* [PATCH 1/2] media: uapi: h264: clarify dec_ref_pic_marking_bit_size fields
@ 2019-09-05 13:12 Philipp Zabel
2019-09-05 13:12 ` [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field Philipp Zabel
0 siblings, 1 reply; 5+ messages in thread
From: Philipp Zabel @ 2019-09-05 13:12 UTC (permalink / raw)
To: linux-media
Cc: Tomasz Figa, Hans Verkuil, Paul Kocialkowski, Ezequiel Garcia,
Boris Brezillon, kernel
Since dec_ref_pic_marking_bit_size is not a syntax element
itself, explicitly state that this is the size in bits of
the dec_ref_pic_marking() syntax element contained in the
slice.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
index b9834625a939..c281bc7ed1b3 100644
--- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
+++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
@@ -1796,7 +1796,7 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
-
* - __u32
- ``dec_ref_pic_marking_bit_size``
- -
+ - Size in bits of the dec_ref_pic_marking() syntax element.
* - __u32
- ``pic_order_cnt_bit_size``
-
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field
2019-09-05 13:12 [PATCH 1/2] media: uapi: h264: clarify dec_ref_pic_marking_bit_size fields Philipp Zabel
@ 2019-09-05 13:12 ` Philipp Zabel
2019-09-26 13:23 ` Hans Verkuil
0 siblings, 1 reply; 5+ messages in thread
From: Philipp Zabel @ 2019-09-05 13:12 UTC (permalink / raw)
To: linux-media
Cc: Tomasz Figa, Hans Verkuil, Paul Kocialkowski, Ezequiel Garcia,
Boris Brezillon, kernel
Since pic_order_cnt_bit_size is not a syntax element itself, explicitly
state that it is the total size in bits of the pic_order_cnt_lsb,
delta_pic_order_cnt_bottom, delta_pic_order_cnt[0], and
delta_pic_order_cnt[1] syntax elements contained in the slice.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
index c281bc7ed1b3..08b49b2bbfa8 100644
--- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
+++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
@@ -1799,7 +1799,8 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
- Size in bits of the dec_ref_pic_marking() syntax element.
* - __u32
- ``pic_order_cnt_bit_size``
- -
+ - Size in bits of the pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
+ delta_pic_order_cnt[0], and delta_pic_order_cnt[1] syntax elements.
* - __u8
- ``cabac_init_idc``
-
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field
2019-09-05 13:12 ` [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field Philipp Zabel
@ 2019-09-26 13:23 ` Hans Verkuil
2019-09-26 14:09 ` Philipp Zabel
0 siblings, 1 reply; 5+ messages in thread
From: Hans Verkuil @ 2019-09-26 13:23 UTC (permalink / raw)
To: Philipp Zabel, linux-media
Cc: Tomasz Figa, Paul Kocialkowski, Ezequiel Garcia, Boris Brezillon, kernel
On 9/5/19 3:12 PM, Philipp Zabel wrote:
> Since pic_order_cnt_bit_size is not a syntax element itself, explicitly
> state that it is the total size in bits of the pic_order_cnt_lsb,
> delta_pic_order_cnt_bottom, delta_pic_order_cnt[0], and
> delta_pic_order_cnt[1] syntax elements contained in the slice.
>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
> Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> index c281bc7ed1b3..08b49b2bbfa8 100644
> --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> @@ -1799,7 +1799,8 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> - Size in bits of the dec_ref_pic_marking() syntax element.
> * - __u32
> - ``pic_order_cnt_bit_size``
> - -
> + - Size in bits of the pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
> + delta_pic_order_cnt[0], and delta_pic_order_cnt[1] syntax elements.
It's a little bit ambiguous: this field contains the size in bits of all these
fields combined, right? Not the size in bits of each field separately.
I.e. if these fields are all 8 bits, then pic_order_cnt_bit_size is 4*8 and
not just 8.
I think this should be rephrased.
Regards,
Hans
> * - __u8
> - ``cabac_init_idc``
> -
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field
2019-09-26 13:23 ` Hans Verkuil
@ 2019-09-26 14:09 ` Philipp Zabel
2019-09-26 14:16 ` Hans Verkuil
0 siblings, 1 reply; 5+ messages in thread
From: Philipp Zabel @ 2019-09-26 14:09 UTC (permalink / raw)
To: Hans Verkuil, linux-media
Cc: Tomasz Figa, Paul Kocialkowski, Ezequiel Garcia, Boris Brezillon, kernel
Hi Hans,
On Thu, 2019-09-26 at 15:23 +0200, Hans Verkuil wrote:
> On 9/5/19 3:12 PM, Philipp Zabel wrote:
> > Since pic_order_cnt_bit_size is not a syntax element itself, explicitly
> > state that it is the total size in bits of the pic_order_cnt_lsb,
> > delta_pic_order_cnt_bottom, delta_pic_order_cnt[0], and
> > delta_pic_order_cnt[1] syntax elements contained in the slice.
> >
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > ---
> > Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > index c281bc7ed1b3..08b49b2bbfa8 100644
> > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
> > @@ -1799,7 +1799,8 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> > - Size in bits of the dec_ref_pic_marking() syntax element.
> > * - __u32
> > - ``pic_order_cnt_bit_size``
> > - -
> > + - Size in bits of the pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
> > + delta_pic_order_cnt[0], and delta_pic_order_cnt[1] syntax elements.
