International organisation for standardisation organisation internationale de normalisation
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- Bu səhifədəki naviqasiya:
- Review of AHG reports
- Received National Body Comments and Liaison matters
- Joint meetings
- Plenary Discussions
- 3D Audio Binauralization CE
Creation of Task GroupsTask groups were convened for the duration of the MPEG meeting, as shown in . Results of task group activities are reported below.
The Chair asked for approval of the 105rd Audio Subgroup meeting report, which was registered as a contribution. The report was approved.
There were no requests to review any of the AHG reports.
There were none.
The AHG on Dynamic Range Control (DRC) and 3D Audio and Audio Maintenance met Sunday January 12, 2013 1000-1800 hrs at the MPEG meeting venue.
Listening Test Site Reports The reports from each listening test site are listed below. Since all experts could read the reports, it was agreed that there was no need to make presentations.
The Chair presented a spreadsheet with the combined subjective data (in the zip archive of the AhG report):
The spreadsheet presents statistical analysis on each of SHORT, MEDIUM and LONG BRIRs and also gave a statistical analysis of all subjective data taken together. The identity of the systems were revealed as:
Technical Descriptions Jan Plogties, FhG-IIS and Jeongil Seo, ETRI, gave a joint presentation on
The presentation reviewed the technology for two joint proposals from the ETRI/Yonsei/WILUS and FhG-IIS. The difference is the FhG-IIS proposal used FFT-based convolution for 48 subbands, while the ETRI/Yonsei/WILUS proposal used FFT-based convolution for 32 subbands and a 1-tap delay line filter for bands 33-48. The performance of all proponent technologies was shown, both averaged over all items and for each item. This analysis was consistent with the one in the Excel spread sheet attached to the AhG report. The differences between the two systems are summarized here, where: D&E Direct and Early reflections LR Late reflections VOFF Variable Order Filtering in Frequency domain
Note 1: The first subband is number 1 (not 0). Gregory Pallone, Orange, presented
The contribution reviews the technology which is in HOA and which was in a contribution to the 106th MPEG meeting. The technology uses parameters that are obtained by a fully automatic method. In addition, it presents complexity estimations for SHORT, MEDIUM and LONG BRIRs. It documents that the automatic filter pre-processing provides the following parameters:
The presenter noted that there was a lower performance for the SHORT case. However, if the automatic processing were modified so that for BRIR length of less or equal to 4096, there was no truncation and just a direct convolution with the 558 length BRIR (and no diffuse component), then complexity for all lengths is as follows:
Jan Plogsties, FhG-IIS and Jeongil Seo, ETRI, noted that the results showed that the Orange proposal did have issues for the SHORT case, and the proposed “fix” is effectively a hand-tuned optimization. Jan Plogsties further noted that, even at high bit rates, there may be QMF domain analysis if:
Simone Fontana, Huawei, presented
The presenter noted that, compared to the technology description of the previous meeting, this proposal
The presenter noted that the system did incur some decrease in subjective quality for LONG BRIR due to the low-complexity algorithm. The presenter further noted that it is physically “incorrect” to truncate a HRTF (i.e. a BRIR measured in an anechoic environment). He envisions that the BRIR input data would have a flag indicating that it is a true HRTF or not. The technology implements the filtering in the subband domain. An automatic algorithm identifies a time-point in each subband signal that separates Early Decay Time (EDT) response and reverberant response. EDT is intended to provide “perceptually lossless” binauralization. Late Reverberation is an average over all BRIR. When the FFT complexity is 5*N*Log2(N), the system complexity is (assuming that QMF data is available):
Taegyu Lee, Yonsei, presented
The contribution notes that RM0-CO may have QMF data after core coder decoding or not, depending on the total bitrate. This appears to require the following additional complexity for binauralization:
Disussion The Chair summarized his view on the open issues:
Werner Oomen, Philips, noted that Sys2 is never worse, which suggests that the lower-complexity technology with TDL should be selected. It was the consensus of the AhG to select Sys2 (Yonsei with TDL) over Sys4 (IIS without TDL). It was the consensus of the AhG to not adopt any Sys1 (Huawei) technology at this meeting. The Chair noted that the Huawei stereo reverberant technology could be proposed as a subsequent CE. The Chair suggested to use 5*(N/2)*Log2(N) = 2.5*N*log2(N) as FFT complexity (measured in DSP operations or MACs), where
Werner Oomen, Philips and Henney Oh, WILUS, questioned why there should be two normative binaural rendering systems. This goes against the MPEG “one function, one tool” philosophy. Henney Oh, WILUS, restated the worst-case complexity analysis presented by Yonsei. Gregory Pallone, Orange, noted that two technologies for one function might be valid if they have different complexities. Jan Plogsties, FhG-IIS, stated his support for a “one function, one tool” philosophy. Failure to do this could undermine the technical credibility of MPEG 3D Audio. It was the consensus of the AhG to select Sys2 as a normative binauralization technology for RM-CO, but the specific case in which QMF data is not available needs further discussion.
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