Re: [linux-audio-user] sndfile-info and lots of questions

New Message Reply About this list Date view Thread view Subject view Author view Other groups

Subject: Re: [linux-audio-user] sndfile-info and lots of questions
From: Erik de Castro Lopo (erikd-lad_AT_mega-nerd.com)
Date: Sat Apr 17 2004 - 12:50:40 EEST

On Fri, 16 Apr 2004 09:43:00 -0700 (PDT)
R Parker <rtp405_AT_yahoo.com> wrote:

> Hi,
>
> As I've gone through my most challanging mastering
> project, I've developed more questions than answers.
>
> There's been reference, on this list, to documentation
> that explains file formats-- I don't recall the
> document title or where to find it. Ultimately, I need
> a resouce that explains things like; the number of
> available samples for the different bit depths (16bit
> range from -ABC to +XYZ, 24bit...), DC offset is, peak
> amplitude is, RMS is, etc.

Bits Range DC offset
-----------------------------------------
16 [-32768, +32767] 0
24 [-8388608, +8388607] 0

> I need to know if samples are syncronous with decibel
> level,

Que? I think you men synonymous rather than synchronous.

> is maximum samples equal to 0db?

Yes, it is usually the case that 0dB is simply the maximum
sample value.

> In the following sndfile-info report, what are Length

File length in bytes.

> and Block Align?

An internal detail of how data is stored in a WAV file. In other
words, something you should ignore.

> Version : libsndfile-1.0.6
>
> ========================================
> File : guajira-jam.wav
> Length : 30396228
> RIFF : 30396220
> WAVE
> fmt : 16
> Format : 0x1 => WAVE_FORMAT_PCM
> Channels : 2
> Sample Rate : 44100
> Block Align : 4
> Bit Width : 16
> Bytes/sec : 176400
> data : 30396184
> End
>
> ----------------------------------------
> Sample Rate : 44100
> Frames : 7599046
> Channels : 2
> Format : 0x00010002
> Sections : 1
> Seekable : TRUE
> Duration : 00:02:52.313
> Signal Max : 25922
>
> Is Signal Max a measurement of used samples?

No it is the maximum absoulute sample value. Since this is a
16 bit PCM file, the range of sample values is [-32768, +32767].

What I'll do is change that last line to:

    Signal max : 25922 (-2.04dB)

Erik 

-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam_AT_mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"In civilian equipment, such as computers, the number
of components alone makes miniaturization essential if
the computer is to be housed in a reasonable-sized
building." Electronics Oct. 1, 1957, p. 178

New Message Reply About this list Date view Thread view Subject view Author view Other groups

This archive was generated by hypermail 2b28 : Sat Apr 17 2004 - 18:14:51 EEST