On Fri, 25 Dec 2009, TAXI wrote: > I tried a Medion MD 95700 with kernel 2.6.32 (for tests: 2.6.30.9) and > have a very bad image and sound quality. I have two of these boxes, and they work great -- but I've had to patch the kernel in different ways to have success. One way for my production machine happily running 2.6.14 with patches, due to the fact that this kernel has a problem with isochronous data being passed through an external hub -- the 95700 has a built-in hub to allow its built-in USB port to co- exist with the datastream and the remote control. The other way works for newer kernels, sort of, and looks for the data on a different alternate interface where it can be found (but it requires a kick in the pants to get it started), although it is possible to successfully use either the isochronous or the bulk datastream which the device delivers with these later modern kernels. The other thing to note is that this device delivers a full unfiltered Transport Stream, which with the 13,27Mbit/sec typical bandwidth per channel used in your country (apart from some local exceptions of greater values), will require a USB2 interface. I mention this because the last multi-gigahertz-CPU machine I got my grubby fingers on still had only a built-in USB1 chipset, although when you write: > under windows XP the image and sound is perfect. That leads me to believe you have a USB2 interface and can ignore this -- although if you're somehow failing to load the EHCI driver and falling back to the companion UHCI or EHCI USB1, it will be a problem. You may want to verify that -- I am thwarted by unco-operative hardware that prevents me from using numbered kernel revisions as you mention as opposed to my custom kernels direct from the `git' repository tuned to my hardware and usually with more patches and hacks than are reasonable. > [mpeg2video @ 0xc62be0]ac-tex damaged at 23 4 > [mpeg2video @ 0xc62be0]ac-tex damaged at 14 9 > [mpeg2video @ 0xc62be0]skipped MB in I frame at 40 10 > [mpeg2video @ 0xc62be0]invalid mb type in I Frame at 29 15 > [mpeg2video @ 0xc62be0]skipped MB in I frame at 32 19 This and the following errors can be caused by any number of reasons for a corrupt data stream -- inadequate bandwidth (use of USB1 where USB2 is required for a complete Transport Stream), improper antenna orientation, or, with certain kernel revisions, attempting to read an isochronous data stream as bulk or vice versa. Ooops, I just rebooted after a crash before plugging in a more- than-one-button-mouse on this machine I never intended to make serious use of, so I can't paste the diffs, but... around line 620 in my reference code, there is a line that sets the alternate interface to 6. This is expected to be bulk, but on my boxes is isoc. You can change this to interface 0, on which my boxes delivers bulk data flawlessly. I've attempted to add a test of what sort of data is present on this interface, and if it's not bulk, decides to read isoc data from this interface (6) instead. That also works, but somehow needs an extra kick such that the first time it fails, yet is fine after that. (I get occasional failures from other tuner cards that work fine immediately after, so I've worked around this in the scripts I use.) Anyway, I've been meaning to clean up this patch, or the alternative patches, and submit them to be ignored, but when I have my machine operating fully again (yeahright), I can send you some of these alternative patches to try -- running successfully on 2.6.14 and 2.6.27-rc4. Hope this is helpful in spite of its vagueness... thanks barry bouwsma -- 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
