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Bug #11631

raw.cxx Uncompress gives wrong results for ZeroSuppression and Huffman together

Added by David Adams over 3 years ago. Updated about 3 years ago.

Status:
Assigned
Priority:
Normal
Assignee:
Jonathan Insler
Category:
Reconstruction
Target version:
-
Start date:
02/04/2016
Due date:
% Done:

100%

Estimated time:
Occurs In:
Experiment:
-
Co-Assignees:
Duration:

Description

The utility lardata/RawData gives wrong results for the case that both zero suppression and Huffman encoding are requested. It seems the problem is this code in Uncompress:

else if(compress == raw::kZeroHuffman){
      UncompressHuffman(adc, uncompressed);
      ZeroUnsuppression(adc, uncompressed);

i.e. the uncompressed vector from the Huffman decoding is not but should be used as the input to the zero unsuppression.

When I change to this:

std::vector<short> tmp(2*adc[0]);
      UncompressHuffman(adc, tmp);
      ZeroUnsuppression(tmp, uncompressed, pedestal);

the problem goes away.

Note my guess for the size allocation of the tmp vector. UncompressHuffman requires the caller to preallocate enough space. I have already reported that in https://cdcvs.fnal.gov/redmine/issues/11572. In my case, it was not enough to use adc0 because the zero suppression increases the size of the vector.

My test showing the problem can be found here:

https://github.com/dladams/art_extensions/blob/master/test/utilities/test_Compress.cxx

History

#1 Updated by Thomas Junk over 3 years ago

  • Assignee changed from Gianluca Petrillo to Jonathan Insler

#2 Updated by Jonathan Insler over 3 years ago

  • Assignee changed from Jonathan Insler to Gianluca Petrillo
  • % Done changed from 0 to 100

David Adams wrote:

The utility lardata/RawData gives wrong results for the case that both zero suppression and Huffman encoding are requested. It seems the problem is this code in Uncompress:

else if(compress == raw::kZeroHuffman){
UncompressHuffman(adc, uncompressed);
ZeroUnsuppression(adc, uncompressed);

i.e. the uncompressed vector from the Huffman decoding is not but should be used as the input to the zero unsuppression.

When I change to this:

std::vector<short> tmp(2*adc0);
UncompressHuffman(adc, tmp);
ZeroUnsuppression(tmp, uncompressed, pedestal);

the problem goes away.

Note my guess for the size allocation of the tmp vector. UncompressHuffman requires the caller to preallocate enough space. I have already reported that in https://cdcvs.fnal.gov/redmine/issues/11572. In my case, it was not enough to use adc0 because the zero suppression increases the size of the vector.

My test showing the problem can be found here:

https://github.com/dladams/art_extensions/blob/master/test/utilities/test_Compress.cxx

Thanks to David for finding this! I have implemented his fix. This functionality was never properly tested.

#3 Updated by Jonathan Insler over 3 years ago

  • Assignee changed from Gianluca Petrillo to Jonathan Insler

#4 Updated by Gianluca Petrillo about 3 years ago

  • Status changed from New to Assigned

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