Erik de Castro Lopo
2008-Feb-13 03:01 UTC
[ogg-dev] OggPCM: support for little-endianness only?
Ian Malone wrote:> This is all well and good but OggPCM is in an Ogg transport > stream, so that needs to be unpacked anyway.Fair enough. Since the ogg pages (which I beleive are 4k) need to be unpacked anyway, there is little harm in having to (possibly) do endswapping as well. Erik -- ----------------------------------------------------------------- Erik de Castro Lopo ----------------------------------------------------------------- "Yeah, all that emacs is missing to be counted as a full-featured operating system is an easy-to-use text editor." -- Arnold Krille on the Linux Audio Developer mailing list
On 2008-02-13, Erik de Castro Lopo wrote:>> This is all well and good but OggPCM is in an Ogg transport stream, >> so that needs to be unpacked anyway. > > Fair enough. Since the ogg pages (which I beleive are 4k) need to be > unpacked anyway, there is little harm in having to (possibly) do > endswapping as well.I don't want to be starting no holy wars here, but... Isn't the precise problem that mplayer people have with ogg in that the paging structure necessitates too much CPU intervention, instead of allowing braindead, direct, DMA, scatter/gather? If so, isn't it the case that the problem is in ogg, not in Erik's reasoning? -- Sampo Syreeni, aka decoy - mailto:decoy@iki.fi, tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
On 14/02/2008, Sampo Syreeni <decoy@iki.fi> wrote:> On 2008-02-13, Erik de Castro Lopo wrote: > > >> This is all well and good but OggPCM is in an Ogg transport stream, > >> so that needs to be unpacked anyway. > > > > Fair enough. Since the ogg pages (which I beleive are 4k) need to be > > unpacked anyway, there is little harm in having to (possibly) do > > endswapping as well. > > I don't want to be starting no holy wars here, but... Isn't the precise > problem that mplayer people have with ogg in that the paging structure > necessitates too much CPU intervention, instead of allowing braindead, > direct, DMA, scatter/gather? If so, isn't it the case that the problem > is in ogg, not in Erik's reasoning?yeah, totally. Erik's original argument was just about dealing with the endianness of PCM in general, and makes sense in the context of his libsndfile (which is most often used for formats where DMA is possible, like wav and aiff). K.