Audio Scriptures: Audio quality

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hg4144
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Audio Scriptures: Audio quality

Postby hg4144 » Fri Jun 04, 2010 9:44 am

I've been using the audio scriptures downloaded from LDS.org for about 6-7 years now, and just recently the quality is so annoying (I hadn't noticed before), the 32 bit sounds distorted. I've redownloaded and listened through my computer, same annoyance. So it is not my earphones, ipod, or corruption of files.

So, I downloaded the BofM from LDS audio, (free, no cost) and it is 64 bit and sounds much smoother, but I'm not sold on the voice, so far.

Does anyone know, if the Book of Mormon on CD from the Distribution Center (about $11) is of a better bit rate? I would have to convert to mp3, if it wasn't in that format already, for my iTunes.

Hopefully, it would be 64 or better!

Thanks,
Howard of Devon

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Postby rmrichesjr » Fri Jun 04, 2010 8:13 pm

By "32 bit" I take it you mean 32kbps (which means 32,000 bits per second). That's the bit rate of the MP3 Book of Mormon title page I just downloaded to check. MP3 is a lossy compressed audio format, and lossy compression always causes some loss of information/quality. Bit rate is a tradeoff between quality and space/bandwidth.

A standard audio CD (as in standards-compliant CDDA) has a data rate of 44,100 samples/frames per second, where each sample/frame contains 16 bits for each of two channels. That's a total rate of 1,411,200 bits per second. Okay, the audio scriptures are probably monaural, so that's only 705,600 useful bits per second. The CDDA encoding is lossless.

I would be surprised if the audio CDs you can buy at distribution centers have had any lossy compression used in their processing. That said, I suspect they have analog noise worth at least a couple of the least significant bits of the 16-bit sample. If compressed audio bugs you (as it does me), I think you'll be pleased with the quality of the CDs at distribution.

Did that explanation help?

JamesAnderson
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Postby JamesAnderson » Sat Jun 05, 2010 8:13 am

Many other things on lds.org's audio page are now at 64kbps. Music is encoded at 128kbps, so it is odd they have not replaced the old 32kbps files for the Scriptures with higher quality bitrate material.

In fact it is almost standard in the idustry now to encode talk audio at 64kbps, and music at 128kbps in mp3 format.

An old entry on ldsmediatalk.com and I don't know if it is still there or not, said they were planning to move talk audio from 32kbps to 64kbps on lds.org and other places where the Church had mp3 audio files. What is the status of that plan?

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gregwanderson
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Postby gregwanderson » Sun Jun 06, 2010 10:02 pm

When I first discovered the free audio book version of the Book of Mormon at lds.org (about 5 years ago) I was happy that it was free and the audio compression was not bad. But the audio quality in general sounded like these were copied from cassette tapes with plenty of tape hiss. By comparison, when I rip any recently-produced audio book from CD at 32kbps (mono) the sound quality is just fine for voice recordings (and it doesn't sound anything like a cassette tape transfer). I will have to download whatever is currently available from lds.org for the Book of Mormon audio book and compare it to what I've been using for the past 5 years.

Again, it's not the audio compression that bothers me but the tape hiss from the source used to create the digital file.

makinjeremiah
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Good Points

Postby makinjeremiah » Mon Jun 07, 2010 7:05 am

These are all good points. I believe 32k mono can be done for voice and sound acceptable overall. I'm not sure where the English source came from but recently we posted the Spanish Bible and those files are encoded at 32k mono which came directly from a hi-res digital source wav file. It'd be interesting to compare quality between that and the English.

I may have to try this in my spare time. Do you have a specific chapter that was particularly annoying?

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gregwanderson
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Postby gregwanderson » Mon Jun 07, 2010 4:01 pm

Upon further review, I see that the audio book versions of the Book of Mormon use a bit rate of 32kbps as well as a very low sample rate of 22kHz. When I claim that the audio I've encoded at 32kbps sounds "fine" I neglected to observe that I usually use a sample rate of 32kHz or 44.1kHz, which seems to make a big difference. So there seems to be some room for improvement when it comes to the Book of Mormon MP3 files.

By comparison, the audio podcast feed for the April 2010 General Conference features talks encoded at 64kbps/44.1kHz and the songs at a whopping 256kbps/44.1kHz. Very nice!

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gregwanderson
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Postby gregwanderson » Thu Sep 09, 2010 9:48 am

I did a comparison of the audio from some English scripture audio books at LDS.org and the newer audio from Spanish and Portuguese scriptures. Although the encoding specs are the same the newer audio sounds better because, it seems, the source used to create the MP3s was of higher quality. Also, the overall amplitude is significantly lower in English (like 7dB to 10dB less). That makes it particularly difficult to use these when you're listening with a portable player in a noisy environment. Worse yet is when you boost the volume to listen to the scriptures and then you switch to a pop song at the same setting. Ouch!

The English audio versions of General Conference talks or Ensign articles seem to be mastered very well too. So the only glaring problem seems to be with the English scripture MP3 files. Perhaps remastering those files can be put on someone's to-do list.

cab278
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Re: Audio Scriptures: Audio quality

Postby cab278 » Thu Jun 02, 2016 4:09 am

I know this is an old thread, but I was wondering if anyone knew if there was anywhere to download the BOM audio in a lossless format. There's a newer audio codec called opus that does really well at compressing spoken word at low bitrates, much lower than mp3 or other lossy formats. I'd like to see how much I can compress it with Opus while still having acceptable audio quality, but I need uncompressed or high quality input files.

rmrichesjr
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Re: Audio Scriptures: Audio quality

Postby rmrichesjr » Thu Jun 02, 2016 7:46 pm

I would be surprised if lossless formats were available on any Church website. One idea would be to find someone who regularly buys CDs of General Conference and beg or buy an older set. Or, perhaps Deseret Industries might have them from time to time.. I don't know for a fact that the General Conference CDs have not been processed by lossy methods, but I would guess they are most likely lossless.

Another option might be to buy old vinyl records with spoken stories. With vinyl records, speeds below 33 1/3 rpm would likely be lower quality.

cab278
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Re: Audio Scriptures: Audio quality

Postby cab278 » Sat Jun 04, 2016 10:00 am

Thanks rmrichesjr. I thought I might end up having to get the CDs. I was hoping to save the time and effort of ripping them, but it looks like they might be my best option. The vinyl records are an interesting idea, but I don't know anyone with access to a record player.


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