YouTube Audio Again (and ABX again)

Thursday, October 4th, 2012

In a previous entry discussing YouTube audio I mentioned that Google/YouTube changes the details of their upload formats, transcoding, and streams without much fanfare. Happily all the changes I’ve seen so far have been toward higher quality, and lately they’ve upgraded the audio streams again.

I recently uploaded a set of clips from our guitar party, encoded as 720p/30 H.264 video and PCM 48khz/16 bit audio. When I pulled one of the 720 streams down from YouTube and examined the specs with Mediainfo I discovered that audio is now returned as a 192 kbps AAC stream. This is generally considered to be the audible equivalent of an uncompressed file for nearly all material. In other words, this level of compression using this codec should sound just like the original uncompressed file.

ABX for the Answer

I still strongly believe that any audio comparison should start with an ABX session, to confirm that differences are really being heard. I have observed in myself and others that even blinded, we quickly attach characteristics to a label, and once this happens we “hear” the label as much as the clip, or more.

Here are two ABX tools, one for PC and one for Mac.

In order to provide an accurate comparison between the uploaded and downloaded versions, I opened both clips in REAPER. I created a very brief extract of each file along with the full file, each rendered as an uncompressed 44.1/16 WAV file. Be sure to download these clips to listen to them, since they’re .WAV they are not intended for streaming.

joe-extract
blo-extract

joe-complete
blo-complete

So can you do 16 comparisons between these files in a double blind comparison and identify them correctly 13 or more times out of 16? Please let me know in the comments and I’ll get back to you with the ID of the clips.

Some Outside Sources

Google/YouTube has provided a bit of updated and expanded information on file formats, with specific instructions for some common video tools, recommended formats and specs, and so on. Check out the Video encoding page.

A gentleman named Nick Vogt blogs about various tech topics, and has a nice set of charts showing the progress of YouTube audio on this page. His work shows consistent progress from the bad old days of gritty lofi to today’s commercial release quality.



This entry was posted on Thursday, October 4th, 2012 at 6:51 pm and is filed under Recording, Video. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.


2 Responses to ' YouTube Audio Again (and ABX again) '

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  1. band akustik said in post # 1,

    on October 14th, 2012 at 10:44 am

    Very nice music blog. Thanks for sharing..

  2. Fran Guidry said in post # 2,

    on October 14th, 2012 at 11:39 am

    Thanks for stopping by and commenting.

    Fran

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About the Blog

    Howdy, my name is Fran Guidry and this is my Homebrewed Music blog.

    I play Hawaiian slack key guitar and recorded my solo acoustic CD at home. Most of the recording information I find on the internet seems focused on bands, drums, multitracking, and so on but my main focus is recording solo acoustic guitar. Lately I’ve been enjoying video recording along with audio, so that shows up in the blog as well.

    I’m also a guitar nut. I love big ones and little ones, handmades and factory guitars, cheap ones and expensive ones. So I’ll be sharing the fun of exploring guitars as well, along with the challenges of amplifying acoustic guitars for live performance.

    Welcome!

Philosophy

    My recording philosophy is pragmatic, skeptical, not super critical. After all, the performance is by far the most important component of a track, and every aspect of any recording is a matter of taste.

    But I do like to know “about stuff.” Back in hifi days I learned about double blind testing. I learned that we humans can easily hear differences that don’t really exist. The more I’ve learned about our human auditory system, the more I’m skeptical of what people say they hear, especially if they claim that a particular microphone or preamp or cable has some magical property.

    I’ve only been recording since 2001, and when I started I found the usual places on the internet. I sought advice and accepted it, thought I would improve my recordings by using more expensive equipment. It didn’t work.

    Two things that did seem to lead to better recordings were experience and room treatment. Getting an appealing sound is the combination of many small details, and learning those details only comes from experience. Amd the sound of the recording space is obviously a big factor.

    I’ve only recorded seriously using digital technology, but I remember trying to record rehearsals and gigs back in analog days. I don’t have any nostalgia for analog recording and playback systems at all. I think even low end digital systems can capture marvelous recordings. So when I look at gear, I look for good specs: low noise, broad flat frequency response, wide dynamic range, low distortion. I’m not interested in colorful components, mics and preamps with a sound, I want the sound to be the sound of my guitar.

    But the last word is that I’m just learning and I hope you find something useful in my posts.