Recherche avancée

Sur d’autres sites (7668)

• doc/demuxers/mpegts : apply a minor grammar fix to option description

  13 août 2015, par Stefano Sabatini

  doc/demuxers/mpegts : apply a minor grammar fix to option description
  Consistently use impersonal form.
  

  • [DH] doc/demuxers.texi

• ffmpeg and php - generating thumbnail

  25 février 2014, par stinkysGTI

  I've never used ffmpeg before, but it seemed rather straight forward. I already have a script that handles the uploaded file and stores all of the relative data into the database, but I'm not able to generate a thumbnail. I don't get an error either, I even checked the error_log on the server and there was nothing. The command I'm trying to use is :

  shell_exec("/usr/bin/ffmpeg -i files/clipcanvas_14348_offline.mp4 -r 1 -s 1024x576 -f image2 -vframes 1 files/thumb_test.jpg");

  I will change the static file names with variables once I get it working because the videos that will be thumbnailed are uploaded through a form.

  I tried using the solution from this page :

  ffmpeg Getting image or thumbnail from video error

  But I'm not having any luck. Could it somehow be possible it's because it's on a sub domain ?

• Cannot decode H.264 stream (Annex.B) using FFmpeg

  15 décembre 2014, par user849642

  Recently I’m writing a client of a IP camera providing H.264 stream. I’m now using FFmpeg 2.1.1 to decode the stream provided by the camera.

  Here’s some code of the application :

  Initialization :

      private unsafe void InitFFmpeg()
  
      {
  
          FFmpeg.avcodec_register_all();
  
          var codec = FFmpeg.avcodec_find_decoder(AVCodecID.AV_CODEC_ID_H264);
  
          avcodec = (IntPtr)codec;
  
  
  
          var ctx=FFmpeg.avcodec_alloc_context3(avcodec);
  
          avcontext = (IntPtr)ctx;
  
  
  
          ctx->codec = avcodec;
  
          ctx->pix_fmt = AVPixelFormat.PIX_FMT_YUV420P;
  
          ctx->flags2 |= 0x00008000;//CODEC_FLAG2_CHUNKS
  
  
  
          var options = IntPtr.Zero;
  
          int result = FFmpeg.avcodec_open2(avcontext, avcodec, ref options);
  
          avframe = FFmpeg.av_frame_alloc();
  
          avparser = FFmpeg.av_parser_init(AVCodecID.AV_CODEC_ID_H264);
  
          FFmpeg.av_init_packet(ref avpacket);
  
          inBuffer = Marshal.AllocHGlobal(300 * 1024);
  
      }

  Decoding :

      private void Decode(byte[] data, int size)
  
      {
  
          IntPtr pOut = IntPtr.Zero;
  
          int outLen = 0;
  
  
  
          Marshal.Copy(data, 0, inBuffer, size);
  
  
  
          int gotPicture = 0;
  
  
  
          var rs = FFmpeg.av_parser_parse2(avparser, avcontext, ref pOut, ref outLen, inBuffer, size, 0, 0, 0);
  
          if (outLen <= 0 || pOut.ToInt32() <= 0)
  
          {
  
              //no enough data to construct a frame, return and receive next NAL unit.
  
              return;
  
          }
  
          avpacket.data = pOut;
  
          avpacket.size = outLen;
  
          avpacket.flags |= PacketFlags.Key;
  
          var len = FFmpeg.avcodec_decode_video2(avcontext, avframe, ref gotPicture, ref avpacket);
  
          Console.WriteLine("avcodec_decode_video2 returned " + len);
  
          if (gotPicture != 0)
  
          {
  
              //some YUV to RGB stuff
  
          }
  
      }

  With the code above, I can get some output like :

  NAL unit 1: resolution=1280x720, key-frame=True, size=26.
  
  NAL unit 2: resolution=1280x720, key-frame=False, size=8.
  
  NAL unit 3: resolution=1280x720, key-frame=False, size=97222.
  
  NAL unit 4: resolution=1280x720, key-frame=False, size=14129.
  
  avcodec_decode_video2 returned 1
  
  NAL unit 5: resolution=1280x720, key-frame=False, size=12522.
  
  NAL unit 6: resolution=1280x720, key-frame=False, size=12352.
  
  avcodec_decode_video2 returned 1
  
  NAL unit 7: resolution=1280x720, key-frame=False, size=12291.
  
  NAL unit 8: resolution=1280x720, key-frame=False, size=12182.

  From the ouput I can see the parser can recognize the NAL units sent by the camera and can construct frames from them.

  NAL unit 1 to 4 are slices of a key frame containing SPS/PPS, and the following 2 NAL units form a normal frame.

  And the avcodec_decode_video2 function doesn’t produce any error, but just keep returning 1 and gotPicture is alway 0.

  If I clear AVCodecContext.flags2, it starts to complain that the packet I provided contains no frame :

  NAL unit 100: resolution=1280x720, frame-rate=0, key-frame=True, size=26.
  
  NAL unit 101: resolution=1280x720, frame-rate=0, key-frame=False, size=8.
  
  NAL unit 102: resolution=1280x720, frame-rate=0, key-frame=False, size=96927.
  
  NAL unit 103: resolution=1280x720, frame-rate=0, key-frame=False, size=17149.
  
  [h264 @ 01423440] no frame!
  
  avcodec_decode_video2 returned -1094995529
  
  NAL unit 104: resolution=1280x720, frame-rate=0, key-frame=False, size=12636.
  
  NAL unit 105: resolution=1280x720, frame-rate=0, key-frame=False, size=12338.
  
  [h264 @ 01423440] no frame!

  If I write the raw stream to a file, I can use FFmpeg to mux the stream to an mp4 container, and can play the mp4 file with any player.

  The raw data I received is something like :

  00 00 00 01 67 42 00 28 E9 00 A0 0B 75 C4 80 03 6E E8 00 CD FE 60 0D 88 10 94
  
  00 00 00 01 68 CE 31 52
  
  00 00 00 01 65 88 81 00 06 66 36 25 11 21 2C 04 3B 81 E1 80 00 85 4B 23 9F 71...
  
  ...