[audio_video_recorder] sample_audio_video_recorder.launch doesn't work when audio_format is mp3 by default

[Kanazawanaoaki]

When I tried to run the audio_video_recorder sample(sample_audio_video_recorder.launch), the video did not save properly.
The other sample pr2_audio_video_recorder.launch worked fine, so I'm trying to figure out the cause. As a conclusion, I think it does not work well if the audio_format is mp3.

[Kanazawanaoaki]

I changed the default auido_format to wave format in #1790.

For additional information, https://github.com/jsk-ros-pkg/jsk_recognition/tree/master/sound_classification#usage says that when dealing with audio device in ROS
By

$ arecord -l
$ pactl list short sources

It is correct to investigate the values of arguments such as device:=hw:1,0 channels:=1 depth:=16 sample_rate:=48000 and pass them as arguments to audio_capture