[Speex-dev] Resample UltraWideBand to NarrowBand
Jim Crichton
jim.crichton at comcast.net
Wed Mar 18 08:14:32 PDT 2009
The resampler will convert raw audio from one sample rate to another. You are starting with Speex-encoded audio frames. So, what you need to do is:
1. Run the media frames through the Speex decoder (look at Speexdec or testenc_uwb). This will give you raw audio with a 32 KHz sample rate.
2. Use the resampler to convert the audio from 32 KHz to 8 KHz sample rate.
3. Run the 8KHz audio through a G711 encoder.
For the narrowband case, Asterisk is doing steps 1 and 3.
----- Original Message -----
From: Thiago Maluf
To: speex-dev at xiph.org
Sent: Tuesday, March 17, 2009 4:59 PM
Subject: [Speex-dev] Resample UltraWideBand to NarrowBand
Hi List,
Now I will send to you more specific what I am trying to do.
I have one Asterisk Channel where receives Midia Frames in the codecs format: Speex UltraWideBand and Speex NarrowBand.
When I use Speex NarrowBand the Asterisk is able to convert this frame to G711.
But when I use Speex UltraWideBand the Asterisk don't convert it.
Then I need in my Asterisk Channel Source include the Speex Library in resample this frame in 32KHz to 8KHz.
Searching for it in Speex Doc, I found it:
SpeexResamplerState *resampler;
resampler = speex_resampler_init(nb_channels, input_rate, output_rate, quality, &err);
err = speex_resampler_process_int(resampler, channelID, in, &in_length, out, &out_length);
But in my source I have one *dataframe where is my payload. How I can use it to resample my frame?
Thanks you very much, Thiago.
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