Clip+ and AAC

[OzziePants]

I was just wondering where I could find playback time information with respect to codec for the Clip+.

I assume since AAC is more complicated than MP3, the playback time would be less.

Also, would HE AAC playback drain the batteries more than AAC?

Actually, I guess I should check if the Clip+ and do 100% playback speed, I guess.

[saratoga]

Should be about the same for AAC and MP3, but probably worse for AAC+ since its a lot slower.

FWIW at the moment we don't have frequency scaling working on the clip+, so the difference won't be huge.  Once it goes in, MP3 and AAC will improve a lot more then AAC+.

[OzziePants]

That's fine. I doubt I'll be using HE AAC for music anyway. I mostly use it for audiobooks that I rip. I don't use Speex since it isn't as widely supported. Either way, great to hear AAC and MP3 are about the same.

[saratoga]

I've updated benchmarks for the Clipv2/Clip+ here showing how much CPU time each format needs:

http://www.rockbox.org/wiki/CodecPerformanceComparison#AMS_AS3525v2_w_24MHz_PClK_ARM926

[OzziePants]

Have I mentioned that I think you guys are awesome?

Because you guys are.

One question though.

On the last column for: Nero AAC-HE

64kaache.m4a    155.54% realtime    Decode time - 113.16s    154.30MHz

I assume that's the CPU speed required for 100% realtime playback, correct?

The CPU goes up to 240 MHz, right?

Would that means there isn't really a risk of damage/overheating/other problems playing back AAC+ files?

Only concern is that battery drain would be way higher, correct?

[saratoga]

Would that means there isn't really a risk of damage/overheating/other problems playing back AAC+ files?

Only concern is that battery drain would be way higher, correct?

At the moment theres no frequency scaling, so you're always running at 240MHz. 

Edit:  250->240MHz

[OzziePants]

Hmm, I guess running at 250 MHz isn't a major problem then.

Thanks.

[Hobbit5]

FWIW at the moment we don't have frequency scaling working on the clip+,

interesting information --> this means at the moment, codec and bitrate have no influence on battery drain, have it?

[saratoga]

FWIW at the moment we don't have frequency scaling working on the clip+,

interesting information --> this means at the moment, codec and bitrate have no influence on battery drain, have it?

As I said above, the difference is probably not as large without frequency scaling as it is with frequency scaling. 

[SheepCake]

That's fine. I doubt I'll be using HE AAC for music anyway. I mostly use it for audiobooks that I rip. I don't use Speex since it isn't as widely supported. Either way, great to hear AAC and MP3 are about the same.

I would suggest you try Ogg for your audio books, most audio books are mono or joint stereo, at q0 you will actually get 32Kbps range, and it encodes ALOT faster then aac, use the aoTuV 5.7 encoders for best results.

for lower hz range stuff you can go as low as q-2, Just a suggestion I have ALOT of audio books on my players/sd cards, and only use MP3 or AAC when the books already in that format at VERY low bitrate.

also Cook (RA) would be even better(im looking for a good encoding app to test for audio books in .ra format)

[nls]

Speex is also very good for audio books in my experience.