* Laurent Pinchart | 2011-08-01 16:04:55 [+0200]: >> IIUC, there's no way to avoid copying the data since it has to >> processed before getting sent to userspace. > >Every UVC packet starts with a header that needs to be removed, so we >unfortunately can't get rid of all memcpy() calls. So we have something like that: +---------------+------------+-----------+ | hdr-to-remove | jpeg header| jpeg-data | +---------------+------------+-----------+ is it possible that you move the jpeg header to the front and tell it that it is larger than it reall is? Or change the data offset point to jpeg-data if there is one. Have no clue about the data format but a lot of file formats have something like "size of header" field or an offset to data fields within file. So if you can alter them you would get: +-------------+--------------+-----------+ | jpeg-header | jpeg hdr ign | jpeg-data | +-------------+--------------+-----------+ So you could move just the header alter it somehow so userland would skip to the correct data and you could avoid the large memcpy. Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
