Slow MP3 decoding

[reminmax]

Hello Yang.
Thanks a lot for the code.

MP3 decoding is very slow (a 300 sec file takes more than 20 seconds to decode). Wav decoding is twice as fast.
Is there any way to speed up this process?

I've found reports that MediaCodec itself is slow, but I'm not sure. The technical messages were about earlier versions of Android.

[stefanJi]

Recommend use ffmpeg decoding mp3 to wav data, and use this code generates waveform from wav data.

[dprevost-LMI]

Hey, I stumbled into the same problem with an MP3 file. I just found this page explaining how to boost the buffer's reading. I tried, but the waveform is different now after accumulating the input buffer.

Since the perSamplePoints is calculated from the sampleRate, the duration, and the expectPoints, I was not expecting that reading the input buffer faster would alter the waveform, but it did.

I observed that the output buffer's bytes changed drastically after reading the input buffer faster.

Example: For a ~700Kb mp3 file, the input buffer read was 715 Kb in both cases, but when reading a single buffer at a time, the output reached 7236 Kb, while if read with a 0.5 Mb buffer accumulating the data, the output was only 432 Kb.

Since the output buffer size is much smaller, the optimized version reaches the perSamplePoints in the RMS only once.
Do you have any hint on what I should do to fix this? Thanks!