From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander =?iso-8859-1?Q?K=F6nig?= Date: Mon, 25 Oct 1999 21:15:00 +0000 Subject: Re: [linux-audio-dev] Re: streaming from disk to terminatorX added (via Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: linux-sound@vger.kernel.org Paul Barton-Davis wrote: > just FYI: my C++ libsoundfile uses mmap(), but still requires > applications to "read" the data. it is significantly faster than using > read(2) internally, however, so there might be an argument for using > mmap regardless of the endianness, and then using arch-dependent > macros to fetch the data from the mmapped area. for example, on a > little endian machine reading from a little endian RIFF/WAV file, the > macros are essentially no-ops. No-ops? Do you mean you don't generate ANY code for this? If so: HOW? <..> > >- the next release of tX will allow you to load MANY (as many as you > >want) samples in multiple turntables. If all these are mmap'ed files I > >guess your disk-head will jump around like mad when playing. >=20 > actually, no more than it would if you use a 4K memory buffer :) ??? Yeah sure, using a limited buffer will have the same effect but the way tX currently does it is like the good ole trackers did it: it loads the samples COMPLETELY in RAM so there is no disk-activity at all while playing.... > >- With 6 to 8 tables playing my system is pretty loaded in these cases > >it might be a performance win to have the samples in the memory > >already.. (well these are just assumptions - we should get your code > >applied to the new stuff to see whether it's true...) >=20 > benno's code makes sure it *is* in RAM already. just not all of it > at one time. Yeah, you are right. I guess what I wanted to say was: If you mmap() files instead of loading there's a lot of other stuff happening aside for audio-rendering (you know like mmap()-code, fs-code, ide-code...) Now if you have a lot of turntables and some effects enabled your CPU may be pretty busy getting the audio ready for playback and that additional code may be too much.. well still: it's just an assumption ;) Bye, Alex --=20 _______________________________________________________________________ Alexander K=F6nig - alex@42.fht-esslingen.de http://termX.cjb.net [From the Homer Quotables:] =20 I'll work from midnight to eight, come home, sleep for five minutes, eat breakfast, sleep six more minutes, shower, then I have ten minutes to bask in Lisa's love, then I'm off to the power plant fresh as a daisy. -- Homer Simpson Lisa's Pony