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• 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.

• ffmpeg buffer not released

  11 mars 2013, par ByteByter

  So, I have written a basic decoder for ffmpeg that simply reads the input frames pixel data (Stored using RGB 8 format), and places it directly into the output buffer. (Also RGB 8) The problem is that when I use this decoder in ffmpeg, it says that there is 1 unreleased buffer.(Tested using ffmpeg -i Test.utah Test.png). Unfortunately, I am unsure of what buffer it is talking about, as I am not creating my own buffer. I have tried releasing the AVContext's coded_frame buffer in my decoders closing method, but this causes segmentation faults.

  Any help would be greatly appreciated.

  static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPacket *avpkt)
  
  {
  
      int ret;           /*Hold return from get_buffer */ 
  
      int skipSize;      /*Number of dummy bytes to skip per line*/
  
      int fseek=8;       /*Location of the first pixel*/
  
      int i=0; int j=0;  /*Output buffer seek index/Input Buffer seek index*/
  
      const uint8_t *buf = avpkt->data; /*Hold a pointer to the input buffer*/
  
      AVFrame *pict=data; /*Hold a pointer to the output buffer*/
  
  
  
      /*Set the output pixel format to RGB8*/
  
      avctx->pix_fmt = AV_PIX_FMT_RGB8;
  
  
  
      /*Get the width and height*/
  
      bytestream_get_le32(&buf);
  
      avctx->width=bytestream_get_le16(&buf);
  
      avctx->height=bytestream_get_le16(&buf);
  
  
  
      /*Release the old buffer*/
  
      if (pict->data[0]) avctx->release_buffer(avctx, pict);
  
  
  
      /*Aquire a large enough data buffer to hold the decompressed picture*/
  
      if (ret=ff_get_buffer(avctx, pict) < 0) return ret;
  
      skipSize=pict->linesize[0] - avctx->width; 
  
  
  
      /*Transfer input buffer to output buffer*/
  
      for(int y=0;yheight;y++){
  
          for(int x=0;xwidth;x++){
  
              pict->data[0][i]=avpkt->data[fseek+j];
  
              j++;
  
              i++;
  
          }
  
          i+=skipSize;
  
      }
  
  
  
      /*Inform ffmpeg the output is a key frame and that it is ready for external usage*/
  
      pict->pict_type        = AV_PICTURE_TYPE_I;
  
      pict->key_frame        = 1;
  
      *got_frame=1;
  
      return 0;
  
  }

• How to avoid audio sample 16bit clipping after equalization ?

  28 mai 2013, par testCoder

  I have samples which come from ffmpeg, very often it is 16 bit samples (short type), i have used iir band pass filter with dbGain as described here, after filtering i sometimes got a short type overflow and result of it is some noise when calculated sample value go out from 32767/-32767, Is any way to escape audio pcm sample clipping. May be exists any approaches ?

  I have googled but not found any worked example ?

  UPDATE

  When i cast transfer function calculation result to integer and check overflow then noise still occurs: :

  int result = A1 * ((int) Rx) + A2 * ((int) Rxx) + A3 * ((int) Rxxx)
  
                      - B1 * ((int) Ryy) - B2 * ((int) Ryyy);
  
  if (result > 32767)
  
      result = 32767;
  
  if (result < -32700)
  
      result = -32700;
  
  y = (short) result;