Organisation internationale de normalisation

26.2.2MPEG-D Unified Speech and Audio Coding

Kristofer Kjörling, Dolby, presented

m19298

Corrections to the decoder for cross products operation

Lars Villemoes, Per Ekstrand

USAC-CORR-XP

The contribution proposed corrections to the USAC cross products tool. These are in three categories:

Reference software only, specification text is correct

• 
  Rounding of signalled pitch value. The correction is to round as the last operation. The impact of the change is decoded waveforms change by a maximum of 300*lsb.
  
• 
  Decision loop for cross-product addition. The reference software makes a decision on an incomplete series summation. The impact of the change is decoded waveforms change by a maximum of 500*lsb.
  

Changes that affect both the specification text and reference software

• 
  Twiddles in real-valued synthesis filterbank. To make conformance simpler, it is proposed to mandate the twiddle values. The result is the phase is exactly as it has been in RM0 or CE evaluation, and the point is that it will remain as such regardless of the tuning of the USAC encoder.
  
• 
  Potential out-of-bounds array indexing. Restrict index calculation such that it never becomes negative. This event ever occurred in RM0 or CE evaluation.
  

Editorial corrections to specification text

• 
  Correct one simple typo.
  

Werner Oomen, Philips, requested a breakout in which the proponent would explain the mathematics of the two twiddle configurations and how they lead to equivalent results.

Subject to a successful report from this breakout, it was the consensus of the Audio Subgroup to incorporate the proposed changes into the USAC DIS.

Kristofer Kjörling, Dolby, reported on Tuesday at 14:00hrs that the breakout occurred and all concerns were addressed.
Max Neuendorf, FhG, presented

m19319

Further Corrections to Reference Software and CD of USAC

Max Neuendorf, Markus Multrus, Christian Helmrich

USAC-CORR

The contribution proposed numerous corrections to either the Study on USAC CD text, the USAC Reference Software or both. These corrections are in three categories:

• 
  Corrections to the Study on USAC CD text (16 changes)
  
• 
  Corrections to the Reference Software (3 changes).
  
• 
  Changes to both Study on USAC CD and Reference Software (1 change)
  

Except for a single sentence in Section 3.9 of the contribution, “Clarification of Phase Coding”, it was the consensus of the Audio Subgroup to incorporate the proposed changes into the USAC DIS. This one open issue will be resolved on Tuesday at 1400 hrs.

Toru Chinen, Sony, presented

m19252

Sony listening test report on Time Warping CE

Yuki Yamamoto, Hiroyuki Honma, Toru Chinen, Masayuki Nishiguchi

USAC-TW

The contribution presents the results of a listening test, which are found in the final presentation of the pooled data.

Markus Multrus, FhG, presented

m19318

FhG listening test report on TW improvement

Stefan Bayer

USAC-TW

The contribution presents the results of a listening test, which are found in the final presentation of the pooled data.

Zhao Dan, Panasonic, presented

m19203

Finalization of CE on time warping

Zhao Dan, Zhong Haishan, Chong Kok Seng, Takeshi Norimatsu, Tomokazu Ishikawa, Neo Sua Hong

USAC-TW

The contribution presented an overview of the CE technology. The major elements of the CE technology are

• 
  Extend quantizer table for greater TW pitch tracking dynamic range
  
• 
  Huffman code quantized values for additional compression
  
• 
  Normalize the pitch coding range by the actual sampling rate in order to keep the values within the quantizer range.
  

The systems under test in the listening test are the following: