ALSA buffer xrun ao gravar com ffmpeg

Question

Existe alguma maneira de aumentar o tamanho do buffer ALSA?

Ao executar este comando:

ffmpeg -f alsa -ac 2 -i hw:1 -ar 44100 -b 64k output.mp3

Eu recebo um "xrun de buffer ALSA" antes de meu sistema ser bloqueado

Input #0, alsa, from 'hw:1':
  Duration: N/A, start: 2480.999037, bitrate: N/A
  Stream #0.0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
Output #0, mp3, to 'lastzzz.mp3':
  Metadata:
    TSSE            : Lavf53.21.1
    Stream #0.0: Audio: libmp3lame, 44100 Hz, 2 channels, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
Press ctrl-c to stop encoding
[alsa @ 0x1c04660] ALSA buffer xrun.

Aqui está a minha versão do ALSA:

pi@raspberrypi ~ $ cat /proc/asound/version
 Advanced Linux Sound Architecture Driver Version 1.0.25.

Só para ter certeza:

pi@raspberrypi ~ $ sudo apt-get install alsa
 Reading package lists... Done
 Building dependency tree
 Reading state information... Done
 Note, selecting 'alsa-base' instead of 'alsa'
 alsa-base is already the newest version.
 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.