>
> It's a little bit ambiguous: this field contains the size in bits of all these
> fields combined, right? Not the size in bits of each field separately.
Yes.
> I.e. if these fields are all 8 bits, then pic_order_cnt_bit_size is 4*8 and
> not just 8.
The size of pic_order_cnt_lsb is determined by another field's value
(log2_max_pic_order_cnt_lsb_minus4), and the other three are
exponential-Golomb coded, so each can be of different length (including
zero).
> I think this should be rephrased.
Ok, how about:
"Combined size in bits of the picture order count related syntax
elements: pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
delta_pic_order_cnt[0], and delta_pic_order_cnt[1]."
Actually, there's either pic_order_cnt_lsb + (optionally)
delta_pic_order_cnt_bottom present, or delta_pic_order_cnt[0] +
(optionally) delta_pic_order_cnt[1], never all four. Describing that in
the uapi docs seemed overly verbose, though. The relevant part in the
slice_header() syntax spec looks like this:
if (pic_order_cnt_type == 0) {
pic_order_cnt_lsb
if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag)
delta_pic_order_cnt_bottom
}
if (pic_order_cnt_type == 1 && !delta_pic_order_always_zero_flag) {
delta_pic_order_cnt[0]
if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag)
delta_pic_order_cnt[1]
}
pic_order_cnt_bit_size is supposed to be the size in bits of this whole
block. pic_order_cnt_type and log2_max_pic_order_cnt_lsb_minus4 are from
the SPS header, bottom_field_pic_order_in_frame_present_flag is from the
PPS header, and field_pic_flag is contained earlier in the slice header.
regards
Philipp
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] media: uapi: h264: clarify pic_order_cnt_bit_size field
2019-09-26 14:09 ` Philipp Zabel
@ 2019-09-26 14:16 ` Hans Verkuil
0 siblings, 0 replies; 5+ messages in thread
From: Hans Verkuil @ 2019-09-26 14:16 UTC (permalink / raw)
To: Philipp Zabel, linux-media
Cc: Tomasz Figa, Paul Kocialkowski, Ezequiel Garcia, Boris Brezillon, kernel
On 9/26/19 4:09 PM, Philipp Zabel wrote:
> Hi Hans,
>
> On Thu, 2019-09-26 at 15:23 +0200, Hans Verkuil wrote:
>> On 9/5/19 3:12 PM, Philipp Zabel wrote:
>>> Since pic_order_cnt_bit_size is not a syntax element itself, explicitly
>>> state that it is the total size in bits of the pic_order_cnt_lsb,
>>> delta_pic_order_cnt_bottom, delta_pic_order_cnt[0], and
>>> delta_pic_order_cnt[1] syntax elements contained in the slice.
>>>
>>> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
>>> ---
>>> Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>>> index c281bc7ed1b3..08b49b2bbfa8 100644
>>> --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>>> +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst
>>> @@ -1799,7 +1799,8 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
>>> - Size in bits of the dec_ref_pic_marking() syntax element.
>>> * - __u32
>>> - ``pic_order_cnt_bit_size``
>>> - -
>>> + - Size in bits of the pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
>>> + delta_pic_order_cnt[0], and delta_pic_order_cnt[1] syntax elements.
>>
>> It's a little bit ambiguous: this field contains the size in bits of all these
>> fields combined, right? Not the size in bits of each field separately.
>
> Yes.
>
>> I.e. if these fields are all 8 bits, then pic_order_cnt_bit_size is 4*8 and
>> not just 8.
>
> The size of pic_order_cnt_lsb is determined by another field's value
> (log2_max_pic_order_cnt_lsb_minus4), and the other three are
> exponential-Golomb coded, so each can be of different length (including
> zero).
>
>> I think this should be rephrased.
>
> Ok, how about:
>
> "Combined size in bits of the picture order count related syntax
> elements: pic_order_cnt_lsb, delta_pic_order_cnt_bottom,
> delta_pic_order_cnt[0], and delta_pic_order_cnt[1]."
That's better.
>
> Actually, there's either pic_order_cnt_lsb + (optionally)
> delta_pic_order_cnt_bottom present, or delta_pic_order_cnt[0] +
> (optionally) delta_pic_order_cnt[1], never all four. Describing that in
> the uapi docs seemed overly verbose, though.
I agree.
Regards,
Hans
The relevant part in the
> slice_header() syntax spec looks like this:
>
> if (pic_order_cnt_type == 0) {
> pic_order_cnt_lsb
> if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag)
> delta_pic_order_cnt_bottom
> }
> if (pic_order_cnt_type == 1 && !delta_pic_order_always_zero_flag) {
> delta_pic_order_cnt[0]
> if (bottom_field_pic_order_in_frame_present_flag && !field_pic_flag)
> delta_pic_order_cnt[1]
> }
>
> pic_order_cnt_bit_size is supposed to be the size in bits of this whole
> block. pic_order_cnt_type and log2_max_pic_order_cnt_lsb_minus4 are from
> the SPS header, bottom_field_pic_order_in_frame_present_flag is from the
> PPS header, and field_pic_flag is contained earlier in the slice header.
>
> regards
> Philipp
>
^ permalink raw reply [flat|nested] 5+ messages in thread
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