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METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN
METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN
Schedule
Schedule
Wow & flutter – parasite effects
Wow & flutter – parasite effects
Wow & Flutter problem
Wow & Flutter problem
Standards related with wow & flutter
Standards related with wow & flutter
Wow Restoration algorithms
Wow Restoration algorithms
PrestoSpace partnership
PrestoSpace partnership
Methods of the restoration of pitch variation defects based on
Methods of the restoration of pitch variation defects based on
Methods of the restoration of pitch variation defects based on one
Methods of the restoration of pitch variation defects based on one
Methods of the restoration of pitch variation defects based on one
Methods of the restoration of pitch variation defects based on one
Our algorithms…
Our algorithms…
Carrier feature analysis
Carrier feature analysis
Wow Restoration Plugin
Wow Restoration Plugin
Conclusions
Conclusions
METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN
METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN

Презентация на тему: «METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN AUDIO RECORDINGS». Автор: . Файл: «METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN AUDIO RECORDINGS.ppt». Размер zip-архива: 942 КБ.

METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN AUDIO RECORDINGS

содержание презентации «METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN AUDIO RECORDINGS.ppt»
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1 METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN

METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN

AUDIO RECORDINGS

Multimedia Systems Department Gda?sk University of Technology (GUT) Poland

CZYZEWSKI A., MAZIEWSKI P., DZIUBINSKI M., KACZMAREK A., KULESZA M., CIARKOWSKI A. & KOSTEK B.

2 Schedule

Schedule

Wow & flutter – basic facts and definitions Methods of estimating parasitic frequency modulation in audio Our algorithms and software Sound examples Conclusions

3 Wow & flutter – parasite effects

Wow & flutter – parasite effects

The wow & flutter defects can be found in: Recordings, especially archival on magnetic and optical sound tapes Those defects can occur during: sound recording copying procedure The main sources of those defects are: irregular velocity of the sound carrier movement mechanical tape damages Parasite wow (flutter) distortions can be characterised as an undesirable changes of all sound frequency components Eliminating them should help to understand the content of some still unresolved archival speech recordings

4 Wow & Flutter problem

Wow & Flutter problem

Drift fmod < 0.5Hz Wow fmod ? < 0.5 – 6Hz > Flutter fmod ? < 6Hz – 100Hz > Frequency-modulation noise fmod > 100Hz

5 Standards related with wow & flutter

Standards related with wow & flutter

Examples of well known standards : Magnetic Tape Recording and Reproducing (Reel-to-Reel) NAB Standard 1965 (National Association of Broadcasters) Messgerate fur Frequenzschwankungen bei Schallspeichergeraten (Measuring Equipment for Frequency Variations in Sound Recording Equipment) DIN 1966 Measurement of Wow and Flutter in Recording Equipment and in Sound Reproduction CCIR Recommendation 1970 Method for Measurement of Weighted Peak Flutter of Sound Recording and Reproducing Equipment IEEE 1953 (1971) AES 1982 (2003)

It is generally accepted that flutter should be less than 0.15% DIN weighted to be inaudible. Measurement methods (2) are described in IEC 386, and a suitable test film is available from the SMPTE (No. P35-FL).

6 Wow Restoration algorithms

Wow Restoration algorithms

The defect is difficult to estimate and to restore We developed several algorithms for wow restoration

7 PrestoSpace partnership

PrestoSpace partnership

Preservation towards storage and access. Standardised Practices for Audiovisual Contents in Europe FP6-IST-707336

Coordinator : INA Project Steering Board : BBC, RAI, INA, ORF, Joanneum Research (Austria), B&G (NL), Sheffield University (GB) Partners : CTM Debrie, ACS, Media-Matters, CRCDG, Centrimage, Vectracom, SWR, Front Porch Digital, Hi-STor, Houpert Digital Audio, LIMSI-CNRS, Snell&Wilcox, TI Partners, Universities… Three partners to be identified in second phase of the project External User Group : 30+ considered archives.

8 Methods of the restoration of pitch variation defects based on

Methods of the restoration of pitch variation defects based on

comparison of the multiple copies of degraded audio

time warping algorithms applied in time or spectral domain (appropriate algorithm should generate the correct time warping function or pitch variation function). adaptive filtering (estimation of time delay (offset) between selected copies). correlation methods (finding similarities based on cross-correlation function). statistical methods (maximum likelihood estimation or true Bayesian estimation – depending on knowing the priori information).

9 Methods of the restoration of pitch variation defects based on one

Methods of the restoration of pitch variation defects based on one

copy of the archive recording

speech applications – lowpass filtering followed by pattern matching. speech - cepstral analysis which reveals information about the fundamental frequency. music or speech - application of methods based on a knowledge of the shape of the nonlinear function of audio distortion. PVC = Pitch Variation Curve

10 Methods of the restoration of pitch variation defects based on one

Methods of the restoration of pitch variation defects based on one

copy of the archive recording

multiple pitch tracking based on : McAulay and Quatieri representation (pitch tracking through the use of multiple concurrent pitch “tracks”) Analyzing high-frequency bias Analyzing recorded power-line hum (AC power supply) pitch tracking algorithms should generate the correct pitch variation function (PVC) based on pitch variation the restoration of the signal can be done for example by resampling it with a truncated sinc function.

11 Our algorithms…

Our algorithms…

presto8.exe (7)

12 Carrier feature analysis

Carrier feature analysis

Tracking power-line hum frequency Hum is commonly found in archival recordings. Tracking its frequency allows estimating the depth of wow effect. Due to limitations of DFT methods in case of low-frequency signals, the AR pseudospectrum estimation method is used. Tracking high-frequency bias Assuming that a high frequency bias was recorded on the magnetic tape it could serve as an ideal target for parasite wow characteristic determining. This idea was also exploited in the prepared software.

13 Wow Restoration Plugin

Wow Restoration Plugin

No Wow

O R I G I N A L

R E S T O R E D

Wow

14 Conclusions

Conclusions

MQ analysis can be effective in case of parasite frequency modulation detection Formant structure analysis can significantly improve efficiency of the detection process Precise wow tracking can be achieved based on a cepstrally smoothed spectrum representation Recorded power line hum provides a good basis for wow tracking (similarly to high-frequency bias in magnetic recordings) Interactive procedures (parameters adjustment) leads to more reliable results It seems that an interactive approach employing an algorithmic „toolbox” for wow&flutter restoration is the best solution of this problem

15 METHODS FOR DETECTION AND REMOVAL OF PARASITIC FREQUENCY MODULATION IN
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