- entry 2010/07/26

Noise cancelling headphones

The beans are okay, the sauce is a little watery but tastes good. At €0,69 a can, it is a fair bit cheaper than UK imports, assuming you can find them, that is.

That's when I saw a pair of headphones. Okay, I need a decent pair of headphones. I can't do much when I'm "on the road" or at work, but when sitting in bed hacking up a memory decode or looking for this oh-so-exciting porn that older people seem to thing the internet is full of (hehe... give me something in three dimensions any day), it would be nice to fire up WinAmp and here music that sounds like it was intended. Certainly in the case of 鬼束ちひろ (Onitsuka, Chihiro), her songs sound infinitely better on something that can output below 250Hz, unlike most earphones which are too small to make much of an impression at these low frequencies.

Oooh look, another video! [16:9 anamorphic, captioned; and yes, it starts with no audio, this isn't a fault]

I'm not sure quite how it works, but if you didn't catch it the first time, back up and listen to the song examples. The headphones, when "off", muffle the sound by virtue of beng between the racket and my lugholes, but they don't perform as well as proper muffs. Music is passed through, so I can listen to it without wearing down the batteries; I am listening in this way right now typing this.
However if you flick the little switch and power up the headphones, not only does the sound appear "brighter", but the bass is cut. Sometimes quite dramatically. The mower is not the best test as the higher frequency clanking is not cut much by the headphones (so they'd be useless at work where a lot of the machinery is high pitched screaming). I first noticed this incredible feat of engineering when I was giving the headphones a test run in the car. As soon as I powered up the 'phones, all the assorted rumbles a car makes simply vanished. Don't ask me, it's weird. But exceedingly cool. Not a feature I'll use much though, I'd probably wet myself if I heard those sorts of noises while in bed - assuming I'm still alive, that is. [metaphysical point - if I was dead I wouldn't be capable of 'hearing']

Kawaii-Radio is playing "I Can Fly" by Hitomi Yaida (reminds me of Alanis Morissette) and it sounds... good!

What's with the video?

If a picture speaks a thousand words, a video will save me an eternity of typing, not to mention making extremely obvious concepts that might prove hard to explain in writing alone. Now that YouTube has an option for "unlisted" videos (public, but not listed in YouTube's search results), I can upload more stuff.

How these videos are made

Acquisition
The video camera is plugged in to the Neuros OSD which captures the playback as follows:

• Video - H.263 MPEG4, 640×480, 1500kbit.
• Audio - AAC, 96kbit.

Video editing
Is performed in AVIdemux. This was chosen, basically, because my VirtualDub can't open files of .MP4 type.
Editing is a mixture of "rough" and frame accurate. I'm not putting together a TV programme here. Bits are cut out for retakes, because I thought it was cool at the time but really it was boring, or because I felt like it. I do not edit out the parts where I sound like a knob, for if I did that, you'd never see anything!

Audio editing
This is not normally required, above and beyond instructing AVIdemux to downsample to mono sound, and perhaps apply a little bit of gain...

It was, however, necessary to clean up the audio today. The first thing was to apply a lot of bass correction to the mower running. It sounds like a throaty V8 now, but it's a lot better than the lame recording performed by the video camera. Thinking back to the reason why I wanted the headphones, small earpieces are absolute crap at reproducing decent bass. Likewise, small microphones are equally crap at recording it, as as it was sorta essential to the point I was making...
For this, I spat the audio track to a PCM WAV file and used Nero Wave Editor for most of the tidy-up. The part that was difficult was merging the audio into the existing recording. I couldn't figure out how to make it work, so I used Audacity and did some cutting and pasting, then saved the results to paste back in to Wave Editor.

Speaking of audio - Kawaii-Radio has just played a really sweet song, which is greatly improved by having decent bass. ☺ It is a cover of "Watarebashi" by Maki Goto. There's a copy on YouTube at http://www.youtube.com/watch?v=bP5HGftonFc.

Encoding
Encoding is performed right from AVIdemux as follows:

• Video - H.263 MPEG4 (XviD), 640×480, 1200kbit.
• Audio - MP3, mono downmix, 96 or 128kbit.

The container is .AVI.
This is the file uploaded to YouTube.

