Hi, I have been recently trying to record bat ultrasound with Audiomoths v1.2.0 with firmware 1.8.1 installed. In recording sessions scheduled for two nights (i.e. starting at 19:35 and ending at 6:15 next morning) I got long periods with files recorded without the RIFF head (so, they are unreadable and I cannot expand them with the configuration app) with some sporadic files with erroneous RIFF chunk size, which I cannot expand with the app, but have data that I can visualize in a WAV editor, and then periods when the audio files where correctly recorded and could be read. For example, one night I got this list of erroneous files:
20230614_193500T.WAV - RIFF chunk size does not match file size.
20230614_193516T.WAV - Could not find RIFF chunk ID.
20230614_193532T.WAV - Could not find RIFF chunk ID.
...... some 790 more erroneous files until
20230614_230036T.WAV - Could not find RIFF chunk ID.
20230614_230020T.WAV - Could not find RIFF chunk ID.
20230614_230004T.WAV - Could not find RIFF chunk ID.
and then normally recorded files from 23:49 up to 02:33:
20230614_234908T.WAV
....
20230615_023308T.WAV
after that, I got a new long period with erroneous files:
20230615_023340T.WAV - Could not find RIFF chunk ID.
20230615_023356T.WAV - Could not find RIFF chunk ID.
.........
20230615_055205T.WAV - Could not find RIFF chunk ID.
20230615_055149T.WAV - Could not find RIFF chunk ID.
Up to the end of the recording schedule at 06:15
And then no good files either recorded until 22:45 next evening (the recording schedule started at 19:35)
20230615_224541.WAV
.... and recorded good files up to the end of the schedule at 6:15
MapAM20_20230616_061445.WAV
So, any idea of what was going on?
The recordings were being done in a desert area in northern Mexico, in mid June, and the temperature was very high (35.3 °C according to the first Audiomoth recording at 19:35). Could the ambient temperature affect the functioning of the Audiomoth?
Thanks for the attention,
Toni Guillén, Instituto de Ecología AC, Xalapa, Veracruz, México
Hi Toni,
Can you confirm what batteries and SD cards you were using? And also share the CONFIG.TXT file from the SD card. Can you also check the reported battery voltage in one of the good files - 20230616_061445.WAV. If you open it in AudioMoth Play (https://play.openacousticdevices.info) you can select 'Show file information' to see this information. Can you also post an example of the erroneous files somewhere so we can look at the headers?
I think the AudioMoth is suffering from SD card write errors. In normal operation, it writes the file and then goes back and updates the header once the recording is complete and it knows the file size. This update does not seem to be happening correctly in the erroneous files. Maybe due to low battery conditions or a problem with the SD card. We have an update coming out for the Config App which will allow you to generate a summary of the files on the SD card which will be useful for debugging cases like this. What operating system do you use? I can send you a test version to use to summarise the SD card.
Alex