What's the meaning of "sample rate" in MP3/Vorbis/AAC?, Considering the audio was transformed |
What's the meaning of "sample rate" in MP3/Vorbis/AAC?, Considering the audio was transformed |
 Oct 7 2012, 03:44
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#1
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 Group: Members Posts: 89 Joined: 3-November 04 Member No.: 17971  |
What's the meaning of "sample rate" in MP3/Vorbis/AAC? Wouldn't it be meaningless after transform, same as bit depth?
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Oct 7 2012, 19:00
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#2
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 Group: Members Posts: 4136 Joined: 2-September 02 Member No.: 3264 |
Using a dct means you could easily drop the sample rate by a factor of 2^n. This is widely used in jpeg and some old mp3 decoders. But that's just an optimization based on how inverse transforms work. You can't actually decode to an arbitrary sample rate. Converting to the frequency domain doesn't really make much difference for sampling. You still have a well defined sampling rate In the frequency domain.
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Oct 8 2012, 23:41
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#3
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Group: Members Posts: 4136 Joined: 2-September 02 Member No.: 3264 |
QUOTE (sheh @ Oct 8 2012, 13:33)  Okay, so the original fs needs to be plugged in somewhere, but isn't it possible (in theory at least) to decode to an arbitrary sample rate < fs? QUOTE (benski @ Oct 7 2012, 13:32) Like others have said, you can decode easily to sample rates that are multiples, but you cannot decode to arbitrary sample rates without resampling. QUOTE (saratoga @ Oct 7 2012, 14:00) You can't actually decode to an arbitrary sample rate. Are you reading the replies to this thread 
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sheh What's the meaning of "sample rate" in MP3/Vorbis/AAC? Oct 7 2012, 03:44
saratoga No, the transform occurs on sampled data and so th... Oct 7 2012, 05:05
sheh I guess the way I put it does seem like a retread.... Oct 9 2012, 05:21 saratoga QUOTE (sheh @ Oct 9 2012, 00:21) Benski s... Oct 9 2012, 19:03 pdq Still. since the data are stored as frequencies an... Oct 7 2012, 14:23 [JAZ] When we say that lossy streams don't have a st... Oct 7 2012, 14:44 jensend I'm not intimately acquainted with the details... Oct 7 2012, 16:46 benski fs is part of the MDCT equation. If you didn... Oct 7 2012, 18:32 sheh Okay, so the original fs needs to be plugged in so... Oct 8 2012, 18:33 lvqcl Winamp MP3 decoder still have Full/Half/Quarter qu... Oct 7 2012, 18:56 benski QUOTE (lvqcl @ Oct 7 2012, 13:56) Winamp ... Oct 10 2012, 16:16 jensend I still think you're wrong here. Once you... Oct 7 2012, 19:57 saratoga QUOTE (jensend @ Oct 7 2012, 14:57) I sti... Oct 7 2012, 20:16 Dynamic I think one problem is that we're never doing ... Oct 8 2012, 23:04 [JAZ] Mmm.. the tranformation that (most) lossy codecs d... Oct 9 2012, 19:03 Dynamic QUOTE ([JAZ] @ Oct 9 2012, 19:03)... Oct 9 2012, 22:22 pdq So am I understanding correctly that 99.9% of deco... Oct 10 2012, 17:12 saratoga QUOTE (benski @ Oct 10 2012, 11:16) QUOTE... Oct 10 2012, 17:30 [JAZ] QUOTE (Dynamic @ Oct 9 2012, 23:22) As [J... Oct 10 2012, 17:52 saratoga QUOTE ([JAZ] @ Oct 10 2012, 12:52... Oct 10 2012, 18:20 [JAZ] Winamp with the in-house decoder (i.e. not the fra... Oct 10 2012, 18:41 saratoga QUOTE ([JAZ] @ Oct 10 2012, 13:41... Oct 10 2012, 18:55 Dynamic My recollection is that Winamp 1.7 running under W... Oct 11 2012, 16:14 sheh So sample rate matters. I suppose without being fa... Oct 11 2012, 23:20 |
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