I work with FRDM-K64F in CodeWarrior and KDS+KSDK. One part of my big project is a player WAV, MP3 and (may be) AAC and FLAC files.
Without any problem I make a WAV player (play files from USB stick and FLASH memory) based of example for SDK and MQX, it work finely in baremetal (KDS project) and with MQX (CW project).I get clear sound from external DAC (CS4350 from Cirrus logic) via I2S.
But I have a problem with software MP3 decoder.
I try to ported HELIX MP3 decoder from some projects for STM32. Decoder work (I try to use ASM and C realisations of Polyphase filter),
but in all variants sound have a DISTORTION!
The sound is very similar to roar (or crackles), or like a "overload" of the analog signal. This "roar" is heard only in the moments of the signal, during playback of silence at the beginning and end of the file there are no distortions.
I try to use example for Kinetis K-40, but get same distortions.
Can anyone share your implementation of software MP3 decoder for Kinetis?
Thank you for any help!