Speech with ABR vs VBR

2007-01-16 02:57:05

This is my first post, so can I say what a fantastic resource this site and forum is.

Our company is looking at setting up audiobooks for digital download.

Over the past week I have been playing around with various --abr switches in Lame. As most of the searches of forums like this one seemed to agree ABR was the best option for spoken word, I settled on --abr 56.

Imagine my suprise when I coverted the same file in iTunes VBR at 56kbps, coming in at around the same file size it sounded better than Lame. I went back to Lame and tried -V 8 --vbr-new and the resulting file sounded better than both and was smaller than both.

A lot of the posts recommending ABR were a few years old, has the prevailing wisdom on best settings for speech changed with the latest version of lame?
Is the problem some players can have with VBR still relevant? The new iTunes 7 looks to have fixed some of the problems users were having with VBR.

Any thoughts and opinions on this subject would be greatly appreciated.

Cheers
Ben

Speech with ABR vs VBR

Reply #1 – 2007-01-16 03:20:53

My trials let me to adopt -V 8 at 22kHz, mono, for spoken word recordings. I find it very hard to tell any difference between professionally recorded audio books on CD and their encoding at this setting.

Since I do the conversion to mono and resampling to 22kHz before LAME encoding, I don't know if LAME does as good a job at that.

Speech with ABR vs VBR

Reply #2 – 2007-01-16 04:34:33

Speex (http://www.speex.org) would be ideal for audiobooks and has a much better quality/file size tradeoff than MP3 with bitrates as low as 4 kbps.  Like Vorbis and FLAC, Speex is designed to be patent and royalty free.

However, if iTunes integration is what you're after, Speex is not really an option.  Yet another case of Apple turning its back to superior technology...

Speech with ABR vs VBR

Reply #3 – 2007-01-16 04:42:39

Check out:

http://www.hydrogenaudio.org/forums/index....c=47303&hl=

For audiobooks, I use:

-V 7 --vbr-new --strictly-enforce-ISO

I use the "strict enforcement" switch for the reason that you mentioned. Some hardware players may have problems with LAME VBR. I noticed, for example, that my 1G ipod nano had some problems with VBR (even with the firmware update), but they went away after I experimented with the "strict" switch.

Speech with ABR vs VBR

Reply #4 – 2007-01-16 05:16:06

Thanks to eveyone for your replies.

I saw Speex but unfortunately we have to stick to mp3, to allow for compatability to the most number of players in what is already a niche market.

Our orignal master files are already mono but we will resample before encoding.

The strict-enforce is a great suggestion, will include that in future tests.

Cheers
Ben