Hydrogenaudio Forums

Lossy Audio Compression => Speech Codecs => Topic started by: sean darcy on 2015-02-16 17:59:54

Title: amr-wb : higher bit rate helps in noisy conditions ?
Post by: sean darcy on 2015-02-16 17:59:54
I'm playing with using amr-wb for podcast recordings on my android.  I'm really size constrained, and it seems amr-wb does a better job than opus in the 12 kbps range.  But the same as opus ~ 16 kbps. See:

http://research.nokia.com/files/public/%5B..._Opus_Codec.pdf (http://research.nokia.com/files/public/%5B16%5D_InterSpeech2011_Voice_Quality_Characterization_of_IETF_Opus_Codec.pdf)

I'll be using this over the car radio, so a relatively noisy environment.

The Library of Congress uses amr-wb for some of its sound recordings. In its description of the codec:

The available bitrates are: 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85 kbps. The lowest rate that provides excellent speech quality in a clean environtment is 12.65 kbps. Higher rates are useful in background noise conditions......

http://www.digitalpreservation.gov/formats...fdd000255.shtml (http://www.digitalpreservation.gov/formats/fdd/fdd000255.shtml)

Now if I need to go up to the 16 kbps range, I might as well use opus, which I use for all my music. But does it make sense that a higher bitrate makes any difference in noisy conditions ?? If I have excellent speech quality at a low noise level, don't I have excellent speech quality at a high noise level? I may need to increase the volume to compete with the noise, but the speech quality hasn't changed. And a higher bitrate doesn't increase the volume. Correct?

Title: amr-wb : higher bit rate helps in noisy conditions ?
Post by: saratoga on 2015-02-16 18:50:07
That refers to the noise of the recording, not the noise of the playback environment.
Title: amr-wb : higher bit rate helps in noisy conditions ?
Post by: sean darcy on 2015-02-16 19:10:24
Ah. So if I'm transcoding, then 12.65 kbps will work? Great.

Thanks
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