Recherche avancée

Sur d’autres sites (9425)

• Round number of bits read to next byte

  4 décembre 2014, par watwat2014

  I have a header that can be any number of bits, and there is a variable called ByteAlign that’s calculated by subtracting the current file position from the file position at the beginning of the file, the point of this variable is to pad the header to the next complete byte. so if the header is taking up 57 bits, the ByteAlign variable needs to be 7 bits in length to pad the header to 64 bits total, or 8 bytes.

  Solutions that don’t work :

  Variable % 8 - 8, the result is the answer, but negative.

  8 % Variable ; this is completely inaccurate, and gives answers like 29, which is blatantly wrong, the largest number it should be is 7.

  how exactly do I do this ?

• Read/write to stream with JavaCV

  4 juillet 2013, par Zielony

  I'm trying to make use of JavaCV for android. I would like to create a video stream composed of screenshots. I found out that I can write a file using FFmpegFrameRecorder, but I can't write to a stream, array, buffer, or anything else, other than a file.

  Next thing is that I found a piece of code featuring custom FrameRecorder using 'avio_alloc_context' and read/write/seek callbacks. Unfortunately it's only a snippet and it's in C++. 'avio_alloc_context' method on android takes Read_packet, Read_packet and Seek callbacks, so I cannot pass a Write_packet callback. Moreover, right after 'avio_alloc_context' call, I get 'finalize' called on all objects passed to 'avio_alloc_context'.

  final VideoOutputStream videoOutputStream = new VideoOutputStream(stream);
  
  
  
  Read_packet read_packet = new Read_packet() {
  
      @Override
  
      public int call(Pointer arg0, BytePointer arg1, int arg2) {
  
          VideoOutputStream videoStream = (VideoOutputStream) arg0;
  
          try {
  
              videoStream.write(arg1.getStringBytes());
  
          } catch (IOException e) {
  
              e.printStackTrace();
  
          }
  
          return arg2;
  
      }
  
  };
  
  
  
  AVIOContext pb = avio_alloc_context(new MBytePointer(av_malloc(video_outbuf_size)), video_outbuf_size, 1,videoOutputStream, null, read_packet, null);
  
  
  
  oc.pb(pb);

  Using the above code nothing crashes nor reports errors. I just keep getting empty files.

  My question is - does anyone of you guys managed to get it working ? Do you know a correct way to initialize custom reading/writing in FrameRecorder/Grabber in JavaCV ?

• Trying to execute a SPLICE effect with libsox

  4 décembre 2012, par cube

  When two input files and one output file is required for an effect such as the splice effect, how should the sox_open_read() method be called ?

  A typical libsox routine would look something like :

  in=sox_open_read(file_path_in, NULL, NULL, NULL);
  
      out=sox_open_write(file_path_out, &in->signal, NULL, NULL, NULL, NULL);
  
  chain = sox_create_effects_chain(&in->encoding, &out->encoding);
  
  
  
  e = sox_create_effect(sox_find_effect("input"));
  
  args[0] = (char *)in, assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);
  
  
  
  assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);
  
  
  
      e = sox_create_effect(sox_find_effect("speed"));
  
      args[0] = 5,
  
      assert(sox_effect_options(e, 1, args) == SOX_SUCCESS);
  
      assert(sox_add_effect(chain, e, &in->signal, &in->signal) == SOX_SUCCESS);

  However, I want to use the splice effect which requires 2 input files to combine into one output.

  Any help would be appreciated.