I make a mistake in previous tests (time results contain my interaction) The correct results are:
time avconv -i nfsroot2/bitstreams/720p/Source.Code.2011.BluRay.720p.DTS.x264-CHD.mkv -t 0:1:0 -f s16le a.pcm panda -- 7.005s mx53 -- 53.903s
time avconv -i nfsroot2/bitstreams/720p/Source.Code.2011.BluRay.720p.DTS.x264-CHD.mkv -t 0:1:0 -f s32le b.pcm panda -- 7.862s mx53 -- 60.235s
time avconv -i nfsroot2/bitstreams/720p/Source.Code.2011.BluRay.720p.DTS.x264-CHD.mkv -t 0:1:0 -codec:a copy SourceCode.dts panda -- 1.568s mx53 -- 5.155s
time avconv -i SourceCode.dts -f s16le a.pcm panda -- 6.320s mx53 -- 50.526s