I actually work for Rogers Wireless in Canada, and was lent a new Motorola V300 phone to try out for the week.

This thing can play back MP3s as ringtones, so I've been playing around with low bitrate LAME encoding recently.

Figuring stereo is a total waste of time (one tiny little speaker), i figured i'd just use something like:

lame --preset cbr 112 -m m --clipdetect --scale 1.2312

where this is the highest scalefactor i could use on this track without --clipdetect complaining - I want my ringtones to be loud!

Now, i noticed that lame is using a highpass of like 20,000 Hz! WTF? Shouldn't the CBR presets cut that down? Should I just add a --lowpass 15, --resample 32 or at least a -Y or something? seems like a horrid waste at that bitrate, and i'm sure this speaker can't handle anything terribly high pitched anyhow.

I would imagine a 112k mono encoding uses the same lowpass as a 224k stereo one

why would you assume that? the use of joint stereo means that it would undoubtedly sound better at 224 than the mono file at 112.

Personally, I would be surprised if 112k mono is not overkill. Since most phones are engineered for 64k voice, limited frequency range, and rather simple synthetic or polyphonic ringtones, 112K sounds like a lot.

Who knows. I could be wrong... technology is wonderful, huh?

Don't they specify what the optimal encoding is?

There is like no mention of the MP3 capabilities at all. That single 1.8 MB file i transfered took like an hour as well... damn GPRS is slow! I have no idea if the phone will handle ABR/VBR or not, and I don't plan on checking either.

Mostly I was just wondering about the weird lack of lowpass handling in the CBR presets.

hi jebus.

for my jamba usb-stick i use 3.90.3 with a bitrate of 102 (ABR, but i suppose with CBR it will be the same). From here down the LAME-presets are resampling to 32kHz. But only with 3.90.x. i noticed that with newer lameversions this isn´t so and to my ears it sounds worse.

try it. i´m really satisfied with that bitrate for my usb-stick for use in the streets.

edit:spelling

Well I discovered a developer Motorola site that suggests 64kbps mono be used for ringtones, so i'm just using

--preset cbr 64 -m m --clipdetect --scale x.xxxx

for now. Still not sure why LAME is using like 18kHz for a lowpass at such a low bitrate, but I suppose I should start a thread with a better title to discuss that, no?

64k is still quite a high bitrate for a small crappy speaker being driven very hard (I wouldn't be suprised if the ringtone speaker plays with 30% THD). You could try testing a couple of bitrates and find when the quality noticeably deteriorates.

I would guess 48k with a 10kHz lowpass would be in the right area.

This is because you are using mono. On mono, the lowpass is increased by about 60% for the same bitrate.

Try decreasing target bitrate, you will see the lowpass changing.

I see! Thanks for the clarification. I did see it drop for 64kbps to around 17kHz, but still thought that a bit high.