Hi all, In a technical report about hardware implementation, I see that they use the term 25 bit depth to describe a 1-D LUT. Also on the diagram, they use the notation 25x14 on this 1-D LUT. From this, is it true that the memory of this 1-D LUT is 2^25 * 2 bytes= 64Mbytes? Thanks
Memory of depth and size of look up table?
Started by ●January 27, 2009
Reply by ●January 27, 20092009-01-27
A.E lover wrote:> Hi all, > > In a technical report about hardware implementation, I see that they > use the term 25 bit depth to describe a 1-D LUT. Also on the diagram, > they use the notation 25x14 on this 1-D LUT. > > From this, is it true that the memory of this 1-D LUT is 2^25 * 2 > bytes= 64Mbytes?In plain English, I take that to mean 14 words of 25 bits each. In jargon, it could be anything. Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 27, 20092009-01-27
Jerry Avins <jya@ieee.org> writes:> A.E lover wrote: >> Hi all, >> >> In a technical report about hardware implementation, I see that they >> use the term 25 bit depth to describe a 1-D LUT. Also on the diagram, >> they use the notation 25x14 on this 1-D LUT. >> >> From this, is it true that the memory of this 1-D LUT is 2^25 * 2 >> bytes= 64Mbytes? > > In plain English, I take that to mean 14 words of 25 bits each. In > jargon, it could be anything.It has been my experience that such dimensions are usually in "address x width" form so I would say it's 25 14-bit words, but who knows in such a case? -- % Randy Yates % "Remember the good old 1980's, when %% Fuquay-Varina, NC % things were so uncomplicated?" %%% 919-577-9882 % 'Ticket To The Moon' %%%% <yates@ieee.org> % *Time*, Electric Light Orchestra http://www.digitalsignallabs.com
Reply by ●January 27, 20092009-01-27
Randy Yates wrote:> Jerry Avins <jya@ieee.org> writes: > >> A.E lover wrote: >>> Hi all, >>> >>> In a technical report about hardware implementation, I see that they >>> use the term 25 bit depth to describe a 1-D LUT. Also on the diagram, >>> they use the notation 25x14 on this 1-D LUT. >>> >>> From this, is it true that the memory of this 1-D LUT is 2^25 * 2 >>> bytes= 64Mbytes? >> In plain English, I take that to mean 14 words of 25 bits each. In >> jargon, it could be anything. > > It has been my experience that such dimensions are usually in "address x > width" form so I would say it's 25 14-bit words, but who knows in such a > case?I normally construe "bit depth" to be akin to "bus width". Do you think that's misguided? jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 27, 20092009-01-27
Jerry Avins <jya@ieee.org> writes:> Randy Yates wrote: >> Jerry Avins <jya@ieee.org> writes: >> >>> A.E lover wrote: >>>> Hi all, >>>> >>>> In a technical report about hardware implementation, I see that they >>>> use the term 25 bit depth to describe a 1-D LUT. Also on the diagram, >>>> they use the notation 25x14 on this 1-D LUT. >>>> >>>> From this, is it true that the memory of this 1-D LUT is 2^25 * 2 >>>> bytes= 64Mbytes? >>> In plain English, I take that to mean 14 words of 25 bits each. In >>> jargon, it could be anything. >> >> It has been my experience that such dimensions are usually in "address x >> width" form so I would say it's 25 14-bit words, but who knows in such a >> case? > > I normally construe "bit depth" to be akin to "bus width". Do you > think that's misguided?No, I don't. Therin lies the inconsistency in their terminology, purportedly. -- % Randy Yates % "How's life on earth? %% Fuquay-Varina, NC % ... What is it worth?" %%% 919-577-9882 % 'Mission (A World Record)', %%%% <yates@ieee.org> % *A New World Record*, ELO http://www.digitalsignallabs.com
Reply by ●January 27, 20092009-01-27
Randy Yates <yates@ieee.org> wrote:>Jerry Avins <jya@ieee.org> writes:>> Randy Yates wrote:>>> Jerry Avins <jya@ieee.org> writes:>>>> A.E lover wrote:>>>>> In a technical report about hardware implementation, I see >>>>> that they use the term 25 bit depth to describe a 1-D LUT. Also >>>>> on the diagram, they use the notation 25x14 on this 1-D LUT.A 25x14 table would almost always mean 25 words, 14 bits per words. Not 2^25 words.>>>>> From this, is it true that the memory of this 1-D LUT is 2^25 * 2 >>>>> bytes= 64Mbytes?>>>> In plain English, I take that to mean 14 words of 25 bits each. In >>>> jargon, it could be anything.>>> It has been my experience that such dimensions are usually in "address x >>> width" form so I would say it's 25 14-bit words, but who knows in such a >>> case?>> I normally construe "bit depth" to be akin to "bus width". Do you >> think that's misguided?>No, I don't. Therin lies the inconsistency in their terminology, >purportedly."Bit depth" is pretty non-standard so that could mean anything. If they're saying 25x14 and they mean something other than 25 words in the table, that is very non-standard. Steve
