Makefile to pre-process downloaded podcasts

process-podcasts-Makefile

# process podcasts

MP3S = $(filter-out $(wildcard *.64kbit.mp3),$(wildcard *.mp3))
PROCESSED = $(patsubst %.mp3,%.64kbit.mp3,$(MP3S))

.PHONY: process
process: videos $(PROCESSED)
	@echo Done.

.PHONY: videos
videos: $(wildcard *.mp4)
	@if [ -n "$^" ]; then \
		echo Moving $^. ; \
		mv $^ video/ABC/ ; \
	fi

%.64kbit.mp3: %.mp3
	@echo Processing $^
	@nice sox --no-show-progress --multi-threaded \
		--buffer 32768 --norm "$<" "$@" \
		tempo -s 1.33 channels 1 rate 22050

	@# strip id3 tags so player puts all podcasts in the same folder
	@id3v2 -D $@ > /dev/null

	@mv $< reencode/original/
	@echo Done $^

The goal is to:
a) reduce filesize of podcasts (192kbit/s is overkill for spoken word!)
b) normalize the volume and convert to mono (easier to listen to when riding/running and it's windy)
c) speed up playback (people talk too slow!)
d) strip tags (so my dinky mp3 player doesn't put the podcasts into different "folders")

Prerequisites:

• sox
• id3v2