The issue also appears when resampling from 44100 to 48000Hz, but less often.
It can be best observed when resampling a constant signal. Lets say a file with shorts of value 16384. Then, every several thousand samples a 0 will be present in the output. (and ripples around it). If the value of FFTFIRLEN is decreased to 65536/8, then the 0s are more often in the output signal.

Hi,
I'm a rookie on pcm process, would you please help resolve the issue in your project?
Thanks
Alex
Logs are following:

file name is /mono_short_test.wav
channels is 1
frame size is 2
frame rate is 44100.0
Exception in thread "Thread-0" java.lang.IllegalArgumentException
at java.nio.Buffer.limit(Unknown Source)
at vavi.sound.pcm.resampling.ssrc.SSRC.downsample(SSRC.java:1579)
at vavi.sound.pcm.resampling.ssrc.SSRC.(SSRC.java:2440)
at com.jssrc.resample.JSSRCResampler$1.run(JSSRCResampler.java:66)
at java.lang.Thread.run(Unknown Source)

file name is /stereo_long_test.wav
channels is 2
frame size is 4
frame rate is 44100.0
Exception in thread "Thread-3" java.lang.IllegalArgumentException
at java.nio.Buffer.limit(Unknown Source)
at vavi.sound.pcm.resampling.ssrc.SSRC.upsample(SSRC.java:648)
at vavi.sound.pcm.resampling.ssrc.SSRC.(SSRC.java:2438)
at com.jssrc.resample.JSSRCResampler$1.run(JSSRCResampler.java:66)
at java.lang.Thread.run(Unknown Source)

Now, I use your project to convert sample rate, but cost too much time in some low mobile phone. I try to call JNI to raise up conversion speed. I would appreciate it if you provide me with SRC library download address.

Our microphone data is collected in 16k pcm data. Now I want to convert directly to 48k. What can I do?

Can this library convert a double channel into a single channel?
new SSRC(fis,fos,44100,16000,2,2,1,Integer.MAX_VALUE,0,0,true);

Seventh parameters？
help me， thank you