| 1. |
- Heusdens, R., et al.
(författare)
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Bit-rate scalable intraframe sinusoidal audio coding based on rate-distortion optimization
- 2006
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Ingår i: Journal of The Audio Engineering Society. - 1549-4950. ; 54:3, s. 167-188
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Tidskriftsartikel (refereegranskat)abstract
- A coding methodology that aims at rate-distortion optimal sinusoid + noise coding of audio and speech signals is presented. The coder divides the input signal into variable-length time segments and distributes sinusoidal components over the segments such that the resulting distortion (as measured by a perceptual distortion measure) is minimized subject to a prespecified rate constraint. The coder is bit-rate scalable. For a given target bit budget it automatically adapts the segmentation and distribution of sinusoids in a rate-distortion optimal manner. The coder uses frequency-differential coding techniques in order to exploit intrasegment correlations for efficient quantization and encoding of the sinusoidal model parameters. This technique makes the coder more robust toward packet losses when used in a lossy-packet channel environment as compared to time-differential coding techniques, which are commonly used in audio or speech coders. In a subjective listening experiment the present coder showed similar or better performance than a set of four MPEG-4 coders operating at bit rates of 16, 24, 32, and 48 kbit/s, each of which was state of the art for the given target bit rate.
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| 2. |
- van Schijndel, N. H., et al.
(författare)
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Adaptive RD Optimized Hybrid Sound Coding
- 2008
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Ingår i: Journal of The Audio Engineering Society. - 1549-4950. ; 56:10, s. 787-809
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Tidskriftsartikel (refereegranskat)abstract
- Traditionally, sound codecs have been developed with a particular application in mind, their performance being optimized for specific types of input signals, such as speech or audio (music), and application constraints, such as low bit rate, high quality, or low delay. There is, however, an increasing need for more generic sound codecs, created by the emergence of heterogeneous networks and the convergence of communication and entertainment devices. To obtain such versatility, this study employs hybrid sound coding based on operational rate-distortion (RD) optimization principles. Applying this concept, a prototype coder has been implemented with emphasis on (dynamic) adaptation to the input and to application constraints. With this prototype, listening tests have been performed for different application scenarios. The results demonstrate the versatility of the concept while keeping competitive sound quality compared to dedicated state-of-the-art codecs.
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| 3. |
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| 4. |
- Mordaka, J., et al.
(författare)
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The importance of rotational kinematics in pedestrian head to windshield impacts
- 2007
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Ingår i: International Research Council on the Biomechanics of Injury - 2007 International IRCOBI Conference on the Biomechanics of Injury, Proceedings. - 2951421087 - 9782951421080 ; , s. 83-94
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Konferensbidrag (refereegranskat)abstract
- The objective of the present study was to analyze the effect of angular kinematics on head injury in pedestrian head-to-windshield impacts. Three cases of pedestrian head impacts were simulated with FE head and windshield models. The initial impact conditions were obtained from pedestrian accident reconstructions carried out using multi-body pedestrian and car models. The results from the FE head model were compared with injuries reported in the database. Maximum principal strain was chosen as the injury indicator. After successful head injury predictions, the initial velocities were varied and as a result different peak angular velocities and accelerations were simulated. The results showed that increased peak change in angular velocity caused higher maximal principal strain in the brain and in consequence higher probability of Diffuse Axonal Injury (DAI), and Acute Subdural Haematoma (ASDH). A dramatic, three-fold increase in the strain levels in the brain was found when doubling the impact velocity. This paper presents work performed within the framework of a European Commission 6 th framework project (APROSYS).
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