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Questions tagged [pcm]

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Converting 8-bit to 16-bit LPCM: multiply by 256 or 257?

I am converting 8-bit LPCM audio to 16-bit in software and, in order to cover the full 0–65535 destination range with my 0–255 source range, I multiply the samples by 65535/255, which is exactly 257. ...
sam hocevar's user avatar
1 vote
1 answer
80 views

How to get the original sample pitch knowing how the sample is interpolated at a given pitch?

I'm trying to "reverse engineering" a sample-based synth from the 90's (an Ensoniq SQ1, which uses a OTIS chip for the samples; if you're interested you can find the manual of both on the ...
Parduz's user avatar
  • 111
0 votes
0 answers
96 views

For PCM audio samples, can values like max RMS and frequency magnitude be estimated?

I am using OpenAL and a loopback driver to grab PCM samples of whatever audio is being played on the computer in realtime. The PCM data is 1024 samples of 16 bytes (C# ...
McGuireV10's user avatar
1 vote
1 answer
358 views

How to choose PCM Buffer Size?

I am new to MEMS digital microphone world. Currently, we are using built in PDM to PCM converter available in microcontroller. The problem that is troubling me is how to choose the PCM buffer size, ...
Tom's user avatar
  • 11
3 votes
0 answers
279 views

A problem about SQNR, PCM, DPCM, and DM

A baseband analog message signal $x(t)$ with bandwidth 20 kHz, power $10^{-3}$, and $|x(t)| \leq 1$ is waveform encoded and transmitted through a channel of bandwidth 160 kHz. Besides, let the sampled ...
Wei-Cheng Liu's user avatar
0 votes
0 answers
27 views

How to convert non-standard sample range to standard

I'm working on a project to record sound from a Raspberry Pi. I have ADC values ranging from 0 to 4095. I can convert it to an audio file and hear my voice. 12-bit ADC resolution with a sample rate of ...
Jason's user avatar
  • 1
0 votes
0 answers
36 views

with PCM-16 no speech sound

I am trying to create a synthethic speech dataset. A quick overview of the my process is: read wav apply stft do some stuff (ex. add noise, etc.) apply istft write wav Now, the .wav file that I am ...
Kadir Gunel's user avatar
2 votes
0 answers
103 views

Adaptive Delta Modulation: Logic for step size control at receiver

I read that in adaptive delta modulation, we have a block for step size control (diagram below) which takes into account the one bit quantizer output in a feedback loop and modulates it, the intent ...
Curiosity's user avatar
  • 367
1 vote
1 answer
146 views

Question on PCM Sampling and Quantization order

I had a doubt in my mind regarding the orders of sampling and quantization in PCM. What is the impact if the order is reversed, that is, the continuous time signal is first quantized and then sampled? ...
Curiosity's user avatar
  • 367
2 votes
1 answer
204 views

Software Mixing of Multiple Audio Streams From Network

TLDR: How do I mix network streams when streams might be unreliable? I am working on a project which will allow musicians to practice/perform together over the internet with low latency. (Think ...
Jacob Blomquist's user avatar
1 vote
1 answer
239 views

Remove noise introduced while converting a Delta-Sigma Modulated (DSM) signal into a pulse-code modulated (PCM) signal?

I'm writing a tool that converts a dsdiff audio file (dsd64) into a flac audio file (DSM -> PCM). The project is both a programming exercise and a signal processing exercise; I'm learning a lot ...
FirefoxMetzger's user avatar
1 vote
1 answer
130 views

Echo removal from a chunk of PCM signal

I have implemented a paper regarding echo detection in real-time using MFCC coefficients. Now, I want to remove the echo from the mixed signal. Let me explain it as: There are two signals, NearEnd ...
Khubaib Ahmad's user avatar
0 votes
2 answers
92 views

What specifically does PCM refer to?

What specifically is PCM? I've seen it refer to: the sampling and quantisation of an analogue domain signal into digital samples those sample quantisations alone in the digital domain i.e. in memory ...
Lewis Kelsey's user avatar
0 votes
1 answer
92 views

UART signal recovery from PCM data

I have a PCM signal recording of UART data after high-pass filter. The recording looks like this: I know baud rate and parity setting beforehand. What algorithm could help me recover actual binary ...
thesame's user avatar
0 votes
0 answers
1k views

How to scale audio signal from PCM data to a dB SPL value?

I've got a set with MEMS microphones that measure audio signals at ultrasonic frequencies. The MEMS microphones have a PDM output which is then converted into PCM (this is necessary to allow for a ...
dg1271's user avatar
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0 votes
1 answer
618 views

What is causing these spikes in the output of the low pass filter?