Reply by ●January 27, 20092009-01-27
I just learnt that the notation 25x14 means 15 bit address for input and 14 bit address for output. So does it mean what I wrote in my OP: size of the memory is 2^25 * 2 bytes Sorry I am not in digital signal processing area, so might be it is so simple question to you, but not to me. Thanks, AE On Jan 27, 11:57�am, spop...@speedymail.org (Steve Pope) wrote:> Randy Yates �<ya...@ieee.org> wrote: > > >Jerry Avins <j...@ieee.org> writes: > >> Randy Yates wrote: > >>> Jerry Avins <j...@ieee.org> writes: > >>>> A.E lover wrote: > >>>>> In a technical report about hardware implementation, I see > >>>>> that they use �the term 25 bit depth to describe a 1-D LUT. Also > >>>>> on the diagram, they use the notation 25x14 on this 1-D LUT. > > A 25x14 table would almost always mean 25 words, 14 bits per words. > Not 2^25 words. > > >>>>> From this, is it true that the memory of this 1-D LUT is 2^25 * 2 > >>>>> bytes= 64Mbytes? > >>>> In plain English, I take that to mean 14 words of 25 bits each. In > >>>> jargon, it could be anything. > >>> It has been my experience that such dimensions are usually in "address x > >>> width" form so I would say it's 25 14-bit words, but who knows in such a > >>> case? > >> I normally construe "bit depth" to be akin to "bus width". Do you > >> think that's misguided? > >No, I don't. Therin lies the inconsistency in their terminology, > >purportedly. > > "Bit depth" is pretty non-standard so that could mean anything. > If they're saying 25x14 and they mean something other than > 25 words in the table, that is very non-standard. > > Steve
Reply by ●January 27, 20092009-01-27
A.E lover wrote:> I just learnt that the notation 25x14 means 15 bit address for input > and 14 bit address for output.Is 15 a typo? Did you mean 25-bit addresses by 14-bit outputs? That *would* be 2^25 by 14 bits.> So does it mean what I wrote in my OP: size of the memory is 2^25 * 2 > bytesThere's no need to waste two bits per entry unless it's cheaper that way.> Sorry I am not in digital signal processing area, so might be it is so > simple question to you, but not to me. Thanks,... Don't be sorry; rejoice! Jerry -- Engineering is the art of making what you want from things you can get. �����������������������������������������������������������������������
Reply by ●January 27, 20092009-01-27
On Jan 27, 2:57�pm, spop...@speedymail.org (Steve Pope) wrote:> > "Bit depth" is pretty non-standard so that could mean anything.in digital audio it's pretty common. at least with audio practitioners who record, manipulate, and master audio files of various sizes. the size (in bytes) of an uncompressed audio file is a function of various attributes which include length (in time), sample rate, number of channels, and bit depth. it basically means the word width (in bits) and normally applies to left-justified words (so increased "bit depth" means adding bits to the right and quantization usually means reducing the bit depth). r b-j
Reply by ●January 27, 20092009-01-27
robert bristow-johnson <rbj@audioimagination.com> wrote:>On Jan 27, 2:57�pm, spop...@speedymail.org (Steve Pope) wrote:>> "Bit depth" is pretty non-standard so that could mean anything.>in digital audio it's pretty common. at least with audio >practitioners who record, manipulate, and master audio files of >various sizes. the size (in bytes) of an uncompressed audio file is a >function of various attributes which include length (in time), sample >rate, number of channels, and bit depth. it basically means the word >width (in bits) and normally applies to left-justified words (so >increased "bit depth" means adding bits to the right and quantization >usually means reducing the bit depth).Thanks, this is useful to know. Steve
