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Audio interview w/AI lead on Bioshock

Started by March 03, 2008 07:27 AM
11 comments, last by Rockoon1 16 years, 8 months ago
Quote: Original post by InnocuousFox
I checked the sample rate for the audio. It's 16 kbps. That's pretty low and a lot of flash players get mad at that. It's odd, however, that the same flash player on that site works for some people but not for others.


It appears that new versions of Adobe Flash have relaxed the limitations. The earliest mention I could find is Flash 9 Update 3 Beta 2.

The player applet is failing to check to see if the client plugin version supports the sampling rate of the stream, offering an upgrade in cases where it doesn't. This is probably because the applet does not have access to the specifics of the stream... thats just a guess on my part.. could just be poor coding by the widget designer.

In any event, I am not upgrading things like this on my development machine. I do partake in the evils of web development from time to time so its lowest-commons all the way.
There is a flag in the applet code that is set to "is valid bitrate" or something to that effect. I may turn it off. Again, feel free to download the file raw and do with it what you please.

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Quote: Original post by InnocuousFox
There is a flag in the applet code that is set to "is valid bitrate" or something to that effect.


To be precise..

The issue isnt the bitrate of the mp3, its the sample rate of the decoded PCM data. Bitrate really isnt related to sample rate in any well defined manner.

Your PCM data is a 16000hz time domain signal, meaning that it samples the waveform it approximates 16000 times per second.

MP3 encodes this data in the frequency domain, not the time domain. This is where bitrate comes in, by deciding how precise the amplitude and phase of each spectral component gets encoded. Your bitrate is 16 kilobits per second, which is partialy confusing the issue (16khz and 16kbps).

The issue is not in the MP3 encoding or decoding, it is in the playback of the time domain signal after the mp3 has been decoded. Flash didnt support sampling rates other than 11025, 22050, and 44100.

I assure you that the 16kbps isnt the problem, its the 16khz.

Flash also seems to have had an issue with variable-bit-rate (VBR) MP3 data, and that is another issue a web developer will need to be aware of.

Think of the sampling rates 11025hz, 22050hz, and 44100hz to be "the powers of 2 of the audio world", because quite frankly.. they are.

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