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• How to use x264 for encoding with ffmpeg ?

  21 mai 2014, par mmmaaak

  I tryed to use ffmpeg for encoding video/ But it fails on initialization of AVCodecContext annd AVCodec.
  What I do :

  _codec = avcodec_find_encoder(CODEC_ID_H264);
  
  _codecContext = avcodec_alloc_context3(_codec);
  
  _codecContext->coder_type = 0;
  
  _codecContext->me_cmp|= 1;
  
  _codecContext->me_method=ME_HEX;
  
  _codecContext->me_subpel_quality = 0;
  
  _codecContext->me_range = 16;
  
  _codecContext->gop_size = 12;
  
  _codecContext->scenechange_threshold = 40;
  
  _codecContext->i_quant_factor = 0.71;
  
  _codecContext->b_frame_strategy = 1;
  
  _codecContext->qcompress = 0.5;
  
  _codecContext->qmin = 2;
  
  _codecContext->qmax = 31;
  
  _codecContext->max_qdiff = 4;
  
  _codecContext->max_b_frames = 3;
  
  _codecContext->refs = 3;
  
  _codecContext->trellis = 1;
  
  _codecContext->width = format.biWidth;
  
  _codecContext->height = format.biHeight;
  
  _codecContext->time_base.num = 1;
  
  _codecContext->time_base.den = 30;
  
  _codecContext->pix_fmt = PIX_FMT_YUV420P; 
  
  _codecContext->chromaoffset = 0;
  
  _codecContext->thread_count =1;
  
  _codecContext->bit_rate = (int)(128000.f * 0.80f);
  
  _codecContext->bit_rate_tolerance = (int) (128000.f * 0.20f);
  
  int error = avcodec_open2(_codecContext, _codec, NULL);
  
  if(error<   )
  
  {
  
      std::cout<<"Open codec fail. Error "<code>

  In such way ii fails on avopen_codec2() with :

  Program received signal SIGSEGV, Segmentation fault.
  
  [Switching to Thread 0xae1fdb70 (LWP 30675)]
  
  0xb2eb2cbb in x264_param_default () from /usr/lib/libx264.so.120

  If i comment all AVCodecContext parameters settins - I have :

  [libx264 @ 0xac75edd0] invalid width x height (0x0)

  And avcodec_open retunrs negative value. Which steps, I’m doing, are wrong ?

  Thanks for any help (ffmpeg 0.10 && libx264 daily snapshot for yesterday)

• Something missing during transcoding audio-only pieces from FLV format to AAC format ?

  21 octobre 2012, par MaiTiano

  I have ten consecutive flv pieces cut from a song in flv format. Each flv piece has about 10 seconds long.

  After I transcode these flv format audio piece into wav format by ffmpeg, I drag the new 10 wav file into foobar player and play them automatically(one-by-one played automatically). I found there is no "broken/pause" feeling in during switching from the end part of previous wav file to the start part of the next wav file.

  However, after I transcode these flv format audio piece into AAC format by ffmpeg, and do the similar listening test in the foobar player, I can hear/feel obvious breakpoint when file changing.

  Is it possible for ffmpeg to miss some audio signal during flv->aac transcoding ? Because, the transcoded aac files are supposed to be played one-by-one contiguously just like there is one file playing, in other words, there should not be the breakpoint feeling happened between two consecutive file playing !

  Any advices ? Many thanks.

• 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.