I am low pass filtering the PCM of an arbitrary Bell 103 (300 bps) signal. However, the output of the low pass filter shows random spikes in amplitude. I have tried to increase the bandwidth, but no ...
LearningDSP's user avatar
0 votes
1 answer
117 views

Carrier frequency offset in Bell 103 FSK system

This question is a sequel of the discussion that started in this question. Dan Boschen suggested some very nice solutions to decode a Bell 103 FSK signal. I am especially interested in decoding the ...
LearningDSP's user avatar
0 votes
1 answer
987 views

Decoding a PCM BFSK signal (Bell 103)

A recent project requires me to get into some basic DSP, in C. I receive PCM samples of a BFSK signal (Bell 103). The sample rate is 8 kHz. The mark and space frequencies are 1070 and 1270 Hz. To ...
LearningDSP's user avatar
-1 votes
1 answer
1k views

Analyze PCM data

I am getting some 16 bit PCM data (raw bits) from a serial port . I need to collect this stream of bits using some python application running in PC and store it somewhere(Assume it in an array). I ...
Vishnu CS's user avatar
1 vote
1 answer
73 views

Digital Audio Mixing Fundamental. What will be the data rate of mixed audio?

I have voice data at 128 kbps coming from three different sources. I'm looking for mixing all three voices together and sending it back to speakers. What methodologies are there for mixing digital ...
hctrivedi3's user avatar
0 votes
1 answer
140 views

What are the definitions of symbols and samples related to PCM?

What are the definitions of symbols and samples related to PCM? For example in binary encoding $\{0,1\}$ with 8 levels of quantization, is one symbol either of $ \ 0 \ or \ 1\ $? or is it the ...
helloworld1e.'s user avatar
2 votes
1 answer
4k views

Nyquist Maximum data rate formula for PCM

The Nyquist maximum data rate formula for a binary PCM is given by $$C = 2B\log_2L$$ I'm not very sure what "$B$" is here. Is it the bandwidth of the signal being sampled or is it the channel ...
Navin's user avatar
  • 35
0 votes
0 answers
90 views

Number of binary digits in PCM

This is the problem from Shaum Otlines Analog and Digital Communications, Hwei Hsu Problem 5.13. It asks for number of binary digits in each sample if each sample at the receiving end of the system ...
cdummie's user avatar
  • 197
0 votes
1 answer
353 views

Error reading a .PCM file

I want to convert a .wav file with a sampling frequency of 44100 Hz to a 16 depth .pcm. I don't why I'm getting those peaks at the beginning of .pcm plot (second figure below 2). If you could ...
Pereira da Silva's user avatar
0 votes
1 answer
83 views

Can we band-limit a PCM signal? Is it even relevant to relate a totally Analog term(Band limit) with digital one(PCM)

Can we band-limit a PCM signal?
yamini tellam's user avatar
1 vote
2 answers
4k views

Minimum Channel Bandwidth for PCM

Please check if my answer to GATE IN 2010 question 11.20 is correct/can be improved upon. So, every $\frac{1}{f_s}$ sec, a sample is taken. The signal amplitude is quantized into $2^n$ levels such ...
Aditya P's user avatar
  • 171
0 votes
1 answer
383 views

Windows Audio WAVEFORMAT buffer BYTE to 16-bit int

I am trying to understand audio-buffer processing at the low-level for the first time. I have the following C++ code copying WAVE-format byte data from capture buffer of Window Core Audio (*ppData in ...
blisstdev's user avatar
  • 103
6 votes
1 answer
13k views

How to get the volume level from PCM audio data?

I have a decoded PCM audio data obtained from the Web Audio API. I'd like to generate a chart that represents the volume level (perceived by humans) over time. ...
Misha Moroshko's user avatar
0 votes
1 answer
4k views

why companding is used?

Which one is the best answer? Companding is used [] ...
Bibek Ghimire's user avatar
2 votes
2 answers
1k views

How to mix 8bit/8kHz unsigned linear PCM data in AppsScript?

I am having the most difficult time mixing simple unsigned 8-bit/8kHz linear PCM audio samples in JavaScript (AppsScript). I've tried all the basic maths listed here, employing basic number arrays. ...
Jé Queue's user avatar
  • 121
0 votes
1 answer
986 views

How is a PCM byte converted to a voltage level?

16-bit signed PCM would have possible values of ~-32,000 to ~+32,000. How is this value converted to a voltage level for the speaker? If a DAC outputs 5VAC, the values would be ~+-5v. How is the ...
Kunal Chopra's user avatar