Convert Audiobook 16kbs 44.1khz HE AAC

[PetrusV]

I found an audio book that has absolutely amazing audio quality with an incredibly small size. (https://www5.zippyshare.com/v/9NqNxN5X/file.html)

When I use mediainfo to analyze it, I see that it was encoded as 16kbs, 44.1khz with libfdk:
https://prnt.sc/xeqPM19FyS5Z

I've tried dbPowerAmp and ffmpeg and can get it the same 16kbs and 44.1khz, but not the same quality.

Can someone please tell me how to achieve this amazing compression and quality?

[dellsam34]

Depends on the quality of the original sound, Those audio books producers use professional studios and high end gear in a well noise isolated rooms, so the recording is of a high quality to begin with so compression is not going to take away much, I'm not sure what audio you are trying to work on but if you are using a smart phone to record your voice than it is not a good idea.

[Cornucopia]

I have a suggestion (based on years of audio editing).: Remove "air" between large gaps of phrases, and replace with digital silence. Do leave some "important" inhalations and lip sounds in for naturalness, but otherwise you can drop a lot, and in doing so, you can easily reduce the size of your overall clip, because it is "repeating" those segments, without having to keep them in the overall bytesize, or without necessarily reducing quality further.

Scott

[mrbass]

I've made over 1,000 audiobooks maybe even 2,000. I used to be into m4b 32kbps chaptered audiobooks. I've moved on though to 16kbps opus chaptered audiobooks.

To make an opus chaptered audiobook you must make sure all audio chapters are of the same bitrate and sample rate otherwise the chapter times will be off.

If not sure then process all of them like so with ffmpeg or videomass ...I use videomass (ffmpeg frontend)
-c:a libopus -vbr off -b:a 32k -ar 48000 -af dynaudnorm,aformat=channel_layouts=stereo

Now you have .opus audio or the mp3s if you're sure they are uniform
using freac choose Encode to single file, choose Voice in opus encoder and 16kbps and don't use VBR.

Under Joblist
author = Artist and use drop down arrow to Use for all selected tracks
title = Album and use drop down arrow to Use for all selected tracks

Under tags | Albums
check Artist and Album if there are many tags under albums you can use

Cover Art click Add and add a jpg or png for a cover image.

Now playback with VLC on ios, android, mac, win, linux to navigate via the chapters.
Make sure in settings Continue audio playback is set to always.

MusicBrainz Picard to remove most unwanted metadata. Also in settings toolbar set Parse filenames
this way you set your chapter names to be the same as the file names.
Then just set again Artist, Album Artist for Author and Album for Title then click SAVE.

Once you've made an opus chaptered audiobook you can use MusicBrainz as a chapter editor if you made a mistake.

Quick tips
to clean your dirty audio use the free Oceanaudio

for just like a hiss but not too bad try in videomass (also try highpass=500 and lowpass=1000)
-c:a libopus -vbr off -b:a 32k -ar 48000 -af highpass=200,lowpass=3000,afftdn,aformat=channel_l ayouts=stereo,volume=12dB,dynaudnorm

to automatically remove silence of more than 5 seconds

-c:a libopus -vbr off -b:a 32k -ar 48000 -af highpass=500,lowpass=1000,afftdn,aformat=channel_layouts=stereo,volume=12dB,"silenceremove=start_periods=1:stop_periods=-1:start_threshold=-50dB:stop_threshold=-50dB:start_silence=1:start_duration=2:stop_duration=5:detection=peak",dynaudnorm

People are audiophiles and they're nuts ..way much overkill for high bitrates...opus codec is superior at lower bitrates even compared to FDK-AAC. If there is some music yes it will sound bad...this is for speech, talking, audiobooks and you can't beat the filesize. For example 217MiB 30h 38m, 111MiB 15h 46m, 649MiB 91h 39m, 10MiB 1h 24m


No limit on chapters ...I've made some with over 1,000 chapters but for those must use VLC on phones to scroll. I'd keep max chapters to 105 if you plan on accessing them on a computer since it'll usually be able to display all of them as long as one has like 1600x900 resolution. Higher resolution obviously can display more chapters.

[PetrusV]

Thanks for all the feedback, I really appreciate it!

I created my own audiobook with high kbs which sounds great.

I am able to produce a 16kbs opus without audio loss.

But I want to know how to do it as 16kbs 44.1khz HE AAC m4b. Clearly it is possible as the file I provided is done like that. I just need to figure out HOW they managed to encode it like that without any quality loss.

When I try, it sounds terrible.

[mrbass]

Thanks for all the feedback, I really appreciate it!

I created my own audiobook with high kbs which sounds great.

I am able to produce a 16kbs opus without audio loss.

But I want to know how to do it as 16kbs 44.1khz HE AAC m4b. Clearly it is possible as the file I provided is done like that. I just need to figure out HOW they managed to encode it like that without any quality loss.

When I try, it sounds terrible.

Use m4b-tool

m4b-tool merge -v --artist "Tolkien" --name "Lord of the Rings" --use-filenames-as-chapters --no-chapter-reindexing --audio-bitrate 16k --audio-samplerate 44100 --audio-codec aac --audio-profile aac_he_v2 --jobs 4 "/home/mrbass/Music/lotr" -o "Lord of the Rings.m4b"

[PetrusV]

@mrbass WOW WOW WOW!!! This is EXACTLY what I had been looking for! Took me a while because I was battling to get Ubuntu going on Windows 11, but now that it's done this was perfect!!!

[Mohammad Bennett]

Please tell me, if m4b-tool will work on the Windows 11 command line, or do I need to install Ubuntu on a virtual machine? I want to make my own good quality audiobook "It Ends with Us" by Colleen Hoover, because it impressed me a lot with the story. I found out about it at https://gradesfixer.com/lit/it-ends-with-us/ when I needed to explore the themes in my class and just fell in love with this book. And it seems that using m4b-tool is the best way to create audiobooks with great sound and easy navigation.

[PetrusV]

Please tell me, will m4b-tool work on the Windows 11 command line, or do I need to install Ubuntu on a virtual machine?

The original M4b-tool cannot run on any version of Windows. It only runs on Linux, and maybe on mac.

You can try this modified version for Windows, but I've not tested it myself:
https://github.com/djdembeck/m4b-merge