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About yamamoto2002

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  1. With Biphase Mark Code (BMC), clock signal and pcm digital signal is encoded to one signal. And on receiver, clock signal and pcm digital signal can be recovered by decoding BMC
  2. Fibre optic audio interfacing standard is already exists, it is called MADI. It is used at large venues like concert halls where there are many audio channels and cable length is very long IMO another standard is not necessary but it will be invented anyway From https://xkcd.com/927/
  3. On the following article, Fluke 43B Power Quality Analyzer is used to troubleshoot a power related problem. I think Linear power supply transformer of audio equipment vibrates when half-rectified AC power is inputted. https://www.fluke.com/en-th/learn/blog/power-quality/half-wave-rectifier Page 1 of the following pdf shows microphone cable noise that is induced by light dimmer. https://www.canare.co.jp/en/26B/Canare26B_Cables.pdf
  4. It is correct. FLAC encoder calculates one MD5 checksum value for the uncompressed PCM data and embed it on the header part of the FLAC file. So it is possible to calculate MD5 value for PCM data integrity by decoding and extracting entire uncompressed PCM data from the FLAC file and calculate MD5, then compare the value with embedded MD5 value on the header part of the FLAC file. Hard disk drives calculate and store ECC on every sector (fixed size data fragment) of the file. checksum is calculated on every read and when data corruption is detected, it can be corrected to
  5. @The Computer Audiophile Do you considering about recurrence prevention? For example, on new account creation, person should pass `entrance exam' of several audio related questions or something 😀
  6. Connect two DACs to PC with USB HUB . USB cannot broadcast one sound data to all connected devices: USB DAC A and USB DAC B are recognized as a separate devices from PC, and PC should send sound data to two DACs separately. Set Two USB DAC clock source to external Word Clock input. Set USB DAC A clock source to internal clock. Set USB DAC B clock source to external Word Clock input.
  7. It seems it is recorded at 48kHz. 4kHz or above frequency component contains non-musical harsh digital noise: The spectrum pattern is repeated above 4kHz, it is somewhat similar to the aliasing noise when the same digital sample value is repeated 12 times (Fig.3) ... Cutting the signal 4kHz or above (Fig.2) to alleviate this noise. Sound becomes somewhat Lo-Fi ish Delete4kHzOrAboveResult.mp3 Fig.1 Fig.2 Cut 4kHz or above frequency components Fig.3 Downsampled to 4kHz PCM and zero-order-hold upsample to create 48kH
  8. It is technically difficult, because usually each USB DAC runs its DA conversion with respective local clock crystals and those two clock crystals are free running, not synchronized each other. And sound playback position of two DACs starts to drift just after playback starts.
  9. PicoScope 4444 1000V CAT III Differential Oscilloscope Kit
  10. This explanation of PCM is not correct. PCM digital signal is discrete-time signal and it is not step shaped. And properly reconstructed analog waveform is smooth and it has no angle/edge. Here is the graphs depicting this from Richard G. Lyons, Understanding Digital Signal Processing, 3 rd Ed., Pearson, 2011, pp. 3. Figure 1-1 (a) is original analog waveform. 1-1 (b) is correct PCM digital signal representation of 1-1 (a). And 1-1 (c) is not correct! Author explains it with his words on page 4 and it is interesting read. The following is my exp
  11. I read some forum post about ECC DRAM soft error event log. In a datacenter DRAM bit upset is real problem and need to be resolved with ECC. His datacenter, which operates 1000 PCs of 24/7, observes 3 to 5 ECC soft error events (1bit flipped and safely corrected by ECC mechanism) in one month. On this case, ECC memory is must have feature. This means, if you have one PC which is used 8 hours a day sees one ECC error event in 50 years to 83 years of operation. I read somewhere, on March 2011, a datacenter near Fukushima observed more frequent than usual DRAM soft error e
  12. Thank you for your suggestion, I'll add this functionality on later versions. When multiple PlayPcmWin instance plays music simultaneously with WASAPI shared mode, sound is mixed and I think it is great 😁
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