Compressing voice recordings

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freakazoid
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Re: Compressing voice recordings

#16 Post by freakazoid » Wed Sep 12, 2012 6:22 pm

lautrepay wrote:I suppose that other players based on the BASS audio library (XMPlay, Trout, Nemp, MusicBee) will start to offer support for this new codec soon.
XMPlay already has an OPUS plugin in their forum:
http://www.un4seen.com/forum/?topic=138 ... 9#msg96799
m^(2) wrote:FLAC is rubbish. Unmaintained for years, weak and slow, except for decompression.
It gained some popularity because of missteps of competition, but I can't understand why is it growing.
I never liked FLAC either, but people started using that more. I prefer WavePack, but that never really caught on.
is it stealth? ;)

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Midas
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Re: Compressing voice recordings

#17 Post by Midas » Thu Sep 13, 2012 2:19 am

m^(2) wrote:FLAC is rubbish. Unmaintained for years, weak and slow, except for decompression.
It gained some popularity because of missteps of competition, but I can't understand why is it growing.
Non-lossy OSS? Compress once, use forever... :|
http://wiki.hydrogenaudio.org/index.php?title=Free_Lossless_Audio_Codec wrote:Pros:
  • Portable to many systems
  • Source open and freely licenced
  • Hardware support (PhatBox, Kenwood MusicKeg, Rio Karma, etc. See below)
  • Streaming support
  • Extremely fast decoding
  • Supports multichannel and high resolution streams
  • Supports ReplayGain
  • Supports cue-sheet (with some limitations)
  • Gaining wide use as successor to Shorten
Cons:
  • Compresses less efficiently than other popular modern compressors (Monkey's Audio, OptimFROG)
  • Higher compression modes slow, for little gain over the default setting.

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m^(2)
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Re: Compressing voice recordings

#18 Post by m^(2) » Thu Sep 13, 2012 8:37 am

Midas wrote:
m^(2) wrote:FLAC is rubbish. Unmaintained for years, weak and slow, except for decompression.
It gained some popularity because of missteps of competition, but I can't understand why is it growing.
Non-lossy OSS? Compress once, use forever... :|
Just like WavPack, ALAC, TTA, Shorten, ALS, SLS and arguably MAC.
Midas wrote:
m^(2) wrote:
http://wiki.hydrogenaudio.org/index.php?title=Free_Lossless_Audio_Codec wrote:Pros:
  • Portable to many systems
  • Source open and freely licenced
  • Hardware support (PhatBox, Kenwood MusicKeg, Rio Karma, etc. See below)
  • Streaming support
  • Extremely fast decoding
  • Supports multichannel and high resolution streams
  • Supports ReplayGain
  • Supports cue-sheet (with some limitations)
  • Gaining wide use as successor to Shorten
Cons:
  • Compresses less efficiently than other popular modern compressors (Monkey's Audio, OptimFROG)
  • Higher compression modes slow, for little gain over the default setting.
WavPack beats it in all regards except for power usage and hardware support in portable use. Which neither is good for anyway.
And unlike FLAC its developer supports it, so when something breaks (I've had data loss caused by a bug in FLAC, mangled order of channels), you have a chance to get it back.

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Midas
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Re: Compressing voice recordings

#19 Post by Midas » Fri Sep 14, 2012 8:44 am

I'm no audio expert, but my portable players (H3x0 & Fuze) are compatible with FLAC -- as well as with some others you mention -- and it was what was available and prescribed for many years for long-term audio preservation... BTW, it being OSS, one can hardly consider the dev under obligation to support it. But I'll be looking into Wavpack after your input, that's for sure... :)

http://www.rockbox.org/wiki/SoundCodecs

http://www.rockbox.org/wiki/CodecPerformanceComparison

http://wiki.hydrogenaudio.org/index.php?title=WavPack

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m^(2)
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Re: Compressing voice recordings

#20 Post by m^(2) » Fri Sep 14, 2012 9:00 am

Obviously, nobody is obliged to support it, but lack of a person willing to do it is a potential problem when you don't need it and can be a show stopper when you do.

