Sylwester, Devin,
Thank you.
On Wed, Jan 8, 2014 at 1:19 PM, Sylwester Nawrocki
<sylvester.nawrocki@xxxxxxxxx> wrote:
> On 01/08/2014 08:15 PM, m silverstri wrote:
>>
>> Thanks.
>>
>> I am studying android source code.
>> From here, it has code which open("/dev/video11", O_RDWR, 0) as
>> decoding device.
>>
>>
>> http://androidxref.com/4.4.2_r1/xref/hardware/samsung_slsi/exynos5/libhwjpeg/ExynosJpegBase.cpp
>
>
> What you're looking for might be this proprietary Samsung JPEG codec driver
> used in Android.
>
> https://android.googlesource.com/kernel/exynos/+/android-exynos-3.4/drivers/media/video/exynos/jpeg/
>
> If you intend to use mainline kernel you need to consider the s5p-jpeg
> driver,
> which exposes to user space standard interface without any proprietary
> additions
> incompatible with the V4L2 spec.
>
>
>> I want to find out which is the corresponding driver code for device
>> '/dev/video11'.
>
>
> I suspect these numbers are fixed in the Android kernel (they are hard
> coded in the user space library as you're pointing out above), which is
> a pretty bad practice.
>
> It's better to use VIDIOC_QUERYCAP ioctl to find a video device with
> specific name, as Devin suggested. You can also find a video device
> exposed by a specific driver through sysfs, as is done in
> exynos_v4l2_open_devname() function in this a bit less hacky code:
>
> https://android.googlesource.com/platform/hardware/samsung_slsi/exynos5/+/jb-mr1-release/libv4l2/exynos_v4l2.c
>
> Thanks,
> Sylwester
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