Rockbox General > Rockbox General Discussion
Question about which Sansa I should try to buy.
OzziePants:
I have read the Buyer's Guide and, from what I can tell, Sansa products seem to be what I want.
I used to have an old Sansa Express and it worked...not well...but it worked.
The features I would like to be able to use in what I buy would be:
1. MicroSD/microSDHC memory support. Pretty sure e200v1/v2, c200v1/v2, and Fuzev1/v2 all support this.
2. USB cable to charge the player as well as transfer files. Pretty sure e200v1/v2, c200v1/v2, and Fuzev1/v2 all support this.
3. HE-AAC support. This is what is the main issue.
I haven't found what type of CPU c200v1/v2 or Fuzev1/v2 uses, but I did find this on Wikipedia.
--- Quote ---CPU v1-24 MHz (up to 80 MHz with Rockbox Firmware) v2-200mhz
--- End quote ---
Does that mean v2 is is over 100 times slower than v1? I guess this doesn't mean that HE-AAC decoding will be over 100 times worse on the v2 than v1 whenever Rockbox for Sansa AMS is ported completely but that seems like a huge difference in CPU speed.
And is there anywhere that list the CPU speed for c200v1/v2 or Fuzev1/v2?
Additionally, I was interested in using HE-AACv2 probably at 18kbs since I mostly want to use it for Audiobook CD's.
Would I be correct to assume that such a low bitrate would make decoding the files properly without skipping more likely?
Also, can anyone explain why for the iriver H10 5GB from the http://www.rockbox.org/twiki/bin/view/Main/CodecPerformanceComparison
AAC's realtime values were equal to the single HEv2-AAC's realtime value but for the iriver H340(60GB Drive) , AAC's realtime values were closer to HEv2AAC's realtime value?
Would it be possible that the comparison test for the iriver H10 5GB's test was a fluke?
saratoga:
--- Quote from: OzziePants on June 20, 2009, 02:39:48 PM ---I have read the Buyer's Guide and, from what I can tell, Sansa products seem to be what I want.
I used to have an old Sansa Express and it worked...not well...but it worked.
The features I would like to be able to use in what I buy would be:
1. MicroSD/microSDHC memory support. Pretty sure e200v1/v2, c200v1/v2, and Fuzev1/v2 all support this.
2. USB cable to charge the player as well as transfer files. Pretty sure e200v1/v2, c200v1/v2, and Fuzev1/v2 all support this.
3. HE-AAC support. This is what is the main issue.
I haven't found what type of CPU c200v1/v2 or Fuzev1/v2 uses, but I did find this on Wikipedia.
--- End quote ---
Check our wiki. Theres plenty of information there.
--- Quote from: OzziePants on June 20, 2009, 02:39:48 PM ---
--- Quote ---CPU v1-24 MHz (up to 80 MHz with Rockbox Firmware) v2-200mhz
--- End quote ---
Does that mean v2 is is over 100 times slower than v1?
--- End quote ---
How do you get that 80 is one hundred times larger then 200? But no, those numbers aren't even right. The V1 has a dual core 80MHz chip, the e200V2 a single 250MHz. They're not the same core though, so its difficult to compare to them by clock speed.
--- Quote from: OzziePants on June 20, 2009, 02:39:48 PM ---Also, can anyone explain why for the iriver H10 5GB from the http://www.rockbox.org/twiki/bin/view/Main/CodecPerformanceComparison
AAC's realtime values were equal to the single HEv2-AAC's realtime value but for the iriver H340(60GB Drive) , AAC's realtime values were closer to HEv2AAC's realtime value?
Would it be possible that the comparison test for the iriver H10 5GB's test was a fluke?
--- End quote ---
I don't know what the Hev2 file tested. It looks like probably a normal AAC-LC file. Those tests are really old though. I've improved the AAC decoder a lot since then. It won't be real time on the V1 Sansas, but probably is on the V2s.
OzziePants:
--- Quote from: saratoga on June 20, 2009, 02:51:56 PM ---How do you get that 80 is one hundred times larger then 200? But no, those numbers aren't even right. The V1 has a dual core 80MHz chip, the e200V2 a single 250MHz. They're not the same core though, so its difficult to compare to them by clock speed.
--- End quote ---
I was comparing the 24 MHz for the v1 and the 200 mhz for the v2. I didn't think comparing the 80 MHz value obtained by using the Rockbox firmware would have been fair since Rockbox doesn't work on v2.
Though I might have thought 1 Mhz equals 1000 hz and 1 hz equals 1000 mhz which is a bit off anyway. My fault.
--- Quote ---I don't know what the Hev2 file tested. It looks like probably a normal AAC-LC file. Those tests are really old though. I've improved the AAC decoder a lot since then. It won't be real time on the V1 Sansas, but probably is on the V2s.
--- End quote ---
That's good. I doubt I could find v1's very easily now anyway.
What about c200 V2's?
I see they have same SoC and that means they have the same CPU right?
I assume so from the datasheet I read for the E200v2. The datasheet link from:
the http://www.rockbox.org/twiki/bin/view/Main/SansaC200v2
seemed to be a deadlink.
I don't really want to assume too much though since I'm rather new.
animatorgeek:
--- Quote from: OzziePants on June 20, 2009, 03:21:41 PM ---I was comparing the 24 MHz for the v1 and the 200 mhz for the v2. I didn't think comparing the 80 MHz value obtained by using the Rockbox firmware would have been fair since Rockbox doesn't work on v2.
--- End quote ---
I think the problem here is capitalization. In this case, MHz is the same thing as mhz. The first one is more correct, since Hertz is abbreviated Hz. So MHz (or mHz -- not sure which is more correct) simply means one million Hertz. Based on the numbers you found on the Wikipedia page, the v2 runs at a little over 8 times the clock rate of the v1.
yapper:
MHz is mega Hertz (million cycles per second)
Lower case m is milli (1/1000th) but is not (usually) used when refering to frequencies.
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