And sorry, I'm being somewhat aggressive on this topic, before discovering other codecs I was a FLAC fan too, but now it really hurts me to see how much more worthwhile projects seem to stall while FLAC is growing.
Frankly, I'm not a fan of WavPack because it's too weak for my liking, but among options that do what I want them too (cross-platform portable with good software support, open source, replay gain, extended tags, cue sheets, multichannel, high resolution), this is the the strongest one (and the only that has always worked for me).

TenaciousD
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Re: Compressing voice recordings

#21 Post by TenaciousD » Sat Nov 17, 2012 2:30 am

For my music I just reduce the bitrate to around 64 or even 32 Kb/s and the sound quality is not that bad at all.

freakazoid
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Re: Compressing voice recordings

#22 Post by freakazoid » Sat Nov 17, 2012 11:49 am

TenaciousD wrote:For my music I just reduce the bitrate to around 64 or even 32 Kb/s and the sound quality is not that bad at all.
I used to do this (convert to 32kbps) when I had very little HDD space 15 years ago! ;)

If I listen to some of these files again, they sound like crap.
is it stealth? ;)

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Midas
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Re: Compressing voice recordings

#23 Post by Midas » Mon Nov 19, 2012 2:26 am

freakazoid wrote:
TenaciousD wrote:For my music I just reduce the bitrate to around 64 or even 32 Kb/s and the sound quality is not that bad at all.
I used to do this (convert to 32kbps) when I had very little HDD space 15 years ago! ;)

If I listen to some of these files again, they sound like crap.
For MP3s, the established knowledge supports that the minimum acceptable bitrate should be 128kbps -- so called 'radio quality' level; but to each, his own... :mrgreen:

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webfork
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Re: Compressing voice recordings

#24 Post by webfork » Sat Apr 20, 2013 12:08 pm

Update: my current process

Tested out LameXP's Opus compression and so far very impressed. Ran a basic comparison between the Ogg voice-specific algorythm (SPX) and Opus at roughly the same bitrate and the Opus compression was much clearer.

Part of this may come from the fact that the SPX algorthym is a few years old now and my encoder (speexdrop) hasn't been updated in a long time. Whatever the case, the toolset for Opus and the support for the codec via Mozilla makes playing the resulting files wonderfully simple.

The general conclusion is that I'll be adding another program to my process so:
  1. V2V - encoding voice memos to mono WAV format (also does normalization)
  2. Wavosaur - delete any silent areas and do some more fine-grained edition/normalization (if necessary)
  3. LameXP - encoding to Opus on 16 kbps VBR (optimize for speech in the advanced options). The lowest setting (8 kbps) wasn't bad either. None of the tin-cup or raspy-sounding audio artifacts I'm used to with a low-quality encoding.
Anyway, thanks to m^(2) for the Opus suggestion and LameXP's dev for making conversion extremely smooth.

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Midas
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Re: Compressing voice recordings

#25 Post by Midas » Mon Jan 27, 2014 5:54 am

Old topic update:

A thorough listening test has been conducted at HydrogenAudio and the results support Opus excellence...
Also, a fast resource comparing lossless audio formats, as discussed above (and which appears to imply that FLAC remains a noteworthy contender):

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Re: Compressing voice recordings

#26 Post by webfork » Thu Jan 30, 2014 6:06 pm

Excellent news, thanks.
Midas wrote:A thorough listening test has been conducted at HydrogenAudio and the results support Opus excellence...

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Re: Compressing voice recordings

#27 Post by webfork » Sat Jul 14, 2018 12:36 pm

Note that I don't think I'll be integrating this into my compression protocol for at least another year, but it's a very exciting development that I think will only improve with time...

---

What's always been important about voice recordings isn't that it's an accurate recording of the person speaking, but that what's being said is understandable. Most compression tools handle this through subtraction: taking out everything that's not within the rather thin part of the sound spectrum scope occupied by the human voice. For example, a high-pitched noise in a voice recording might not be part of the final output.

Now, a new system has come about that records sound in an exceedingly basic (and small) format and then uses an intelligent algorithm to "improve" it. This combination has given rise to a codec that could fit a whole podcast on a Floppy Disk:

Codec2: https://auphonic.com/blog/2018/06/01/co ... oppy-disk/

The technology is a neat idea on it's own, but the provided link is very well written and describes the tech with live samples. This could have huge applications for bandwidth, audio archives, poor network connections, and the use of technology in the 3rd world by a non-literate populace.

More info: http://www.rowetel.com/?p=5966

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