MERIT Master Thesis
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MERIT Master Thesis TITLE: Design and implementation of a loudness monitoring system AUTHOR: Jordi Cenzano Ferret DIRECTOR: Josep R. Casas Pla DATE: 17-07-2013 Design and implementation of a loudness monitoring system Page: 1 Index 1 Introduction ................................................................................................ 5 2 Loudness motivation ................................................................................. 7 3 Background and references ..................................................................... 8 3.1 Human auditory system ......................................................................................... 8 3.2 Audio: Sound into electrical world ........................................................................ 10 3.2.1 Audio impedance ....................................................................................................... 11 3.2.2 Analog level: dBu ....................................................................................................... 11 3.2.3 Digital level: dB FS .................................................................................................... 12 3.2.4 Audio level references ............................................................................................... 13 3.2.5 Dynamic range (sound and audio) ............................................................................. 14 4 Audio level meters ................................................................................... 16 4.1 Short term audio level meters .............................................................................. 16 4.1.1 Peak Program meter (or PPM)................................................................................... 16 4.1.2 Volume Unit Meter (VU-Meter)................................................................................... 17 4.1.3 True peak meter ........................................................................................................ 17 4.2 Long term audio level meters (Loudness meters) ................................................ 19 4.2.1 Zwicker loudness method .......................................................................................... 19 4.2.2 Equivalent level (Leq) ................................................................................................ 20 4.2.3 ITU-R BS.1770 .......................................................................................................... 22 4.2.4 Dobly AC-3 and Dialnorm .......................................................................................... 23 4.3 Other audio meters .............................................................................................. 25 4.3.1 Spectrum analyzers ................................................................................................... 25 4.3.2 Phase meters ............................................................................................................ 25 5 Loudness standards ................................................................................ 26 5.1 EBU Recommendation 128 ................................................................................. 26 5.2 Recommended practice A/85 .............................................................................. 28 5.3 ARIB TR-B32 ....................................................................................................... 29 6 State of the art of loudness meters ........................................................ 30 6.1 Standalone loudness meters ............................................................................... 30 6.2 Software loudness meters ................................................................................... 32 6.3 Audio mixers with loudness meters ..................................................................... 33 7 Our loudness meter implementation ..................................................... 35 7.1 Loudness Measuring Engine (LME) .................................................................... 36 7.1.1 Performance .............................................................................................................. 41 7.1.2 “EBU mode” compliance ............................................................................................ 43 7.2 Directshow wrapper ............................................................................................. 44 8 Our Loudness monitoring system (LMS) .............................................. 46 8.1 LMS introduction .................................................................................................. 46 8.2 LMS Architecture ................................................................................................. 48 8.3 Implementation issues ......................................................................................... 49 8.3.1 MySQL C++ Connector BUG ..................................................................................... 49 8.3.2 LMS time synch ......................................................................................................... 49 Design and implementation of a loudness monitoring system Page: 2 8.3.3 Microsoft Broadcast Driver Architecture stability ........................................................ 50 8.4 LMS core modules ............................................................................................... 51 8.4.1 Log to DB Module ...................................................................................................... 52 8.4.2 DTT Module ............................................................................................................... 52 8.4.3 CALC Module ............................................................................................................ 54 8.4.4 SHOW Module ........................................................................................................... 56 8.4.5 CLEAN Module .......................................................................................................... 58 8.5 LMS satellite modules ......................................................................................... 60 8.5.1 Playout change over controller module ...................................................................... 60 8.5.2 ASP SHOW Module ................................................................................................... 61 9 Example measures .................................................................................. 62 9.1 8tv ........................................................................................................................ 63 9.2 RAC105tv ............................................................................................................ 65 9.3 TV3 ...................................................................................................................... 67 9.4 Comparative of channel loudness ....................................................................... 69 9.4.1 Per channel ............................................................................................................... 69 9.4.2 Per channel and type of content ................................................................................ 70 9.4.3 Histogram and LRA ................................................................................................... 71 10 Future work .............................................................................................. 73 11 Reviewing objectives .............................................................................. 74 12 Conclusions ............................................................................................. 75 13 Acronyms table ........................................................................................ 76 14 References ............................................................................................... 77 15 Annexes .................................................................................................... 80 15.1 Manual of command line Loudness meter ........................................................... 81 15.1.1 Introduction ............................................................................................................ 82 15.1.2 Input modifiers ....................................................................................................... 82 15.1.3 Loudness configuration file .................................................................................... 83 15.1.4 Accepted input wave (.wav) formats ...................................................................... 85 15.1.5 Output wave format................................................................................................ 86 15.2 Measuring engine performance raw data ............................................................ 87 15.3 “EBU Mode” compliance test results ................................................................... 90 15.4 Manual of CJOCLoudnessDS directshow filter .................................................... 92 15.4.1 Introduction ............................................................................................................ 93 15.4.2 Input audio data ..................................................................................................... 93 15.4.3 Filter configuration parameters .............................................................................. 93 15.5 LMS Database description