| Message ID | 20190116123701.10344-1-stanimir.varbanov@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | [RFC] media/doc: Allow sizeimage to be set by v4l clients | expand |
Hi Hans, On 1/18/19 11:13 AM, Hans Verkuil wrote: > On 1/16/19 1:37 PM, Stanimir Varbanov wrote: >> This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage >> field description to allow v4l clients to set bigger image size >> in case of variable length compressed data. >> >> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org> >> --- >> Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst | 5 ++++- >> Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 3 ++- >> 2 files changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >> index 7f82dad9013a..dbe0b74e9ba4 100644 >> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >> @@ -30,7 +30,10 @@ describing all planes of that format. >> >> * - __u32 >> - ``sizeimage`` >> - - Maximum size in bytes required for image data in this plane. >> + - Maximum size in bytes required for image data in this plane, >> + set by the driver. When the image consists of variable length >> + compressed data this is the maximum number of bytes required >> + to hold an image, and it is allowed to be set by the client. >> * - __u32 >> - ``bytesperline`` >> - Distance in bytes between the leftmost pixels in two adjacent >> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >> index 71eebfc6d853..54b6d2b67bd7 100644 >> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >> @@ -89,7 +89,8 @@ Single-planar format structure >> - Size in bytes of the buffer to hold a complete image, set by the >> driver. Usually this is ``bytesperline`` times ``height``. When >> the image consists of variable length compressed data this is the >> - maximum number of bytes required to hold an image. >> + maximum number of bytes required to hold an image, and it is >> + allowed to be set by the client. >> * - __u32 >> - ``colorspace`` >> - Image colorspace, from enum :c:type:`v4l2_colorspace`. >> > > Hmm. "maximum number of bytes required to hold an image": that's not actually true > for bitstream formats like MPEG. It's just the size of the buffer used to store the > bitstream, i.e. one buffer may actually contain multiple compressed images, or a > compressed image is split over multiple buffers. > Do you want me to change something in the current documentation, i.e. the quoted above? > Only for MJPEG is this statement true since each buffer will contain a single > compressed JPEG image. > > Regards, > > Hans > -- regards, Stan
On 4/10/19 5:39 PM, Hans Verkuil wrote: > On 4/10/19 4:21 PM, Stanimir Varbanov wrote: >> Hi Hans, >> >> On 3/14/19 3:11 PM, Hans Verkuil wrote: >>> On 1/21/19 11:48 AM, Stanimir Varbanov wrote: >>>> Hi Hans, >>>> >>>> On 1/18/19 11:13 AM, Hans Verkuil wrote: >>>>> On 1/16/19 1:37 PM, Stanimir Varbanov wrote: >>>>>> This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage >>>>>> field description to allow v4l clients to set bigger image size >>>>>> in case of variable length compressed data. >>>>>> >>>>>> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org> >>>>>> --- >>>>>> Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst | 5 ++++- >>>>>> Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 3 ++- >>>>>> 2 files changed, 6 insertions(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >>>>>> index 7f82dad9013a..dbe0b74e9ba4 100644 >>>>>> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >>>>>> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst >>>>>> @@ -30,7 +30,10 @@ describing all planes of that format. >>>>>> >>>>>> * - __u32 >>>>>> - ``sizeimage`` >>>>>> - - Maximum size in bytes required for image data in this plane. >>>>>> + - Maximum size in bytes required for image data in this plane, >>>>>> + set by the driver. When the image consists of variable length >>>>>> + compressed data this is the maximum number of bytes required >>>>>> + to hold an image, and it is allowed to be set by the client. >>>>>> * - __u32 >>>>>> - ``bytesperline`` >>>>>> - Distance in bytes between the leftmost pixels in two adjacent >>>>>> diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >>>>>> index 71eebfc6d853..54b6d2b67bd7 100644 >>>>>> --- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >>>>>> +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst >>>>>> @@ -89,7 +89,8 @@ Single-planar format structure >>>>>> - Size in bytes of the buffer to hold a complete image, set by the >>>>>> driver. Usually this is ``bytesperline`` times ``height``. When >>>>>> the image consists of variable length compressed data this is the >>>>>> - maximum number of bytes required to hold an image. >>>>>> + maximum number of bytes required to hold an image, and it is >>>>>> + allowed to be set by the client. >>>>>> * - __u32 >>>>>> - ``colorspace`` >>>>>> - Image colorspace, from enum :c:type:`v4l2_colorspace`. >>>>>> >>>>> >>>>> Hmm. "maximum number of bytes required to hold an image": that's not actually true >>>>> for bitstream formats like MPEG. It's just the size of the buffer used to store the >>>>> bitstream, i.e. one buffer may actually contain multiple compressed images, or a >>>>> compressed image is split over multiple buffers. >>>>> >>>> >>>> Do you want me to change something in the current documentation, i.e. >>>> the quoted above? >>> >>> Hmm, it looks like this discussion stalled (i.e. I forgot to reply). >>> >>> How about this: >>> >>> "When the image consists of variable length compressed data this is the >>> number of bytes required by the encoder to support the worst-case >> >> I don't think 'encoder' is the right word here: >> >> s/encoder/encoder or decoder > > or perhaps just 'codec'? Either is fine by me. OK, then just 'codec'. > >> >>> compression scenario. Clients are allowed to set this field. However, >>> drivers may ignore the value or modify it." >> >> Can we rephrase to: >> >> "Clients are allowed to set sizeimage field, but however drivers my >> ignore the value or modify it." >> > > How about this: > > "Clients are allowed to set the sizeimage field, but drivers may > modify it." I'm fine with that. I'll send with those changes and as regular patch. Thanks! > > 'ignore the value' isn't right, since that suggests that the sizeimage > value that is returned may not be in actual use. Since sizeimage can now > be set by userspace, this means that a sanity check is needed in drivers > as well (i.e. what if userspace sets sizeimage to ~0?) > > This should be tested in v4l2-compliance as well. > > Regards, > > Hans > -- regards, Stan
diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst index 7f82dad9013a..dbe0b74e9ba4 100644 --- a/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst @@ -30,7 +30,10 @@ describing all planes of that format. * - __u32 - ``sizeimage`` - - Maximum size in bytes required for image data in this plane. + - Maximum size in bytes required for image data in this plane, + set by the driver. When the image consists of variable length + compressed data this is the maximum number of bytes required + to hold an image, and it is allowed to be set by the client. * - __u32 - ``bytesperline`` - Distance in bytes between the leftmost pixels in two adjacent diff --git a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst index 71eebfc6d853..54b6d2b67bd7 100644 --- a/Documentation/media/uapi/v4l/pixfmt-v4l2.rst +++ b/Documentation/media/uapi/v4l/pixfmt-v4l2.rst @@ -89,7 +89,8 @@ Single-planar format structure - Size in bytes of the buffer to hold a complete image, set by the driver. Usually this is ``bytesperline`` times ``height``. When the image consists of variable length compressed data this is the - maximum number of bytes required to hold an image. + maximum number of bytes required to hold an image, and it is + allowed to be set by the client. * - __u32 - ``colorspace`` - Image colorspace, from enum :c:type:`v4l2_colorspace`.
This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage field description to allow v4l clients to set bigger image size in case of variable length compressed data. Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org> --- Documentation/media/uapi/v4l/pixfmt-v4l2-mplane.rst | 5 ++++- Documentation/media/uapi/v4l/pixfmt-v4l2.rst | 3 ++- 2 files changed, 6 insertions(+), 2 deletions(-) -- 2.17.1