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• Recover corrupt MTS file via ffmpeg

  24 juin 2017, par Ashley

  I have many large video files from an overseas trip. 90% of them are great, but there are a few I recorded on a dodgy SD card which are unable to play for some reason. They are all .MTS files.

  In VLC, an error appears when trying to play them :

  Unidentified codec:
  
  VLC could not identify the audio or video codec

  I don’t know much about video files or codecs, but I am savvy enough to use ffmpeg, which I thought might be my best bet.

  I attempted this on one of the files (call it ’input.MTS’) :

  ffmpeg -i input.MTS output.mp4

  The result was this :

  ffmpeg version N-82597-gd316b21 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.4.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 40.100 / 55. 40.100
  
    libavcodec     57. 66.106 / 57. 66.106
  
    libavformat    57. 58.100 / 57. 58.100
  
    libavdevice    57.  2.100 / 57.  2.100
  
    libavfilter     6. 67.100 /  6. 67.100
  
    libswscale      4.  3.101 /  4.  3.101
  
    libswresample   2.  4.100 /  2.  4.100
  
    libpostproc    54.  2.100 / 54.  2.100
  
  [adp @ 0000000000026380] Format adp detected only with low score of 25, misdetection possible!
  
  Input #0, adp, from 'input.MTS':
  
    Duration: 00:05:38.69, start: 0.000000, bitrate: 438 kb/s
  
      Stream #0:0: Audio: adpcm_dtk, 48000 Hz, stereo, s16p
  
  Output #0, mp4, to 'output.mp4':
  
    Metadata:
  
      encoder         : Lavf57.58.100
  
      Stream #0:0: Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, stereo, fltp, 128 kb/s
  
      Metadata:
  
        encoder         : Lavc57.66.106 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (adpcm_dtk (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  size=     312kB time=00:05:38.68 bitrate=   7.6kbits/s speed=33.7x
  
  video:0kB audio:250kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 25.134468%
  
  [aac @ 00000000025c5ba0] Qavg: 65531.879

  The output.mp4 file now plays in VLC without error, and is 5 minutes and 38 seconds long. However, there is no audio or video.

  Also, input.MTS is 18 MB, and output.mp4 is 0.313 MB.

  What is the correct way to recover this video ?

• Error while using h264_cuvid decoder with ffmpeg

  8 octobre 2023, par tthibalti

  I am trying to decode a video using the NVIDIA cuvid hardware acceleration with ffmpeg.

  


  I am using a NVIDIA GeForce GT 745M Graphics card (GPU:GK107), which is compatible with cuvid as specified by NVIDIA here

  


  I compiled ffmpeg with the following flags :

  


  ./configure --enable-cuda --enable-nvenc --enable-cuvid


  


  Then, I used ffmpeg with the following command line :

  


  ffmpeg.exe -hwaccel cuvid -c:v h264_cuvid -i video.mkv video.mkv


  


  ffmpeg finishes and seems to be unable to open cuvid functions :

  


  Cannot load cuvidGetDecoderCaps
[h264_cuvid @ 07047b80] Failed loading nvcuvid.
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (h264_cuvid) -> h264 (libx264))
  Stream #0:1 -> #0:1 (ac3 (native) -> vorbis (libvorbis))
  Stream #0:3 -> #0:2 (subrip (srt) -> ass (ssa))
Error while opening decoder for input stream #0:0 : Unknown error occurred


  


  In ffmpeg source code, I can find out that this error message is printed by the following macro :

  


  #define LOAD_SYMBOL(fun, tp, symbol)                                \
    do {                                                            \
        if (!((f->fun) = (tp*)dlsym(f->lib, symbol))) {             \
            av_log(NULL, AV_LOG_ERROR, "Cannot load %s\n", symbol); \
            ret = AVERROR_UNKNOWN;                                  \
            goto error;                                             \
        }                                                           \
        av_log(NULL, AV_LOG_TRACE, "Loaded sym: %s\n", symbol);     \
    } while (0)


  


  Which is called by :

  


  static inline int cuvid_load_functions(CuvidFunctions **functions)
{
    GENERIC_LOAD_FUNC_PREAMBLE(CuvidFunctions, cuvid, NVCUVID_LIBNAME);

    LOAD_SYMBOL(cuvidGetDecoderCaps, tcuvidGetDecoderCaps, "cuvidGetDecoderCaps");
    LOAD_SYMBOL(cuvidCreateDecoder, tcuvidCreateDecoder, "cuvidCreateDecoder");
    LOAD_SYMBOL(cuvidDestroyDecoder, tcuvidDestroyDecoder, "cuvidDestroyDecoder");
    LOAD_SYMBOL(cuvidDecodePicture, tcuvidDecodePicture, "cuvidDecodePicture");
#ifdef __CUVID_DEVPTR64
    LOAD_SYMBOL(cuvidMapVideoFrame, tcuvidMapVideoFrame, "cuvidMapVideoFrame64");
    LOAD_SYMBOL(cuvidUnmapVideoFrame, tcuvidUnmapVideoFrame, "cuvidUnmapVideoFrame64");
#else
    LOAD_SYMBOL(cuvidMapVideoFrame, tcuvidMapVideoFrame, "cuvidMapVideoFrame");
    LOAD_SYMBOL(cuvidUnmapVideoFrame, tcuvidUnmapVideoFrame, "cuvidUnmapVideoFrame");
#endif
    LOAD_SYMBOL(cuvidCtxLockCreate, tcuvidCtxLockCreate, "cuvidCtxLockCreate");
    LOAD_SYMBOL(cuvidCtxLockDestroy, tcuvidCtxLockDestroy, "cuvidCtxLockDestroy");
    LOAD_SYMBOL(cuvidCtxLock, tcuvidCtxLock, "cuvidCtxLock");
    LOAD_SYMBOL(cuvidCtxUnlock, tcuvidCtxUnlock, "cuvidCtxUnlock");

    LOAD_SYMBOL(cuvidCreateVideoSource, tcuvidCreateVideoSource, "cuvidCreateVideoSource");
    LOAD_SYMBOL(cuvidCreateVideoSourceW, tcuvidCreateVideoSourceW, "cuvidCreateVideoSourceW");
    LOAD_SYMBOL(cuvidDestroyVideoSource, tcuvidDestroyVideoSource, "cuvidDestroyVideoSource");
    LOAD_SYMBOL(cuvidSetVideoSourceState, tcuvidSetVideoSourceState, "cuvidSetVideoSourceState");
    LOAD_SYMBOL(cuvidGetVideoSourceState, tcuvidGetVideoSourceState, "cuvidGetVideoSourceState");
    LOAD_SYMBOL(cuvidGetSourceVideoFormat, tcuvidGetSourceVideoFormat, "cuvidGetSourceVideoFormat");
    LOAD_SYMBOL(cuvidGetSourceAudioFormat, tcuvidGetSourceAudioFormat, "cuvidGetSourceAudioFormat");
    LOAD_SYMBOL(cuvidCreateVideoParser, tcuvidCreateVideoParser, "cuvidCreateVideoParser");
    LOAD_SYMBOL(cuvidParseVideoData, tcuvidParseVideoData, "cuvidParseVideoData");
    LOAD_SYMBOL(cuvidDestroyVideoParser, tcuvidDestroyVideoParser, "cuvidDestroyVideoParser");

    GENERIC_LOAD_FUNC_FINALE(cuvid);
}


  


  Does anybody know if a specific file is needed by cuvid to load its functions ?
Any clue to what is wrong here ?

  


• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks