Help the podcast N00b

[Hypnagogue]

Audio-mavens... Right now my podcast is kind of piggish, size-wise. My 90 minute cast is 85MB in size. By contrast, Ultima Thule's 'cast of the same length is half the size (about 38MB).

Googling for answers, I found the simple suggestion that reducing the bit rate from 128 to 64 will (duh) cut the file size in half--but how much will the sound quality suffer?

Thank you for any input. I'm still trying to hammer out the technical side of this new hobby-thang I've fallen into!

[APK]

You could perhaps use variable bit rate (vbr) mp3 encoding, so the encoding automatically fluctuates, say, from 128 to 64 as needed. Will save space over a straight 128.

As for 128 vs 64 encoding, you should encode some music at both rates and have a comparison listen and see if 64 is acceptable to you and still suits your purpose. 128 is the usual bottom level for still being close to CD quality.

Also worth seeing what Ultima Thule are encoding at.

[Undershadow]

As far as I’m aware, 192kbps is regarded as the lowest bitrate for an mp3 to qualify as ‘high quality.’ That said, 128kbps is still good enough for most listeners, and I have done mixes at this rate that have gone down ok. Once you start coming down below that, you’re dealing with a considerable amount of loss through compression of the sound file. When I upload samples to illustrate a review, these are required to be 96kbps. They do the job of giving people an idea, but I wouldn’t want to listen to too much at this rate, especially when dealing with Ambient, where texture and sound colour are a major parameter. A podcast at 64kbps would be a pretty poor representation of such sounds, in my view.

[Hypnagogue]

On an admittedly slow work connection it took iTunes about 20 minutes to download my 'cast. I'd think to some folks that would be a bit of a put-off... Or perhaps that's just me.

Alan, I completely agree with you about the depth of sound or the loss thereof about such a low bitrate. And that's my worry.

[petekelly]

John,

Personally, I think 128K is the limit really. Ultimathule go for 56K - which is pushing it a bit I think.

cheers
Pete

[Hypnagogue]

Their site does mention that it's 56k. I've been jumping back and forth between mine and theirs...there's not a lot of difference in sound--then again, they've got an entire radio station's worth of tech & talent at their disposal. I'm one guy with a bad mic and a copy of Audacity!

I need Brian to weigh in on this one...how he does Quiet Sounds....

btw, any feedback on the Hypnagogue 'cast is greatly appreciated. Feel free to email me.

[cromag]

What encoder are using to get the MP3s?  Some encoders allow you to optimize for "spoken word," "music," etc., at each given bit rate.  It might help.

I always appreciate higher bit rates, but I still find Ultima Thule to be listenable.

[Brian Bieniowski]

I encode all of mine (and I need to do a new one soon!) at 128, which, for me, is the lowest sound quality I'd consider.  I would guess the podcasts are all around 70 MB a piece, more or less.  While I understand that there may be some who are still on dial-up and would be off-put by large file downloads, my assumption is that most people interested in podcasts are likely at least using DSL and can handle large files pretty well.

[mgriffin]

There is no secret or puzzle here.  First off, 90 minutes is on the long side for a podcast so you should expect a much larger file size.  128k should be a decent bitrate for a podcast.

Many of the music podcasts I've downloaded have been in the 60-80 megabyte file size range and most are 40-60 minutes.

[Hypnagogue]

Cromag: LAME encoder for Audacity.

I played around with one of the shows last night, re-sampled at 96, and it cut about 20 meg off the file with no discernible (to these ears) loss of sound.

Funny about 90 minutes being long. I was really only looking at UT, length-wise. Given the long nature of our music I figured 90 was a good way to get a decent number of artists in, get a good blend going. I may need to re-think that. I see some that run 90...some that run 30 (too short, imho!).

Then again, it seems to be going okay. I'm up to a world-dominating 20 subscribers with no complaints yet (after one whole podcast...) Perhaps we'll just let the ship sail on a bit as is, see where it drifts to. When you get right down to it, I'm having fun--and what's more important than that? :-) I haven't been this energized by a creative project in a long while.

[LNerell]

Audio-mavens... Right now my podcast is kind of piggish, size-wise. My 90 minute cast is 85MB in size. By contrast, Ultima Thule's 'cast of the same length is half the size (about 38MB).

I have to say I find Ultima Thule's podcasts unlistenable because of the low bit rate they use, they sound very harsh to my ears. I say offer both a high bit rate and a low-res version for people who use dial up. After a month or so you will see what your audience prefers.