On Mon, 05 Mar 2012 09:33:18 +0100 Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > I guess that motion is using the JPG compressed frames rather then > the i420 like special format these cameras also support, and it looks > like we don't reserve enoug space to buffer these frames. To fix this > we need to enlarge the size we reserve per frame in the sn9c20x driver, > edit sn9c20x.c and search for vga_mode, in that table you will > find a factor "4 / 8" (its in there 3 times), change all 3 occurences > to "5 / 8" and try again, then "6 / 8", etc. > > Normally I would be suspicious about SOF / EOF detection when we > need such a factor, but the timestamps in your log exactly match 30 > fps, so that seems to be fine. And in my experience with the USB bandwidth > stuff the sn9c20x does seem to compress less then other JPG cams, so > it makes sense that it needs bigger buffers to store the frames too. Hi Hans, The JPEG compression quality of the sn9c20x is 95%. That's why the frames are so big. Then, if the quality is not settable, I wonder why to use the JPEG format. BTW, I wonder also about the SN9C20X_I420: this format asks for a buffer greater than the native image. So, as these webcams are USB 2.0, shouldn't it be simpler to have only Bayer in the driver? -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
