Subject: Re: Ogg (Tremor) on low-end devices - msg#00169

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Re: Ogg (Tremor) on low-end devices

Hi, >I added some descriptions to the "libraries" tables, to make sure non- >devs know what those are good for. > >Porters, please fill in those tables, or tell us what to fill in for >you! GP32 and GP2X added to the tables and the port infobox template is updated and used on those ports (and WinCE I notice). >Regarding the list of platforms: First off, maybe we should sort it >alphabetically? Also the list is incomplete, several ports are >missing (OS/2, Maemo, Solaris, ...). Seems a good idea, I guess platform is anything we provide binaries for rather the something as specific as a port/backend? Well that is how I see platform anyway ;). Cheers, John ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/

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Re: Ogg (Tremor) on low-end devices

Am 29.06.2007 um 15:39 schrieb Robin Watts: > Hi all, > > Sorry for not having replied to this sooner, but it appears that > emails aren't making it to me from this list :( > > To summarise what I think the state of play with Tremor/Tremolo is: > > * Tremolo is an (my) ARM optimised version of v1.0 of Tremor. It > runs faster than Tremor - my timings for how much are probably a tad > bogus due to the hardware I was testing it on, but I believe it to be > significantly faster. > > * Tremor has been upgraded a couple of times with bug fixes (it's > now at 1.0.2), and I've pulled those fixes back into Tremolo. Sounds nice, but is this lib available under a license that makes it possible to use it? Did anbyody perform tests with it? And anyway, I still am not quite sure which of our ports support Ogg, which MP3, and which both/neither... ;) > > * Tremor has also been upgraded with a low memory mode and a low > accuracy mode. The low memory mode, I haven't looked at in detail. > The low accuracy mode (which saves 50K of lib size due to reduced > tables) reduces the quality we get out. Supposedly it saves 15% of > CPU. > > * Tremolo has not been updated with the low accuracy mode, and I'm > in two minds as to whether it's really a good idea - one of the aims > of Ogg Vorbis is superior audio quality - do we really want to throw > that away in exchange for faster decoding? Want, no. But if it's the difference between being unable to use Ogg at all, and being able to use it... ? > Anyway, my belief is that > Tremolo is still faster, as the tremolo ARM coding should be worth > noticably more than 15%. Fine. For the ARM ports at least (PSP has a MIPS R4000, for example). And of course even those 15% might be not enough (anybody know about the situation on the DS, for example?). > * The thesis referred to in the links posted by Fingolfin earlier is > interesting, but it's main claim appears to be "We used FFT instead > of MDCT and it went 8 times faster". It's a slightly suspect claim as > they apparently used an assembly FFT on a DSP and compared the time > to using the existing MDCT code on the same DSP, where the existing > MDCT is written to make use of a 32*32 -> 64 operation that that DSP > didn't provide. Aye, true, and well-discussed in the thread I posted a link to. However, the point he made also was that highly optimized FFT implementations exist for many systems, often the system vendors spend considerable amounts of energy to tweak those to the max, so being able to reap that benefit can pay off. Did you take a look at the other patches which supposedly improve efficiency? Cheers, Max ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/

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Re: Ogg (Tremor) on low-end devices

Hi Kostas, >I was thinking more of a page under platforms (say Platforms/Overview) >where the ports summarize the features they support, from ScummVM's >point of view. Sounds a lot more flexible, form the start of a 'global cheat sheet' for all platforms :). Do you want to make a start on it? Gets my vote :). John ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/

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Re: Ogg (Tremor) on low-end devices

Am 29.06.2007 um 15:39 schrieb Robin Watts: > Hi all, > > Sorry for not having replied to this sooner, but it appears that > emails aren't making it to me from this list :( > > To summarise what I think the state of play with Tremor/Tremolo is: > > * Tremolo is an (my) ARM optimised version of v1.0 of Tremor. It > runs faster than Tremor - my timings for how much are probably a tad > bogus due to the hardware I was testing it on, but I believe it to be > significantly faster. > > * Tremor has been upgraded a couple of times with bug fixes (it's > now at 1.0.2), and I've pulled those fixes back into Tremolo. Sounds nice, but is this lib available under a license that makes it possible to use it? Did anbyody perform tests with it? And anyway, I still am not quite sure which of our ports support Ogg, which MP3, and which both/neither... ;) > > * Tremor has also been upgraded with a low memory mode and a low > accuracy mode. The low memory mode, I haven't looked at in detail. > The low accuracy mode (which saves 50K of lib size due to reduced > tables) reduces the quality we get out. Supposedly it saves 15% of > CPU. > > * Tremolo has not been updated with the low accuracy mode, and I'm > in two minds as to whether it's really a good idea - one of the aims > of Ogg Vorbis is superior audio quality - do we really want to throw > that away in exchange for faster decoding? Want, no. But if it's the difference between being unable to use Ogg at all, and being able to use it... ? > Anyway, my belief is that > Tremolo is still faster, as the tremolo ARM coding should be worth > noticably more than 15%. Fine. For the ARM ports at least (PSP has a MIPS R4000, for example). And of course even those 15% might be not enough (anybody know about the situation on the DS, for example?). > * The thesis referred to in the links posted by Fingolfin earlier is > interesting, but it's main claim appears to be "We used FFT instead > of MDCT and it went 8 times faster". It's a slightly suspect claim as > they apparently used an assembly FFT on a DSP and compared the time > to using the existing MDCT code on the same DSP, where the existing > MDCT is written to make use of a 32*32 -> 64 operation that that DSP > didn't provide. Aye, true, and well-discussed in the thread I posted a link to. However, the point he made also was that highly optimized FFT implementations exist for many systems, often the system vendors spend considerable amounts of energy to tweak those to the max, so being able to reap that benefit can pay off. Did you take a look at the other patches which supposedly improve efficiency? Cheers, Max ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/