On Wed, Oct 18, 2023 at 9:09 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > On 18/10/2023 14:52, Shengjiu Wang wrote: > > On Wed, Oct 18, 2023 at 3:58 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >> > >> On 18/10/2023 09:40, Shengjiu Wang wrote: > >>> On Wed, Oct 18, 2023 at 3:31 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >>>> > >>>> On 18/10/2023 09:23, Shengjiu Wang wrote: > >>>>> On Wed, Oct 18, 2023 at 10:27 AM Shengjiu Wang <shengjiu.wang@xxxxxxxxx> wrote: > >>>>>> > >>>>>> On Tue, Oct 17, 2023 at 9:37 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >>>>>>> > >>>>>>> On 17/10/2023 15:11, Shengjiu Wang wrote: > >>>>>>>> On Mon, Oct 16, 2023 at 9:16 PM Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > >>>>>>>>> > >>>>>>>>> Hi Shengjiu, > >>>>>>>>> > >>>>>>>>> On 13/10/2023 10:31, Shengjiu Wang wrote: > >>>>>>>>>> Fixed point controls are used by the user to configure > >>>>>>>>>> the audio sample rate to driver. > >>>>>>>>>> > >>>>>>>>>> Add V4L2_CID_ASRC_SOURCE_RATE and V4L2_CID_ASRC_DEST_RATE > >>>>>>>>>> new IDs for ASRC rate control. > >>>>>>>>>> > >>>>>>>>>> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx> > >>>>>>>>>> --- > >>>>>>>>>> .../userspace-api/media/v4l/common.rst | 1 + > >>>>>>>>>> .../media/v4l/ext-ctrls-fixed-point.rst | 36 +++++++++++++++++++ > >>>>>>>>>> .../media/v4l/vidioc-g-ext-ctrls.rst | 4 +++ > >>>>>>>>>> .../media/v4l/vidioc-queryctrl.rst | 7 ++++ > >>>>>>>>>> .../media/videodev2.h.rst.exceptions | 1 + > >>>>>>>>>> drivers/media/v4l2-core/v4l2-ctrls-core.c | 5 +++ > >>>>>>>>>> drivers/media/v4l2-core/v4l2-ctrls-defs.c | 4 +++ > >>>>>>>>>> include/media/v4l2-ctrls.h | 2 ++ > >>>>>>>>>> include/uapi/linux/v4l2-controls.h | 13 +++++++ > >>>>>>>>>> include/uapi/linux/videodev2.h | 3 ++ > >>>>>>>>>> 10 files changed, 76 insertions(+) > >>>>>>>>>> create mode 100644 Documentation/userspace-api/media/v4l/ext-ctrls-fixed-point.rst > >>>>>>>>>> > >>>>>>>>>> diff --git a/Documentation/userspace-api/media/v4l/common.rst b/Documentation/userspace-api/media/v4l/common.rst > >>>>>>>>>> index ea0435182e44..35707edffb13 100644 > >>>>>>>>>> --- a/Documentation/userspace-api/media/v4l/common.rst > >>>>>>>>>> +++ b/Documentation/userspace-api/media/v4l/common.rst > >>>>>>>>>> @@ -52,6 +52,7 @@ applicable to all devices. > >>>>>>>>>> ext-ctrls-fm-rx > >>>>>>>>>> ext-ctrls-detect > >>>>>>>>>> ext-ctrls-colorimetry > >>>>>>>>>> + ext-ctrls-fixed-point > >>>>>>>>> > >>>>>>>>> Rename this to ext-ctrls-audio-m2m. > >>>>>>>>> > >>>>>>>>>> fourcc > >>>>>>>>>> format > >>>>>>>>>> planar-apis > >>>>>>>>>> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-fixed-point.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-fixed-point.rst > >>>>>>>>>> new file mode 100644 > >>>>>>>>>> index 000000000000..2ef6e250580c > >>>>>>>>>> --- /dev/null > >>>>>>>>>> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-fixed-point.rst > >>>>>>>>>> @@ -0,0 +1,36 @@ > >>>>>>>>>> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later > >>>>>>>>>> + > >>>>>>>>>> +.. _fixed-point-controls: > >>>>>>>>>> + > >>>>>>>>>> +*************************** > >>>>>>>>>> +Fixed Point Control Reference > >>>>>>>>> > >>>>>>>>> This is for audio controls. "Fixed Point" is just the type, and it doesn't make > >>>>>>>>> sense to group fixed point controls. But it does make sense to group the audio > >>>>>>>>> controls. > >>>>>>>>> > >>>>>>>>> V4L2 controls can be grouped into classes. Basically it is a way to put controls > >>>>>>>>> into categories, and for each category there is also a control that gives a > >>>>>>>>> description of the class (see 2.15.15 in > >>>>>>>>> https://linuxtv.org/downloads/v4l-dvb-apis-new/driver-api/v4l2-controls.html#introduction) > >>>>>>>>> > >>>>>>>>> If you use e.g. 