I am looping the "PCM audio in" to the "PCM audio out" on a Sound Blaster USB card using the following command:

arecord -q -f S16_LE -r 48000 -c 2 -D dsnoop:HD | aplay -q -D plughw:HD

It works fine, but only for about three hours. The command is in a while loop which restarts it when it stops and also records the time at which the command is restarted. It has run for the following lengths of time:

h m s





About 11,187 seconds, give or take. These seem too similar to be the result of a random fault. The man pages for aplay and a record say that a duration of 0 means infinity.

Any suggestions as to why it stops reliably after 3hr 6min and 27seconds?


.wav files have a 2 GB size limit.

Use -t raw instead:

arecord -q -f dat -t raw -D dsnoop:HD | aplay -q -f dat -t raw -D plughw:HD
| improve this answer | |
  • That fixed it. Its been going for over 5 hours now. Although 11187 sec * 48000 s/sec * 2 channels * 2 bytes/sample = 2.147 MB so out by 2 somewhere. On re-reading the man page perhaps --max-file-time may also have worked. Well spotted, many thanks. – Ian Davidson Aug 23 '18 at 1:49

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