Why My PocketSphinx Cannot Load LM Bin from SDCard?

[Capt.Michael]

Hi guys,

I cloned https://github.com/cmusphinx/pocketsphinx-android-demo and it runs correctly on my Android phone. And I build my own language model bin file, place it to asset folder, and load by following code, it works fine!

recognizer.addNgramSearch(CORPUS, new File(assetsDir, "corpus.lm.bin"));

But after I put it to /sdcard, it cannot be loaded succeed any more, there's always an error says

java.lang.RuntimeException: Decoder_setLmFile returned -1
  at edu.cmu.pocketsphinx.PocketSphinxJNI.Decoder_setLmFile(Native Method)
  at edu.cmu.pocketsphinx.Decoder.setLmFile(Decoder.java:172)
  at edu.cmu.pocketsphinx.SpeechRecognizer.addNgramSearch(SpeechRecognizer.java:259)
  at edu.cmu.pocketsphinx.demo.MainActivity.setupRecognizer(MainActivity.java:260)
  ...

Please refer to following code, I try to load it from /storage/emulated/0/corpus.lm.bin, and lmFile is not null. And the second line is line 260 of MainActivity.java.

File lmFile = new File(Environment.getExternalStorageDirectory(), "corpus.lm.bin");
recognizer.addNgramSearch(CORPUS, lmFile);

The only difference is path.

How could I load language model bin file from storage? I have to, because my real language model bin file is too large to put it under asset folder.

Thanks very much in advance!

[Nickolay V. Shmyrev]

You can check errors in logcat for details

[Capt.Michael]

@Nickolay,

I just realized there's a filter remains in logcat, that makes me didn't see some logs, thanks for reminding!

And now, detailed error message is:

04-19 10:53:35.159 15363-15363/edu.cmu.sphinx.pocketsphinx E/cmusphinx: ERROR: "ngram_model_trie.c", line 356: File /storage/emulated/0/corpus.lm.bin not found
04-19 10:53:35.159 15363-15363/edu.cmu.sphinx.pocketsphinx E/cmusphinx: ERROR: "ngram_model_trie.c", line 179: File /storage/emulated/0/corpus.lm.bin not found
04-19 10:53:35.159 15363-15363/edu.cmu.sphinx.pocketsphinx E/cmusphinx: ERROR: "ngram_model_trie.c", line 447: Dump file /storage/emulated/0/corpus.lm.bin not found

I've pushed corpus.lm.bin to /storage/emulated/0/, and I debugged, lmFile is NOT null at line which invokes addNgramSearch() method.

File lmFile = new File(Environment.getExternalStorageDirectory(), "corpus.lm.bin");
if (lmFile.isFile()) {
recognizer.addNgramSearch(CORPUS, lmFile);
}

And of course, I've append READ_EXTERNAL_STORAGE permission to AndroidManifest.xml already.

So, I'm wondering why ngram_model_trie.c cannot get such file?

Thanks a lot!

[Nickolay V. Shmyrev]

Try to open this file from java, maybe permission did not apply somehow.

[Capt.Michael]

Yes, you're right! God damn I forgot I run it on an Android 7.0 phone :(

Thank you so much!