<p>While MFCCs have indeed been used in music information retrieval research (for genre classification etc...), in this case (pitch detection) you may want to use  a semi-tone filterbank or constant Q transform as a first information reduction step. These transformations match better with musical pitch.</p>

<p>But I think it's also worth trying to use the audio samples directly with RNNs, in case you have a huge number of samples. In theory, the RNNs should be able to learn the wave patterns corresponding to particular pitches.</p>

<p>From your description, it's not entirely clear what type of "pitch recognition" you're aiming for: monophonic instruments (constant timbre, and only 1 pitch sounding at a time)? polyphonic (constant timbre, but multiple pitches may be sounding simultaneously)? multiple instruments playing together (multiple timbres, multiple pitches)? or even a full mix with both tonal and percussive sounds? The hardness of these use cases roughly increases in the order I mentioned them, so you may want to start with monophonic pitch recognition first.</p>

<p>To obtain the necessary amount of training examples, you could use a physical model or a multi-sampled virtual instrument to generate the audio samples for particular pitches in a controlled way. This way, you can quickly create your training material instead of recording it and labeling it manually. But I would advise you to at least add some background noise (random noise, or very low-level sounds from different recordings) to the created audio samples, or your data may be too artificial and lead to a model that doesn't work well once you want to use it in practice.</p>

<p>Here is a paper that might give you some ideas on the subject:
An End-to-End Neural Network for Polyphonic Piano Music Transcription
(Siddharth Sigtia, Emmanouil Benetos, and Simon Dixon)
<a href="https://arxiv.org/pdf/1508.01774.pdf" rel="nofollow noreferrer">https://arxiv.org/pdf/1508.01774.pdf</a></p>
Which input format is the best for sound recognition in recurrent neural networks?
<p>I want to create sound or pitch recognition with recurrent deep neural network. And I'm wondering with what input will I get best results.</p>

<p>Should I feed DNN with amplitudes or with FFT(Fast Fourier transform) result?</p>

<p>Is there any other format that is known to produce good results and fast learning?</p>