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yamamoto2002

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About yamamoto2002

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  1. Perhaps the SD card advertise 128GB capacity to host computer but actual size is 8GB, 16GB or 32GB. Run H2testw to see actual size of the SD card
  2. You may be relieved to hear there is only Do, Do♯, Re and Re♯ between 16kHz to 20kHz 14,080Hz A La 14,917Hz B(A♯) La♯ 15,804Hz H Si 16,744Hz C Do 17,739Hz C♯ Do♯ 18,794Hz D Re 19,912Hz D♯ Re♯ 21,096Hz E Mi 22,350Hz F Fa 23,679Hz F♯ Fa♯ 25,087Hz G Sol 26,579Hz G♯ Sol♯ 28,160Hz A La
  3. Measurement is interesting. It shows engineers' design decision. Sometimes it is trade-off. Also sometimes it shows glitch. Even if the noise caused by the glitch is well below the hearing threshold, it is better to be glitch-free IMO. Here it is example of my coding bug. The periodical click noise and ultrasonic tone is below hearing threshold but the graph implies off-by-1 error in my 2x upsample program 😁
  4. I created a player app program to read the file and prepare all the uncompressed PCM data to play before playback starts. Full source code is disclosed to inspect all the detail of the app. On this app, no file reading is performed while playback. AIFF, WAV and FLAC is played using the same playback thread code: get raw PCM from memory buffer and put it onto WASAPI buffer using memcpy() It seems some audiophiles in Japan were convinced that lossless FLAC and WAV / AIFF sound can be identical.
  5. Keep original AIFF data on backup HDD and convert it to WAV, FLAC or other formats. Both AIFF and WAV have similar structure, consists of header part and raw PCM data part. Raw PCM data part has the same size but header part is different. Metadata container format is clearly defined in AIFF and FLAC but not standardized in WAV therefore some metadata may be lost in conversion to WAV. File size difference between AIFF and WAV Typical WAV header part is 44 bytes and typical AIFF header part is 72 bytes. (without ID3 tag) Therefore file size may become smaller by approx. 28 bytes on AIFF to WAV conversion. AIFF to FLAC conversion AIFF to FLAC conversion is safer option, metadata should be retained on this conversion. Original uncompressed PCM, identical bit-by-bit to original PCM data, should be recovered from FLAC file and file size becomes smaller than AIFF or WAV when PCM data has some redundancy (repeats or some statistical predictability). If original PCM data has no statistical predictability, FLAC encoder gives up to use compression algorithm and store PCM data as-is and file size becomes slightly larger than AIFF. If AIFF contains 32bit PCM (rare), PCM bit depth may be converted to 24bit on AIFF to FLAC conversion. About lossless data compression Lossless data compression may reduce file size while it retains all the information to recover original data. I'd like to explain how this is possible with RLE compression because it is simple (This method is used in some facsimile but not used in FLAC) When original data sequence is: AAAAABBBBBBBBBAAA It can be expressed and stored as RLE compressed form: {A,5},{B,9},{A,3} Latter form is smaller size while it has all the information of original data. and original data sequence should be restored from lossless compressed data. About FLAC uncompressed This compressed form becomes larger size than original data when original data has no repeat. FLAC encoder tries a few different compression algorithms and if all the compression algorithms produce larger data than original, store the portion of PCM as uncompressed original data as-is. This feature exists in many lossless compression file format. Some FLAC encoders use this feature to create FLAC file of all the PCM stored as an uncompressed form, even when compression algorithm produces smaller data sequence than original data sequence. IMO this is waste of storage space.
