Audio on Andrew's Memory Blog

Shrinking files on AntennaPod

andrewmemoryblog@gmail.com (Andrew's Memory Blog) — Fri, 12 Sep 2025 22:32:08 -0700

I like to listen to podcasts, and my favourite podcast app for Android is AntennaPod. I like the control it gives me, the fact that it deals reasonably with non-audio RSS feeds, the wide range of speed controls, and the searchability.

But I download a lot of podcasts. That means there’s a lot of stuff ready for me when I go on flights and things like that, but otherwise it’s, you know, waiting. Some podcast feeds think I want really high quality audio. Like 256 or 320 k/second. Nope, don’t need that.

Finally I figured out that it might be smart to recode some of the podcasts to free up space on my chronically overfilled phone. That’s what I did. Here’s how I did it. First, you have to be in developer mode and be able to connect over adb. Then:

adb shell "ls /storage/emulated/0/Android/data/de.danoeh.antennapod.debug/files/media/"
adb pull "/storage/emulated/0/Android/data/de.danoeh.antennapod.debug/files/media/your-podcast-directory-name"
cd your-podcast-directory-name
mkdir recoded
for i in *.mp3; do echo $i; lame -V6 "$i" "recoded/$i"; done
cd recoded
for i in *.mp3; do echo $i; adb push "$i" "/storage/emulated/0/Android/data/de.danoeh.antennapod.debug/files/media/your-podcast-directory-name/$i"; done

(Replace your-podcast-directory-name with something that exists. Oh, and I’m running the debug version ‘cause I build it from source… you’ll probably just want de.danoeh.antennapod instad of de.danoeh.antennapod.debug.)

By doing this on my two fattest podcast directories, I was able to save 4+ G. Nice!

Setting up soundmodem on Ubuntu 10.04

andrewmemoryblog@gmail.com (Andrew's Memory Blog) — Wed, 29 Jun 2011 22:23:42 -0700

After a long delay, I finally decided to upgrade to 10.04 LTS and get soundmodem running again.

Luckily, there was help this time. I started with my config, and merged with this post: ubuntuforums.org/showthread.php?p=10864691

Here’s the config I ended up using:

Configuration: AX.25 IO: Mode: soundcard Audio Driver: /dev/dsp Half Duplex: selected PTT Driver: none

Channel Access: TxDelay: 150 Slot Time: 100 P-Persistence: 40 Full Duplex: not selected TxTail: 10

Channel 0: Modulator: Mode: afsk Bits/s: 1200 Freq 0: 1200 Freq 1: 2200 Differential: selected

Demodulator: Mode: afsk Bits/s: 1200 Freq 0: 1200 Freq 1: 2200 Differential: selected

Packet IO: Mode: MKISS Interface: sm0 Callsign: mycall IP address: 10.0.0.1 Network mask: 255.255.255.0 Broadcast addr: 10.0.0.255

I also set up /etc/ax25/axports to have:

sm0 mycall 1200 255 7 144.39 APRS (1200 bps)

Finally, I made sure Avahi was set to ignore sm0. This is easier than it was prevously - now you just add:

deny-interfaces=sm0

to /etc/avahi/avahi-daemon.conf

Once that’s done, don’t forget to chmod 4755 /usr/bin/xastir so it can open sm0 and things are good.

Converting audio files under Linux

andrewmemoryblog@gmail.com (Andrew's Memory Blog) — Wed, 29 Dec 2010 23:14:27 -0700

Linux has mplayer, an excellent audio player. It’s also handy when you want to convert a sound file from one format to another. The secret is to use .wav as an intermediate conversion, since most audio converters know how to handle that.

Here is the magic incantation for mplayer:

mplayer -quiet -vo null -vc dummy -ao pcm:waveheader:file="output.wav" input.rm

This takes the input file and creates output.wav from it. Once you have that, it’s a simple matter of

oggenc output.wav

to get output.ogg (don’t forget to install vorbis-tools) or

lame output.wav

if MP3s are your bag.

Linux Review has a good article on converting using this technique

Speed up those boring meeting replays with mplayer

andrewmemoryblog@gmail.com (Andrew's Memory Blog) — Wed, 29 Dec 2010 23:14:27 -0700

It’s been a while since I looked at the man page for mplayer. Ubuntu has finally included something I’ve wanted for a long time.

Every now and then I have to listen to pre-recorded meetings. Since I usually think faster than the speakers can talk (“umm, uhh… could you go to the next slide please?”) I like to speed things up.

I used to have to use sox to change the playback speed without changing the pitch, but now it appears it’s built into mplayer, which makes it much easier.

Here’s how to do it:

mplayer -af scaletempo -speed 1.3 boringmeeting.mp3

This plays back at 1.3 times the usual speed, which is good for most speakers. Really slow ones will benefit from -speed 1.5.

When I was young, I had an LP with the song “Twilight Zone” by Golden Earring on it. I used to listen to that at 45 rpm instead of 33 rpm because it made it sound more urgent. That would be -speed 1.363 if you’re playing at home.