Speech codec

[Jason123]

Hi,

Could you please add Celp. Code excited linear prediction or maybe even speex to audacity please thanks for making audacity really enjoy using it great audio editor.

[steve]

Speex files can be exported by selecting an external encoder in the Export dialog: http://manual.audacityteam.org/o/man/ex ... ogram.html
I've not tried Celp, but I presume that can too.

+1 for adding Speex as a built-in export option.
No comment on Celp as I've never used it and know little about it.

[Jason123]

Ok thanks Steve if you do decide to add them look forward to using them.

[Trebor]

If you install ffmpeg into Audacity you get the option of using telephone codecs like AMR

how to download and install ffmpeg libraries. ... http://manual.audacityteam.org/o/man/fa ... tml#ffdown .

AMR is a hybrid speech coder, and as such transmits both speech parameters and a waveform signal
Linear predictive coding (LPC) is used to synthesize the speech from a residual waveform. The LPC parameters are encoded as Line spectral pairs (LSP).
The residual waveform is coded using Algebraic Code Excited Linear Prediction (ACELP).

http://en.wikipedia.org/wiki/Adaptive_M ... c#Features

[Jason123]

Hi trebor,

Yes i use amr nb and read it is a acelp but celp is a little but different maybe just a little bit better thanks for the reply.

[Gale Andrews]

Yes i use amr nb and read it is a acelp but celp is a little but different maybe just a little bit better thanks for the reply.

Audacity 2.0.6 for Windows and Mac when released in the coming week or so will support Speex export without using the (external program) command-line exporter. You will need to install the FFmpeg 2.2.2 version that will be recommended for 2.0.6, then choose "Custom FFmpeg Export" in the Export Audio dialog and choose "Speex" format and "libspeex" codec.

The lists in Custom FFmpeg Export are buggy but look in the "Format" line near the top to see what format and codec is chosen. Add ".spx" extension (without quotes) to the end of the exported file name and export at 8000 Hz, 16000 Hz or 32000 Hz project rate.

Xiph.Org regards Speex as deprecated and recommends the higher quality Opus codec instead. You can export Opus in a similar way using Custom FFmpeg Export. It's possible we may offer built-in Opus export at some future time. I doubt we will build in Speex export now it is deprecated.

CELP is a family of encoding algorithms rather than one. Most are heavily patented. You may have to purchase an encoder (software or hardware) if you insist on using CELP.


Gale

[waxcylinder]

I'm confused - does this need transferring to Wiki>PFR?

[steve]

As Gale wrote, the Speex format is deprecated and has been superseded by the Opus format.
Adding support for Opus to Audacity is already on the FR page, and I have added my vote for it.

As Jason123 voted for Speex before Gale pointed out that it had been superseded, I guess that his vote could be added to the request for Opus support.

As Gale pointed out, most of the Celp family of codec are heavily patented, so are likely to fall under "things that we can't implement", in which case there is probably no point in counting a vote for that.

[Gale Andrews]

As Gale wrote, the Speex format is deprecated and has been superseded by the Opus format.
Adding support for Opus to Audacity is already on the FR page, and I have added my vote for it.

As Jason123 voted for Speex before Gale pointed out that it had been superseded, I guess that his vote could be added to the request for Opus support.

OK I did that and archived this topic.

You can export Opus in a similar way using Custom FFmpeg Export.

That seems to be no longer true as of Audacity 2.0.6, but you can still export to opus using "(external program)". See http://forum.audacityteam.org/viewtopic ... 56#p268956.


Gale