Aspect ratio
There is a small complication in the fact that the encoding is anamorphic. There are two ways to approach this problem. The cheap'n'cheerful way is to set the Display Aspect Ratio (DAR). This means, we don't give a crap about what the source video is, we want it to be shown at xx:yy.
The more complex (and professional) way is to specify the aspect of the source, and from this the correct display sizing can be inferred. Unfortunately it is a mammoth pain in the ass to get right, because rather than worrying about the way it is to be displayed, we worry about the pixels themselves, hence this is called the Pixel Aspect Ratio (PAR).
The big problem with PAR is you have to think long and hard about the relationship. For example, there are three common ways to record a PAL video signal. The first is full-frame, which is 720×576. The second is the highest resolution most PVRs manage, which is 704×480. Finally, the resolution I usually use (because less pixels at a given bitrate means slightly better compression quality, you won't notice 64 pixels horizontally, but you might notice the difference in quality), it's 640×480.
Dividing width by height, 720×576 is 1.25, 704×480 is 1.46', and 640×480 is 1.33'.
What this means is that the exact same thing recorded from the same source, and eventually displayed the same way, has three very different aspect relationships. This is best described in the fact that for 704×480 and 640×480, the height is exactly the same, but the width is wider. This does not mean the picture is stretched, for it is corrected for the eventual display. It is, shall we say, a "carrier". Not a lot of digital video is supposed to be displayed at its recorded resolution (a number of DVD rippers preserve the height but compress the width; our eyes are less sensitive to this; and back circa 2004, Sky News Active used this method to fit two full-screen 'channels' into one real channel). Videos are watched as 4:3, 16:9, or 21:9. The aspect of the source is not relevant any more.
How did I arrive at 64:48? Trial and error. You'll notice it is a tenth of the actual size, and 1.33' relationship. How does this flag the output is 16:9? Would 32:24 work just as well? Uhhh... You got me. It was just a random test (about my twentieth experiment) and it worked. I'm not going to work out why, I'm just going say "oh, okay" and get on with it.
It would be nice to be able to specify 16:9 and let the software worry, but AVIdemux's XviD encoder doesn't see it like that. Oh well.

You might, logically, ask me why I don't just use the camera in normal 4:3 mode, work with 4:3 video (the Neuros OSD flags the videos as 4:3 based on an assumption, an assumption which is actually wrong for most of my recordings!), and output a 4:3 video.
The answer is obvious. I've always been a supporter of widescreen; preferring 16:9 DVDs even when all I had was a crappy 14" TV. I record most stuff off the TV in 16:9 anamorphic (so it can be displayed correctly on widescreen devices, or letterboxed to legacy equipment). YouTube itself has moved to being widescreen-based, as have most major broadcasters. You'll have to look hard in supermarkers and such to find a traditional square TV... about as hard as you'll have to look to find a CRT one!
The little (gimmicky?) 16:9 wide mode of my video camera was waiting for this day. Do not expect to see anything from me presented in 4:3 unless it was recorded previously.

Captioning
It is not hard to write up a subtitle file. It, actually, impresses/depresses me to find that subs for an hour and a half of Japanese animé results in a tiny file. To give you an actual example, The Graveyard of the Fireflies (Studio Ghibli) runs for 1h24. The subtitle file, complete with timing codes, is 39K. Somehow you expect it to be bigger.

The problem, and the time-consuming bit, is the "timing". The correct matching of the subtitles to the audio. In this case we're talking resolutions of a tenth of a second.

Why do I caption? I understand myself, others understand me, but that doesn't mean that everybody understands me. Some people, also, like to watch stuff with subtitles. I used to do this a lot when subs were on teletext, and I could watch without affecting the recording (the problem with getting your satellite box to subtitle is this will be present in recordings...). I don't caption everything, but when I have the time, I try to write up a subtitles file. It is also of use to those with disabilities, though I accept that it would be a rather valid point to say a deaf person probably won't have a whole lot of use for noise cancelling headphones!

Original media Destroyed. I tape over the original recordings (once they've served their purpose...) and I discard the .MP4 versions after editing. The only thing kept (and subsequently lost ☺) is the resultant .AVI file. Once it's been sent to YouTube, that's that. Of course, I stand to lose the content if I can't find the copies and YouTube dies, but in that case I think there will be a lot of people worse off than me. My videos are intended to complement, not replace, my b.log. Contrast this with, say, Natalie at communitychannel who's like the biggest video blogger going, and exists pretty much entirely within the realms of YouTube. Besides, Google not having backups? Come on...

Well, I hope this has given you an idea of the steps involved in making a video to go with my b.log. I know some people switch on their webcams and spout balls directly down the line, but I like to think I have a little bit more finesse than that. Oh, and location shooting too! ☺

Your comments:

Please note that while I check this page every so often, I am not able to control what users write; therefore I disclaim all liability for unpleasant and/or infringing and/or defamatory material. Undesired content will be removed as soon as it is noticed. By leaving a comment, you agree not to post material that is illegal or in bad taste, and you should be aware that the time and your IP address are both recorded, should it be necessary to find out who you are. Oh, and don't bother trying to inline HTML. I'm not that stupid! ☺ ADDING COMMENTS DOES NOT WORK IF READING TRANSLATED VERSIONS.
 
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Rob, 27th July 2010, 21:00

At some point I really must watch some of your videos.. means digging out the headphones.. lol.    But you think videos stay on YouTube forever? They get pulled all the time. Try looking (warning: topical reference here) for kerligirl13's original videos..

Rick, 27th July 2010, 21:23

Yeah... I think controversial videos are likely to be pulled if they get enough reports, or lots of unwanted media attention. That said, an "unpopular" 11 year old with apparently unrestricted access to YouTube? Ouch.    I put unpopular in quotes - been there. Some asses decide you don't fit in, and it's downhill from there...    As for the video above, you don't need headphones. Switch sound off and turn captioning on. ☺

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