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• not able to convert a specific .wav file to mp3 or m4a with sox, avconv

  25 juillet 2017, par astrograph

  At the office we have a project where we apply IoT technologies to a real bee hive.

  One of the features is to detect specific sounds the bees make when a new queen hatches. We have a special microphone in place, the algorithm is also implemented. For now we get a lot of false positives, and want to quickly be able to identify them, by listening to the audio files in the browser. Therefore I want to convert the .wav files to either .mp3 or .m4a

  The .wav file format seems to be quite strange, as I was not able to convert it to mp3 using avconv, sox or even audacity. The funny thing is, the Microsoft media player can play the .wav file fine.

  Here is the information soxi gives about the wav file :

  pi@raspberrypi:~ $ soxi Channel1.wav
  
  soxi WARN wav: wave header missing extended part of fmt chunk
  
  
  
  Input File     : 'Channel1.wav'
  
  Channels       : 1
  
  Sample Rate    : 6250
  
  Precision      : 24-bit
  
  Duration       : 00:01:21.00 = 506250 samples ~ 6075 CDDA sectors
  
  File Size      : 2.03M
  
  Bit Rate       : 200k
  
  Sample Encoding: 32-bit Floating Point PCM

  This is the avconv command I am trying to use :

  avconv -y -v quiet -i Channel1.wav -strict experimental -ar 44100 -ab 160k Channel1.m4a

  I also tried with sox :

  sox  -v 0.60 Channel1.wav -r 22050 Channel1.m4a

  but the output is mostly silent, with some random noise.

  The question is how can a wav file like this : https://drive.google.com/open?id=0B9YVh-jkOMLsQThERlI2emN2QWM be converted to an audio format using a raspberry pi that can be played in the browser ?

• Failed to execute : 0x80070057, when decoding video via ffmpeg with dxva2

  25 mars 2019, par CD83

  I have successfully implemented a video player using ffmpeg. I am now trying to use hardware decoding but I’m facing a couple issues.
  I found a post that I followed as a starting point here : https://ffmpeg.org/pipermail/libav-user/2014-August/007323.html

  I have updated the code that setup the necessary stuff for the decoder. The updated code is available here : https://drive.google.com/file/d/0B5ufHdoDzA4ieVk5UVpxcDNzRHc/view?usp=sharing

  And this is how I’m using it to initialize the decoder :

  // Prepare the decoding context
  
  AVCodec *codec = nullptr;
  
  _codecContext = _avFormatContext->streams[_streamIndex]->codec;
  
  if ((codec = avcodec_find_decoder(_codecContext->codec_id)) == 0)
  
  {
  
      std::cout << "Unsupported video codec!" << std::endl;
  
      return false;
  
  }
  
  
  
  _codecContext->thread_count = 1;  // Multithreading is apparently not compatible with hardware decoding
  
  InputStream *ist = new InputStream();
  
  ist->hwaccel_id = HWACCEL_AUTO;
  
  ist->hwaccel_device = "dxva2";
  
  ist->dec = codec;
  
  ist->dec_ctx = _codecContext;
  
  _codecContext->coded_width = _width;
  
  _codecContext->coded_height = _height;
  
  
  
  _codecContext->opaque = ist;
  
  dxva2_init(_codecContext);
  
  
  
  _codecContext->get_buffer2 = ist->hwaccel_get_buffer;
  
  _codecContext->get_format = GetHwFormat;
  
  _codecContext->thread_safe_callbacks = 1;
  
  
  
  if (avcodec_open2(_codecContext, codec, nullptr) < 0)
  
  {
  
      std::cout << "Video codec open error" << std::endl;
  
      return false;
  
  }

  And here is the definition of GetHwFormat referenced above :

  AVPixelFormat GetHwFormat(AVCodecContext *s, const AVPixelFormat *pix_fmts)
  
  {
  
      InputStream* ist = (InputStream*)s->opaque;
  
      ist->active_hwaccel_id = HWACCEL_DXVA2;
  
      ist->hwaccel_pix_fmt = AV_PIX_FMT_DXVA2_VLD;
  
      return ist->hwaccel_pix_fmt;
  
  }

  When I open an mp4 (encoded in h264) video that is HD resolution or less, everything seems to be working fine. However, as soon as I try higher resolution videos like 3840x2160, I get the following errors repeatedly :

  Failed to execute: 0x80070057
  
  Hardware accelerator failed to decode picture

  I also start getting the following errors after a few seconds :

  co located POCs unavailable

  And the video is not displayed properly : I get a lot of artifacts all over the video and it is lagging. I checked the first error in the ffmpeg source code. It seems that IDirectXVideoDecoder_Execute fails because of an invalid parameter. Since this is happening withing ffmpeg, there must be something that I’m missing but I can’t figure out what. The only relevant post that I found with this error was because of multithreading but I set the thread_count to 1 before opening the codec.

  This issue is happening on my main computer which has the following specs :

  • i7-4790 CPU @ 3.6GHz
  • RAM 16 GB
  • Intel HD Graphics 4600
  • Windows 8.1

  The same issue is not happening on my second computer which has the following specs :

  • i7 4510U @ 2GHz
  • RAM 8 GB
  • NVIDIA GeForce GTX 750Ti
  • Windows 10

  If I use DXVAChecker on my main computer, it says that my graphics card supports DXVA2 for H264_VLD_*, and I can see that the calls to the Microsoft API are being made (DXVA2_DecodeDeviceCreated, DXVA2_DecodeDeviceBeginFrame, DXVA2_DecodeDeviceGetBuffer, DXVA2_DecodeDeviceExecute, DXVA2_DecodeDeviceEndFrame) while my video is playing.

  I also don’t see any increase of GPU usage (on either computer) between the version with hardware decoding and the version without ; however, I do see a decrease in CPU usage (not as much as I was expecting though). This is also very strange.

  Note that I tried both the Windows release available on the FFmpeg website, and a version that I compiled with —enable-dxva2. I have searched a lot already but I was unable to find what I’m doing wrong.

  Hopefully, someone can help me, or maybe point me to a better example ?

• FFMPEG drops supposedly corrupt frames from original video while transcoding using h264 encoder

  19 février 2019, par t6nand

  I am using h264 for optimising MP4 for web. I have a video which has some supposedly corrupt frame(s) within it’s initial 1-2 seconds. (Frame provided below)

  On transcoding using :

  ffmpeg -i orig.mp4 -c:v libx264 -crf 25 -vf scale="-2:min(ih\,720)" -b:v 600K -g 90 -c:a libfdk_aac output.mp4

  The output MP4 has these frames dropped out and I have my output with it’s start about 1 to 2 seconds delayed from original video, thus resulting in overall less time duration in output video.

  Moreover, most media players also skip these frames in playback (like quicktime player, etc). But VLC media player was able to play this video without skipping these frames.

  Is there a way to not drop frames using ffmpeg ? And if possible is it possible to identify and fix these frames in a video ?

  Note : I tried encoding same video using AWS Elastic transcoder which actually fixed these frames (Frame provided below) :
  

  Note : Original video can be found here -
  https://drive.google.com/file/d/0B9VkhR9Zu60ybXFDeno3RGpQTUE/view?usp=sharing
  Video transcoded by AWS Elsatic transcoder can be found here -
  https://drive.google.com/file/d/0B9VkhR9Zu60yWUVHQk5MTk05QVk/view?usp=sharing

  EDIT1 : As suggested by @Mulvya in comments, TS-transcoded video can be found here - (https://drive.google.com/file/d/0B9VkhR9Zu60yU0t6T0dMME9ZMmc/view?usp=sharing)