Noise Filtering

[puneetchd]

How shall i proceed with Noise filtering from the Audio using NVDSP.
Please show me some way to achieve that. Also i want to recognise a sound pattern in the recorder audio and remove it from that audio file.

[haihw]

Hi,
I have a same question, please tell me and @puneetchd
Can I archive the NSData output from the filter ?
Thanks

[bartolsthoorn]

@puneetchd You copied the NVDSP repo and published as your own instead of just forking it (using the fork button at the top right). This takes away all the credit for my work and is not how Github works.

@haihw You pass an array of floats to the filter. The filter modifies the array itself.

I found this page very clear about how to go about noise cancellation: http://wiki.audacityteam.org/wiki/How_Noise_Removal_Works

It basically relies on converting the data using a FFT algorithm, taking away background noise, for example all frequency bands under a threshold, and putting the data array back together with a reverse FFT algorithm. If you have the FFT and reverse FFT working you can basically come up with your own 'noise' definition and apply your fix. Noise is probably something that is really divided over a lot of frequencies and at a lower level than the actual sound.

Right now NVDSP does not have a FFT algorithm, although it's definitely at the top of the TODO list. A FFT algorithm would also allow a spectrum graph, also a popular/requested feature.

Unfortunately I don't have time to implement it right now, but I might get back to it. Alternatively you can fork this repo and implement it, I will happily merge it and give you credits for it.

[puneetchd]

@bartolsthoorn Hi Bartoisthroon, I have removed the repo from my profile now. Being a tyro in earlier days i couldn't find the way to add/contribute to the project. Pardon me for that.

Thanks a lot for sharing the Audacity link for noise removal, still mid way into fully implementing the noise cancellation algorithm. Once its completed i will merge it into NVDSP.

[bartolsthoorn]

@puneetchd That is great, good luck! Looking forward to your commits!

[bartolsthoorn]

@puneetchd Just curious, did things work out with the noise removal?

[puneetchd]

@bartolsthoorn Unfortunately the project didn't work out and had to close it
I was able to reduce the frequency of noise up to some extend but it was altering the other float values of audio with that, it was not stable actually.
how about you?