,
  
      device: 'pulse',
  
  
  
  });
  
  
  
  var micInputStream = micInstance.getAudioStream(); 
  
  var outputFileStream = fs.createWriteStream('output.final.ogg');
  
  var transcode = exec('ffmpeg -loglevel panic -i pipe: -f ogg -')
  
  
  
  micInputStream.pipe(transcode.stdin)
  
  transcode.stdout.pipe(outputFileStream)

  When I pipe micInputStream directly to process.stdout then use a unix pipe to pipe the data to a output.wav file, I can play it back.

  When I pipe micInputStream directly to process.stdout then use a unix pipe to pipe the data to ffmpeg, then unix-pipe all that data into a output.ogg file, I can also play it back.

  But when I try my code, I get an OGG file, but when I play it back, it’s quiet.

  I’m at a loss, how do I just create a readableStream containing an endless stream of audio coming from the mic, encoded in OGG ?