[linux-audio-user] extract and mix

[Mark Knecht]

On 12/19/05, Brad Fuller <brad at sonaural.com> wrote:
> Brad Fuller wrote:
>
> > Brad Fuller wrote:
> >
> >> I couldn't find a way to do this in ecasound, maybe there's a way to
> >> do it. Here's what I want to do:
> >>
> >> Find the exact length of a audio file in ms. I think ecalength can do
> >> this, I know it's not sample accurate, but I just need down to the
> >> around 1ms. Maybe there's another option other than ecalength.

sndfile-info?

mark at lightning ~ $ sndfile-info Web-music/2AM-40Bars.wav

Version : libsndfile-1.0.11

========================================
File : Web-music/2AM-40Bars.wav
Length : 35744300
RIFF : 35744292
WAVE
fmt  : 16
  Format        : 0x1 => WAVE_FORMAT_PCM
  Channels      : 2
  Sample Rate   : 44100
  Block Align   : 6
  Bit Width     : 24
  Bytes/sec     : 264600
data : 35744256
End

----------------------------------------
Sample Rate : 44100
Frames      : 5957376
Channels    : 2
Format      : 0x00010003
Sections    : 1
Seekable    : TRUE
Duration    : 00:02:15.087
Signal Max  : 7.50863e+06 (-0.96 dB)

mark at lightning ~ $

I cannot help with the rest. Sorry.

- Mark
> >>
> >> Then, I want to extract a section of another file: at a specific
> >> location in ms at a length of the file above.
> >>
> >> Then, mix that extracted segment with another file and save the
> >> result to a new file.  How can this be done? I don't know of a
> >> utility that can extract a specific length at a specific location in ms.
> >>
> >> brad
> >>
> >>
> > I forgot all about sox - looks like I could use sox to essentially
> > extract a section by using the feature "trim start length"
>
> does anyone have any ideas on how I can accomplish this process? Has
> anyone used the "trim" feature in sox?
> Also, I like to be able to extract the file section (step 2 above) to
> the nearest zero crossing (to prevent potential clicks). Any pointers,
> even off the top of your head, would be most appreciated.
>
> thanks,
> brad <http://www.oreillynet.com/pub/au/2184>
>