Speech coding sources: filters

[ligoban]

In the Speech coding source code there is USC_Modes structure defined. This structure has 2 filter on/off flags: high pass filter and post filter. Where can I get more information about this filters (cutoff frequency etc.)? I wish not to read the source very deep.

Thanks.

[Vyacheslav_Baranniko]

USC is a wrapper interface for various speech codecssome of which optionally may dopre- and post- filtering, like for example ITU G729, G723.1codecs.Thesemodes/flags are not USC specific rather a specific flag of the codec underneath and may not be supported by some USC codec.

[ligoban]

Thank you.

The other question: I need to amplify speech frequencies (1 kHz - 3 kHz). Are filters of 729 and 723 vocoders suitable for it? I mean what is the cutoff frequency for vocoders that supports high-pass filtering?

Does the postfiltering operation the same as described in the ITU recomendations?

[ligoban]

Still got no response :(

[Vyacheslav_Baranniko]

The G729high pass filters cutoff =140 Hz for encoder (pre-processing, ITU G.729, 3.1) and 100 Hz for decoder (4.2.5).

G723.1 high pass filtercutoff is small <7 Hz, basicallyDC removal.