5
votes
Accepted
How to get the volume level from PCM audio data?
There are two separate issues behind your question: the duration of the measurement and the algorithm used to do the actual metering. In the audio jargon, the term used for the perceived level ...
- 316
4
votes
Accepted
Decoding a PCM BFSK signal (Bell 103)
The frequency resolution is independent of the sampling rate. Consider that in the extreme of an infinite sampling rate (continuous time), the Fourier Transform of a single FSK symbol at either 1070 ...
- 55k
3
votes
Accepted
What are the definitions of symbols and samples related to PCM?
Quantization and encoding are largely independent. "Symbols" is another word for "pulses", and the line encoding can also play a role in how the information is transmitted.
Say you quantize one ...
- 15.4k
2
votes
Accepted
Minimum Channel Bandwidth for PCM
I don't think the exam question is stated properly, unless there is additional context that the student is supposed to know.
First, the bandwidth depends on the encoding. The question seems to assume ...
- 15.4k
2
votes
Accepted
Nyquist Maximum data rate formula for PCM
The first document (from mason.gmu.edu) gives a confusing explanation of the formulas. The second document is what's the standard way of referring to the channel capacity
Now the two formulas are:
$...
- 28.4k
2
votes
Accepted
What specifically does PCM refer to?
I like this paper a lot: The philosophy of PCM. It explains PCM very clearly, includes references to some of the earliest papers on it, and you can hardly argue with the qualifications of the authors :...
- 15.4k
2
votes
How to choose PCM Buffer Size?
For this type of application a fairly wide range of buffer sizes should work fine, although the exact details depend on your specific hardware and operating system (if any). 1500 seems like a very ...
- 48.2k
2
votes
Accepted
Software Mixing of Multiple Audio Streams From Network
Generally you will need some sort time sync protocol.
Typically you want create locally one circular buffer for each network channel. As soon as a packet comes in, you shove it into circular buffer ...
- 48.2k
2
votes
Accepted
Remove noise introduced while converting a Delta-Sigma Modulated (DSM) signal into a pulse-code modulated (PCM) signal?
The spectrum appears to be the noise-shaping associated with Delta-Sigma Modulation. Specifically we see that the noise increase follows a 20 dB/decade slope, indicative of a first-order delta-sigma ...
- 55k
1
vote
How to get the original sample pitch knowing how the sample is interpolated at a given pitch?
That's how many other sound chips work, both wavetable and FM synthesizers, from C64 SID to Yamaha FM synthesis and these Ensoniq-type sound cards like Gravis UltraSound which is supposed to base on ...
- 2,331
1
vote
Echo removal from a chunk of PCM signal
Your $S_{new}=N-F$ requires that you know both $N$ and $F$.
But since $N=F*R$, with $*$ being convolution, and $R$ being the Room Impulse Response (RIR), you're solving the equivalent problem $S_{new} ...
- 32.5k
1
vote
What specifically does PCM refer to?
I think it's helpful to derive the literal meaning of PCM.
The process of multiplying two signals is Amplitude Modulation—AM. If one signal is a constant 1, the other passes though. If 0, no signal ...
- 791
1
vote
UART signal recovery from PCM data
This signal looks pretty good, so that a simple sign decision gives you "low" or "high" periods.
Then, you just start at the beginning, and count samples until you find your start ...
- 32.5k
1
vote
Digital Audio Mixing Fundamental. What will be the data rate of mixed audio?
When you add multiple audio sources, you must first make sure that they use the same sampling rate, and then same numerical format, so that addition can be realized.
So, if they are not at the same ...
- 28.4k
1
vote
Accepted
Error reading a .PCM file
That sure looks like your are including the .WAV file header as part of your data.
When you read your file in, and write it out, using the file operations, you are not accounting for the header. The ...
- 7,600
1
vote
Can we band-limit a PCM signal? Is it even relevant to relate a totally Analog term(Band limit) with digital one(PCM)
Yes -- it's just a matter of selecting the right pulse shape.
(By the way, it makes perfect sense to talk about the bandwidth of a PCM signal; it is, after all, a continuous-time physical signal with ...
- 15.4k
1
vote
Accepted
Windows Audio WAVEFORMAT buffer BYTE to 16-bit int
This doesn't seem to be very good code, and it certainly isn't well commented to explain why it is doing what it is doing.
To answer your question at the "***** WHAT'S GOING ON HERE *******" mark:
...
- 7,600
1
vote
How to mix 8bit/8kHz unsigned linear PCM data in AppsScript?
Assuming that abyte[] and bbyte[] are two arrays with samples valued from 0-255, this is the ...
- 201
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