alsa-plugin-ffmpeg (ffmpeg plugins for ALSA) These are the a52 and lavcrate plugins for ALSA. The a52 plugin converts S16 linear format to an A52 compressed stream and sends it to an SPDIF output. The lavcrate plugin is an external rate converter using libavcodec's resampler, which may produce higher quality results than the libsamplerate converter included in Slackware's alsa-plugins package. These plugins are included in the alsa-plugins source, but are not included in Slackware's alsa-plugins package because Slackware doesn't ship with ffmpeg.