LegacyBlockFile.h File Reference

#include "../BlockFile.h"

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Classes
class	LegacyBlockFile
	Audacity 1.1.0 block file format: More...

Functions
void	ComputeLegacySummaryInfo (const wxFileName &fileName, size_t summaryLen, sampleFormat format, SummaryInfo *info, bool noRMS, bool Silent, float *min, float *max, float *rms)

Function Documentation

ComputeLegacySummaryInfo()

void ComputeLegacySummaryInfo	(	const wxFileName &	fileName,
		size_t	summaryLen,
		sampleFormat	format,
		SummaryInfo *	info,
		bool	noRMS,
		bool	Silent,
		float *	min,
		float *	max,
		float *	rms
	)

Definition at line 38 of file LegacyBlockFile.cpp.

{
   int fields = 3; /* min, max, rms */
 
   if (noRMS)
      fields = 2;
 
   info->fields = fields;
   info->format = format;
   info->bytesPerFrame =
      SAMPLE_SIZE(info->format) * fields;
   info->totalSummaryBytes = summaryLen;
   info->offset64K = 20; /* legacy header tag len */
   info->frames64K = (summaryLen-20) /
      (info->bytesPerFrame * 256);
   info->offset256 = info->offset64K +
      (info->frames64K * info->bytesPerFrame);
   info->frames256 =
      (summaryLen - 20 -
       (info->frames64K * info->bytesPerFrame)) /
      info->bytesPerFrame;
 
   //
   // Compute the min, max, and RMS of the block from the
   // 64K summary data
   //
 
   Floats summary{ info->frames64K * fields };
   SampleBuffer data(info->frames64K * fields,
      info->format);
 
   int read;
   {
      Optional<wxLogNull> silence{};
      const wxString fullPath{ fileName.GetFullPath() };
      wxFFile summaryFile(fullPath, wxT("rb"));
      if (Silent)
         silence.emplace();
 
      // FIXME: TRAP_ERR no report to user of absent summary files.
      if (!summaryFile.IsOpened()) {
         wxLogWarning(wxT("Unable to access summary file %s; substituting silence for remainder of session"),
            fullPath);
 
         read = info->frames64K * info->bytesPerFrame;
         memset(data.ptr(), 0, read);
      }
      else{
         // FIXME: TRAP_ERR Seek in summary file could fail.
         summaryFile.Seek(info->offset64K);
         read = summaryFile.Read(data.ptr(),
            info->frames64K *
            info->bytesPerFrame);
      }
   }
 
   int count = read / info->bytesPerFrame;
 
   CopySamples(data.ptr(), info->format,
               (samplePtr)summary.get(), floatSample, count);
 
   (*min) = FLT_MAX;
   (*max) = FLT_MIN;
   float sumsq = 0;
 
   for(int i=0; i<count; i++) {
      if (summary[fields*i] < (*min))
         (*min) = summary[fields*i];
      if (summary[fields*i+1] > (*max))
         (*max) = summary[fields*i+1];
      if (fields >= 3)
         sumsq += summary[fields*i+2]*summary[fields*i+2];
   }
   if (fields >= 3)
      (*rms) = sqrt(sumsq / count);
   else
      (*rms) = 0;
}

References CopySamples(), floatSample, format, min(), SampleBuffer::ptr(), and SAMPLE_SIZE.

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