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• Why does CreateDXGIFactory occupy GPU even if I call it's release interface

  13 mai 2022, par TONY

  First I run the following code :

  


  IDXGIFactory* pFactory;
    HRESULT hr = CreateDXGIFactory(__uuidof(IDXGIFactory1), (void**)(&pFactory));
    if (FAILED(hr))
    {
        return -1;
    }


  


  then I tried to use ffmpeg's nvenc_h264 function :

  


      AVCodec* m_encoder = avcodec_find_encoder_by_name("h264_nvenc");
    if (!m_encoder) {
        m_encoder = avcodec_find_encoder_by_name("nvenc_h264");
    }

    if (!m_encoder) {
        err = -1;
        std::cout << "find 264 encoder failed" << std::endl;
        return 0;
    }

    AVCodecContext* m_encoder_ctx = avcodec_alloc_context3(m_encoder);
    if (!m_encoder_ctx) {

        err = -1;
        std::cout << "avcodec_alloc_context3 failed" << std::endl;
        return 0;
    }

    m_encoder_ctx->width = 1280;
    m_encoder_ctx->height = 720;
    m_encoder_ctx->time_base = { 1, (int)25 };

    m_encoder_ctx->codec_id = m_encoder->id;
    m_encoder_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
    m_encoder_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

    ret = avcodec_open2(m_encoder_ctx, m_encoder, nullptr);


  


  it's failed. the avcode_open2 would fail, it shows that
"[h264_nvenc @ 0000016AE3F06F00] dl_fn->cuda_dl->cuInit(0) failed -> CUDA_ERROR_NO_DEVICE : no CUDA-capable device is detected"
but if I don't call the CreateDXGIFactory, then the avcodec_open2 would success.

  


• What is a good/simple way to obtain a stream of song metadata from an online radio station ?

  29 juin 2022, par esp

  What is a good/simple way to obtain a stream of song metadata (artist names and song titles etc.) from an online radio station ? Just the metadata, not the data (media). On bash command-line for now, thinking of getting it to a database (eg MySQL) in future.

  


  I have had success using FFMpeg to do this (simply FFMpeg -i <streamurl></streamurl>). However it only reports the song playing once - when it is run. If I specify an outputfile (e.g. -f null -) then it continues to run but does not report any updates to the "now playing" metadata. If I do not specify an output file then, after reporting that metadata, it quits (which in my case is more useful !).

  


  I can imagine one way round this would be to make a polling-loop, say every 10 seconds, only reporting when the metadata has changed (since the previous time). Does anyone have a battle-tested example ?

  


  But is there a better (or cooler way) to achieve this ?

  


• Incorrect values for song length (duration) in Mp3tag after ffmpeg FLAC to MP3 conversion

  29 mars 2024, par Clueless

  The problem

  


  As per this post, I use the following command to convert a flac file to mp3 while keeping all metadata :

  


  ffmpeg -i input.flac -ab 320k -map_metadata 0 -id3v2_version 3 output.mp3


  


  When inspecting the converted mp3 file by right-clicking it, going to properties and then details, everything looks in order. The value for "Length" is correct.

  


  

  


  When inspecting the converted mp3 file with Mp3tag, the value for "Length" is different. From my testing, the "Length" value is consistently about 28% of what it is supposed to be.

  


  

  


  Normally, this isn't an issue. Most music players I use, read the correct length value, same as Windows. However, I've recently discovered that Spotify Mobile for some reason ignores the length value that can be seen in the Windows panel and uses the one that can be seen in Mp3tag.

  


  I want to figure out what command I should use so that after the flac file has been converted to mp3, Mp3tag shows the correct length, and there by, Spotify Mobile reads the correct length as well.

  


  What I have tried

  


  1.
After converting the file to Mp3, I've tried reencoding the mp3 file into a... mp3 file using the following command :

  


  ffmpeg -i original.mp3 -c:v copy -c:a mp3 -vn -ar 44100 -ac 2 -b:a 320k copy.mp3


  


  

  


  As can be seen in the image above, this fixes the issue and the length is showing correctly in Mp3tag and in Spotify Mobile.

  


  Issues with this : Reencoding reduces quality and I don't know how to combine the previous flac conversion command and this one into one line.

  


  2.
I tried https://cloudconvert.com/flac-to-mp3 and it worked. The length is displayed correctly in Mp3tag. (What commands did they use on the server ???)

  


  

  


  Issues with this : I don't want to rely on a cloud service for conversion, I have a lot of files to convert and I'd prefer it to be done locally.

  


  Some demo files

  


  Here is a folder with a flac file, a bad mp3 file (wrong length) and a good mp3 file. It looks like if you preview the music in google drive, it also plays the wrong length for the bad mp3 (39s not 2m19s), while vlc, groove player, spotify (desktop not mobile) all play the correct full length (2m19s) for the bad mp3 file.

  


  Folder : here's the link