Steven Buehler wrote:
> Think of it in terms of an MP3. Telephone voice quality is 8Kbps; FM radio
> is roughly equivalent to 22KHz, 56Kbps; CDs are 16-bit (24-bit for HDCDs)
> 44KHz, 128Kbps, whereas DVD AC3 audio is 16 or 24-bit, 48KHz, 224Kbps.
Redbook audio CDs are PCM 16-bit, stereo, at 44.1KHz... that's about
1.4Mbit, not 128Kbit. Raw digital audio is HUGE. Think .WAV files (raw
RIFF encoded digital audio), and you begin to get the idea.
When you get beyond basic raw PCM audio, you're starting to use audio
codecs which use lossy compression to cut the bitrate to something
reasonable to manage.
> The audio format used in VideoCDs is also slightly different from CD
> quality.
VCDs are MPEG1, SVCDs are MPEG2. DVDs are MPEG2. Typically, the audio
tracks in MPEG2s are encoded as "Dolby" AC3, but not always (there is a
native MPEG2 audio format as well). If anyone has a more thorough
breakdown than this, I'd really enjoy hearing a factual summary.
The format you think of as "MPEG3" is actually "MPEG1 layer 3", an
alternative audio codec for MPEG1.
>>[eben@pc eben]$ echo '3k 16 2* 44100* 1024 1024*/p' | dc
>>1.345
>>
>>So about 1.3 Mbps, unless my math is off.
Your math is very close.
-- - Ian C. Blenke <icblenke@nks.net> (This message bound by the following: http://www.nks.net/email_disclaimer.html)----------------------------------------------------------------------- This list is provided as an unmoderated internet service by Networked Knowledge Systems (NKS). Views and opinions expressed in messages posted are those of the author and do not necessarily reflect the official policy or position of NKS or any of its employees.
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