  6. Tommy and me: 55.0Hz (A1) Skip the moon: 41.2Hz (E1) Call to rhythm: difficult, 25 to 30Hz ?
  7. Apogee Duet (newer model, old Duet 2 does not support Windows) RME Babyface Pro FS may meet most of your needs. If you'd like to receive Skype phone call while practicing MIDI piano with ASIO synthesizer, I recommend RME On 6/18/2020 at 9:35 AM, john61ct said: It is called `ducking' and this functionality is provided by OS, it should work on all audio devices: https://docs.microsoft.com/en-us/windows/win32/coreaudio/stream-attenuation
  8. WAV file has the start and the end (Unlike digital radio broadcast stream where there is no start and no end) and WAV file format use it as the means to organize data. Offset is the count of bytes from start of the file and it usually counts from zero. On the HxD Editor screenshot of my previous post, 8-digit hexadecimal offset number is added by HxD Editor for human reading convenience. Actual WAV files do not contain offset values in the file, but it can be calculated by counting data bytes from the file start. On the accompanying table of the slides has also offset columns and I added it for readers to compare easily the table rows with HxD screenshot hexadecimal dump. Actual WAV file data is something like this (expressed as hexadecimal number sequences, which is shown in HxD Editor screen) : 52494646AC580100574156... One 1-digit hexadecimal number is actually 4-bit data and it can be expressed as a 4-digit binary number: hex 0 ⇔ bin 0000, hex 1 ⇔ bin 0001, hex 2 ⇔ bin 0010, hex 3 ⇔ bin 0011 hex 4 ⇔ bin 0100, hex 5 ⇔ bin 0101, hex 6 ⇔ bin 0110, hex 7 ⇔ bin 0111 hex 8 ⇔ bin 1000, hex 9 ⇔ bin 1001, hex A ⇔ bin 1010, hex B ⇔ bin 1011 hex C ⇔ bin 1100, hex D ⇔ bin 1101, hex E ⇔ bin 1110, hex F ⇔ bin 1111 Therefore this WAV file data also can be expressed as a binary digits sequence: 0101001001001001010001100100011010101100010110000000000100000000010101110100000101010110... On storage media, value 1 may expressed as the hole (of the punched card), magnetized, charged, high resistance values, etc. As you said, on the "Looking into 16bit PCM data part of the WAV file" slide, last PCM data ends with minus number, this is because I tried to explain 16bit integer value can express minus number as well. Actual WAV file goes on. 1kHz 1 second 44100Hz PCM starts from 441 unique sample values and it is repeated 100 times. Please refer my first post of this thread what it is like this 441 sample values are.
  9. I choose WAV file as an example to explain it. WAV file stored 1 second (truncated) 1kHz sine can be created using WaveGene. Generated WAV file can be read using any Hex editor. I'm using HxD. Click the following images to magnify
  10. There is actually infinite there in the discrete-time sampled 1kHz sine signal: Most of sample values are irrational numbers. This means, to represent one sample value exactly (for example sample#148 = sqrt(3)/2 ), infinite number of digits are needed. 16bit quantization truncates the value of first 16bit of the number to create finite digit rational number and quantization noise is generated by the truncation. Pure 1kHz signal is, by definition, has infinite length. If it is truncated to finite length (1 second), other frequency components appear on the truncated edge and signal is contaminated. You may hear click noise at the truncated edge.
  11. When 1 second of 1kHz signal is sampled by 44100Hz, 44100 sampled values is produced. (This is obvious🙂 ) When we look closer to those 44100 samples, first 441 sample values are repeated 100 times. This is caused by periodicity of sine function : sin(x + 2π) = sin(x). This 441 samples contain exact 10 cycles of sine wave. Most of sampled values are irrational numbers. When those values are quantized to 16bit or 24bit integer PCM, sample values becomes something like the following table. In digital domain, PCM signal is stored/transferred as a list of those integer values. One second of PCM consists of 44100 integer values. First part of the sampled values plotted using Audacity: DAC output analog waveform simulated by Adobe Audition:
  12. Highest performance 75Ω BNC cable currently available is 12G-SDI cable I think. It is engineered for 4K60p video transmission. Way overkill but it can be used for audio
  13. There is a Harman's How to listen app to train listening ability to hear the sound difference.
  14. This article in 2016 says: Aluminium conductor overhead high-voltage cabling is already common (to reduce cable weight). Now power companies start to replace old copper distribution cabling with aluminium to save money. https://www.reuters.com/article/us-aluminium-copper-substitution/auto-power-firms-save-millions-swapping-copper-for-aluminum-idUSKCN0WH1RI
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