what is a 16 bit linear PCM

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Hi to all
anyone can help me to know hat is 16 bit linear pcm?

From the OP: "I want to know about it from implementation point of view. I mean, how I can convert a singnal to 16 bit linear pcm? Is there any source code or example out?"

Posted 12-May-11 4:37am

AmirAlilou

Updated 12-May-11 4:53am

Marc A. Brown

v2

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4 solutions

Solution 1

Read all about it here: http://wiki.multimedia.cx/index.php?title=PCM[^].

Did you even try to google that?

Cheers!

-MRB

Posted 12-May-11 4:41am

Manfred Rudolf Bihy

Comments

AmirAlilou 12-May-11 10:59am

hi manfred,
i need to know implementation details.ho i can convert captured audio to 16bit LPCM?
is there any sample or source code or algorithm?

best wishes

Albert Holguin 12-May-11 13:19pm

if you captured the audio with a 16bit A/D (from a soundcard or digitizer), then its already 16-bit linear PCM, see my solution

Solution 2

Google[^] is your friend. First result.[^]
Bing[^] is also your friend. The first result from google is also the first result from bing.

Posted 12-May-11 4:42am

Marc A. Brown

Updated 12-May-11 4:43am

v2

Solution 3

PCM stands for Pulse Code Modulation, and Wiki [^]explains it better than I ever could (it uses pictures, which really helps)

The 16-bit part just tells you the range of values you can get 0 to hex FFFF in this case for 16 bits.

Posted 12-May-11 4:42am

OriginalGriff

Comments

Albert Holguin 12-May-11 13:26pm

PCM's not that hard to understand or explain (specially when linear), 3 steps:
1. Sample,
2. Quantize,
3. Encode

OriginalGriff 12-May-11 14:43pm

I know - but if you need to ask the question, you need a picture to understand the point! :laugh:

Albert Holguin 12-May-11 16:33pm

btw, the 16bit tells you the number of possible values, not exactly the range, since it can be signed or unsigned

OriginalGriff 13-May-11 3:22am

Depends on the ADC, but yes.
I used to love CD players, which proudly boasted on the front "One bit DtoA converter!"

Albert Holguin 13-May-11 10:11am

usually one bit implies a differential algorithm is used, still a lot of modern systems use low bit resolution for a lot of applications, GSM only uses 3bits

Albert Holguin 12-May-11 16:35pm

Here's a picture for ya!
Picture[^]

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Albert Holguin · Accepted Answer · 2011-05-12T05:01:00

What does your signal start off as? If you do standard sampling with a 16-bit A/D (and quantize linearly, which is what most A/D's do already), you have 16-bit linear PCM. If you're talking about converting between types, then that's a different story.

Non-linear, or compressed, algorithms effectively add a larger number of quantization states for voltage levels that are of interest (typically the lower values), thereby adding fidelity to lower levels and compressing the large levels to a smaller number of states. (this includes u-law and A-law)

Differential, or delta, algorithms effectively encode the differences in voltage levels instead of the voltage level itself. They are commonly used for providing decent audio with lower bit rates. (includes DPCM)