Tuukka Toivonen <tuukkat@xxxxxxxxxx> writes: > No, it doesn't: > > while (true) > MCAPTURE(0) <- effectively null operation for driver > SYNC(0) <- driver converts internal buffer into mmap buffer > // application processes frame directly in mmap buffer, no memcpy > // * hardware will continue capturing into internal buffers! * > } That is true for *your* driver, because it does some double buffering which the application doesn't see. It is *not* true in general, thus applications can't depend on that. If you try this with bttv for example you will lose frames, because bttv doesn't have that kind of internal buffering. The v4l API should work the same way for all drivers and applications. And the MCAPTURE/SYNC ioctls (QBUF/DQBUF in v4l2) are designed to allow applications control the drivers buffering. Your driver should just support that instead of hiding the buffers. Gerd -- sigfault
