Splasm Software Discussions

Does Pass-through still Work?
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Author:  porpoisehork [ Mon Jul 18, 2011 11:35 am ]
Post subject:  Does Pass-through still Work?


I purchased ABB to join a bunch of audio books that are already encoded, based on pass-through (the first "key feature" on your overview page). I played around with several audiobooks and could not get pass-through to work. When re-encoding the books (MP3s recorded at 56kbps 32kHz) at the same bitrate or lower I get a tinny echo or warble in the resulting book. I can't re-encode at higher rates because of the lengh of the audiobooks (I really don't want to have to break them up into multiple files, which is why I bought ABB). I also do not have access to the original CDs any more to re-rip them as they have been passed around my family, and subsequently destroyed by careless users :(

While digging around the forums I found several posts relating to pass-though with iTunes audio:

From http://www.splasm.com/forum/viewtopic.php?f=13&t=3515&p=6250&hilit=pass+through#p6250
Audiobook Builder can pass through AAC files, if all of your files in your project are the same bit rate, for instance 256 kbps AAC.

From http://www.splasm.com/forum/viewtopic.php?f=13&t=2939&p=5273&hilit=pass+through#p5273
I would choose a quality equal to or greater than what you have set in Audiobook Builder. Audiobook Builder used to be able to pass through AAC audio from iTunes, but Apple changed the way iTunes AAC is encoded and the bitrate varies just enough to throw it off. iTunes audio will have to be re-encoded.

From http://www.splasm.com/forum/viewtopic.php?f=14&t=3487&p=6147&hilit=pass+through#p6147
This used to work, until Apple made some changes in how imported files from CDs were encoded using iTunes. They now use a default 'Average Bitrate' instead of a constant bitrate, which kills the ability to pass through these types of files using Audiobook Builder. If you do need to use iTunes, I would recommend importing using a slightly higher bitrate than what you plan to use for your final book, and Audiobook Builder will have a cleaner file to work with when it needs to compress it again.

The first post above from June 9th of this year seems to indicate that it does. If so, my questions are under what circumstances can I get pass-though to work?
  • What encoding software/codecs does ABB use? When I convert the files to AAC in iTunes 10 I don't get any of the artifacts (or they are at least much less noticable) than the output I get using ABB at the same settings. Re-encoding the files in iTunes and building the book in ABB would be an option, if ABB would support iTunes audio.
  • What version of iTunes did Apple change the behavior in that now forces iTunes audio to be re-encoded no matter what? If I use an older version of iTunes can I re-encode my MP3's as AAC audio and then join them with ABB?
  • What other encoding software can you reccomend for me to be able to do this?
  • Do you have any other suggestions on how I can convert the files withouth any of the audio artifacts I'm getting now with ABB, knowing that I'm starting from MP3 files at 56 kbps / 32kHz?

Thanks for any guidance you can provide.

Also, I would ask that you update your product information page and FAQ to more accurately reflect under what circumstances pass-through actually works, especially since you have it listed as the first "Key Feature" of the product.
Audio File Joining: Already ripped your CDs to MP3 or M4A? Don't suffer through it again - drag your audio tracks straight to Audiobook Builder. There's no need to re-encode M4A or M4B files when they're in the same format and have a constant bit rate - Audiobook Builder can quickly join them together.

I purcased the product and spent most of my weekend trying to convert files based on that feature. From postings in the forum it looks like pass-through never worked with MP3s and no longer works with iTunes. Since this is Mac-based software this feature statement seems very mis-representative of the product to me.


Author:  Randy K. [ Mon Jul 18, 2011 5:26 pm ]
Post subject:  Re: Does Pass-through still Work?

You are correct that Audiobook Builder never allowed pass through with MP3 files. The language used in our description is still accurate:

"Audio File Joining: Already ripped your CDs to MP3 or M4A? Don't suffer through it again - drag your audio tracks straight to Audiobook Builder. There's no need to re-encode M4A or M4B files when they're in the same format and have a constant bit rate - Audiobook Builder can quickly join them together."

The first sentence does not mention pass through and was never meant to push the idea of pass through as an option for MP3 files. The idea behind it is that any audio file can be dropped into your project and used without having to re-rip your files from CD. The final file will still have to be encoded as an AAC file to take advantage of chapter art, chapter markers and other Audiobook-centric features.

The second sentence does mention the idea of pass through, but outlines that it must be constant bitrate. iTunes now uses average bitrate which is no longer compatible with pass through. Those files from newer versions of iTunes will have to be re-encoded at the cost of some time and quality just like MP3 files. Any constant bitrate AAC files can be passed through no matter what application that created them (Older versions of iTunes, QuickTime, Audiobook Builder, or other audio encoding application). We are not quite sure which version of iTunes switched the encoding style from constant to average bitrate.

Audiobook Builder uses QuickTime to encode Audio. iTunes may also be using HE-AAC encoding, which can give better results at lower bitrates when compared. We have HE-AAC support on our list for support in the future.

The only real option to avoid the warble would be to try a custom quality that is slightly higher than the original, and try that. If it still sounds off, bump up the quality and try again. The lower quality you keep your build at, the longer the files can be. The reason there is a limit on file lengths at any given quality is because iPods, iPhones, and iPads are incapable of playing back files over a certain length at a given quality. It all has to do with the 32 bit sample limits inherent in these products.

We of course never intend to mislead customers into thinking Audiobook Builder will do something that it can't. If you feel as if you cannot use Audiobook Builder in its current incarnation, please email us at support@splasm.com and we will get started on a refund for you. We do appreciate the questions and hope some of this helps answer them.

Author:  porpoisehork [ Mon Jul 18, 2011 9:30 pm ]
Post subject:  Re: Does Pass-through still Work?

I apologize if it came across as if I was accusing you of intending to mislead your customers. I don't think it was intentional at all, I just think the documentation / FAQ on your site never got updated (which is very common) when you found out incompatibilities / issues over time. While I agree the statement is technically correct, this is an Apple product and iTunes is the default media player for OS X. If your product has incompatibilities it would be nice to list them in the FAQ so future users don't end up wasting time on something you already know won't work. I admit I should have probably done more research and read through the forums first. I made an assumption that it would work with iTunes given the description, but I think it's an assumption a lot of prospective customers would make given it's working.

ABB is a very nice product, especially for the price, and works very well technically. I had no issue with it other than pass-though not working, and it has more options and is much more stable than Join Together. I think it will work great for my new audio books that I have the CD media for, unfortunately that wasn't what I bought it for last weekend.

Thank you for your prompt reply.

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