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• avfilter/af_afade : improve accuracy and speed of gain computation

  25 novembre 2015, par Ganesh Ajjanagadde

  avfilter/af_afade : improve accuracy and speed of gain computation
  Gain computation for various curves was being done in a needlessly
  
  inaccurate fashion. Of course these are all subjective curves, but when
  
  a curve is advertised to the user, it should be matched as closely as
  
  possible within the limitations of libm. In particular, the constants
  
  kept here were pretty inaccurate for double precision.
  Speed improvements are mainly due to the avoidance of pow, the most
  
  notorious of the libm functions in terms of performance. To be fair, it
  
  is the GNU libm that is among the worst, but it is not really GNU libm’s fault
  
  since others simply yield a higher error as measured in ULP.
  "Magic" constants are also accordingly documented, since they take at
  
  least a minute of thought for a casual reader.
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libavfilter/af_afade.c

• problem in loading texture from AVFrame(android)

  25 mars 2013, par SieuTruc

  I get a problem when loading data from AVFrame to openGL :

   int target_width = 320;
  
                  int target_height = 240;
  
                  img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
  
                                             pCodecCtx->pix_fmt,
  
                                             target_width, target_height, PIX_FMT_RGBA, SWS_FAST_BILINEAR,
  
                                             NULL, NULL, NULL);
  
                  if(img_convert_ctx == NULL) {
  
                      LOGE("could not initialize conversion context\n");
  
                      return;
  
                  }
  
                  sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
                  //free(data);
  
                  int line=target_width*target_height*4;
  
                  data=(char*)malloc(line);
  
                  if (!data)
  
                      LOGE("create data frame fail");
  
                  LOGE("successful data");
  
                  filldata(data,pFrameRGB,target_width,target_height);

  with function filldata as :

      static void filldata(char *data,AVFrame *pFrame,int w,int h)
  
  {uint8_t *frameLine;
  
      int  yy;
  
      int i=0;
  
  
  
  for (yy = 0; yy < h; yy++) {
  
  
  
  frameLine = (uint8_t *)pFrame->data[0] + (yy * pFrame->linesize[0]);
  
  
  
  int xx;
  
  
  
  for (xx = 0; xx < w; xx++) {
  
              int in_offset = xx * 4;
  
  
  
  data[i++] = frameLine[in_offset];
  
  
  
  data[i++] = frameLine[in_offset+1];
  
  
  
  data[i++] = frameLine[in_offset+2];
  
  
  
  data[i++] = frameLine[in_offset+3];
  
          }
  
      }
  
  }

  After that i use data to transfer to

  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, *wi, *he, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*)data);

  but it cannot show texture, maybe data above and data in function gltextimage2D are different.
  Please help me figure out what is the format for gltextimage2D so i can configure data to show texture. OR anyone has some sample code to show me.

• Did not locate the video track for seeking

  5 novembre 2018, par Bruce Young

  I using android MediaPlayer to play some audios.It’s works 100% fine with the method seekTo() in some format like m4a(ffmpeg show the media info below) :
  normal is the audio file name

  But when I use other format like matroska,webm,the seekTo()method always fail !(ffmpeg show the media info below)

  seekbad is the audio file name

  Okay,when the seekTo() fail the android studio console show some logs like this :

  11-05 11:07:00.815 763-22357/? E/MatroskaExtractor: Did not locate the video track for seeking

  Than I google the logs and find out the sourcecode in google git :
  https://android.googlesource.com/platform/frameworks/av/+/304ef91624e12661e7e35c2c0c235da84a73e9c0/media/libstagefright/matroska/MatroskaExtractor.cpp

  In MatroskaExtractor.cpp some code like this :

  // Always *search* based on the video track, but finalize based on mTrackNum
  
  if (!pTP) {
  
      ALOGE("Did not locate the video track for seeking");
  
      return;
  
  }

  I do not know why my media file ’Did not locate the video track for seeking’,Does anybody know it,Thanks a lot !