'v4l2-ctl -l' to list all the controls, then you will see that > >>>>>>>>> they are grouped based on what class of control they are. > >>>>>>>>> > >>>>>>>>> So I think it would be a good idea to create a new control class for M2M audio controls, > >>>>>>>>> instead of just adding them to the catch-all 'User Controls' class. > >>>>>>>>> > >>>>>>>>> Search e.g. for V4L2_CTRL_CLASS_COLORIMETRY and V4L2_CID_COLORIMETRY_CLASS to see how > >>>>>>>>> it is done. > >>>>>>>>> > >>>>>>>>> M2M_AUDIO would probably be a good name for the class. > >>>>>>>>> > >>>>>>>>>> +*************************** > >>>>>>>>>> + > >>>>>>>>>> +These controls are intended to support an asynchronous sample > >>>>>>>>>> +rate converter. > >>>>>>>>> > >>>>>>>>> Add ' (ASRC).' at the end to indicate the common abbreviation for > >>>>>>>>> that. > >>>>>>>>> > >>>>>>>>>> + > >>>>>>>>>> +.. _v4l2-audio-asrc: > >>>>>>>>>> + > >>>>>>>>>> +``V4L2_CID_ASRC_SOURCE_RATE`` > >>>>>>>>>> + sets the resampler source rate. > >>>>>>>>>> + > >>>>>>>>>> +``V4L2_CID_ASRC_DEST_RATE`` > >>>>>>>>>> + sets the resampler destination rate. > >>>>>>>>> > >>>>>>>>> Document the unit (Hz) for these two controls. > >>>>>>>>> > >>>>>>>>>> + > >>>>>>>>>> +.. c:type:: v4l2_ctrl_fixed_point > >>>>>>>>>> + > >>>>>>>>>> +.. cssclass:: longtable > >>>>>>>>>> + > >>>>>>>>>> +.. tabularcolumns:: |p{1.5cm}|p{5.8cm}|p{10.0cm}| > >>>>>>>>>> + > >>>>>>>>>> +.. flat-table:: struct v4l2_ctrl_fixed_point > >>>>>>>>>> + :header-rows: 0 > >>>>>>>>>> + :stub-columns: 0 > >>>>>>>>>> + :widths: 1 1 2 > >>>>>>>>>> + > >>>>>>>>>> + * - __u32 > >>>>>>>>> > >>>>>>>>> Hmm, shouldn't this be __s32? > >>>>>>>>> > >>>>>>>>>> + - ``integer`` > >>>>>>>>>> + - integer part of fixed point value. > >>>>>>>>>> + * - __s32 > >>>>>>>>> > >>>>>>>>> and this __u32? > >>>>>>>>> > >>>>>>>>> You want to be able to use this generic type as a signed value. > >>>>>>>>> > >>>>>>>>>> + - ``fractional`` > >>>>>>>>>> + - fractional part of fixed point value, which is Q31. > >>>>>>>>>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst > >>>>>>>>>> index f9f73530a6be..1811dabf5c74 100644 > >>>>>>>>>> --- a/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst > >>>>>>>>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-g-ext-ctrls.rst > >>>>>>>>>> @@ -295,6 +295,10 @@ still cause this situation. > >>>>>>>>>> - ``p_av1_film_grain`` > >>>>>>>>>> - A pointer to a struct :c:type:`v4l2_ctrl_av1_film_grain`. Valid if this control is > >>>>>>>>>> of type ``V4L2_CTRL_TYPE_AV1_FILM_GRAIN``. > >>>>>>>>>> + * - struct :c:type:`v4l2_ctrl_fixed_point` * > >>>>>>>>>> + - ``p_fixed_point`` > >>>>>>>>>> + - A pointer to a struct :c:type:`v4l2_ctrl_fixed_point`. Valid if this control is > >>>>>>>>>> + of type ``V4L2_CTRL_TYPE_FIXED_POINT``. > >>>>>>>>>> * - void * > >>>>>>>>>> - ``ptr`` > >>>>>>>>>> - A pointer to a compound type which can be an N-dimensional array > >>>>>>>>>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst > >>>>>>>>>> index 4d38acafe8e1..9285f4f39eed 100644 > >>>>>>>>>> --- a/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst > >>>>>>>>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-queryctrl.rst > >>>>>>>>>> @@ -549,6 +549,13 @@ See also the examples in :ref:`control`. > >>>>>>>>>> - n/a > >>>>>>>>>> - A struct :c:type:`v4l2_ctrl_av1_film_grain`, containing AV1 Film Grain > >>>>>>>>>> parameters for stateless video decoders. > >>>>>>>>>> + * - ``V4L2_CTRL_TYPE_FIXED_POINT`` > >>>>>>>>>> + - n/a > >>>>>>>>>> + - n/a > >>>>>>>>>> + - n/a > >>>>>>>>>> + - A struct :c:type:`v4l2_ctrl_fixed_point`, containing parameter which has > >>>>>>>>>> + integer part and fractional part, i.e. audio sample rate. > >>>>>>>>>> + > >>>>>>>>>> > >>>>>>>>>> .. raw:: latex > >>>>>>>>>> > >>>>>>>>>> diff --git a/Documentation/userspace-api/media/videodev2.h.rst.exceptions b/Documentation/userspace-api/media/videodev2.h.rst.exceptions > >>>>>>>>>> index e61152bb80d1..2faa5a2015eb 100644 > >>>>>>>>>> --- a/Documentation/userspace-api/media/videodev2.h.rst.exceptions > >>>>>>>>>> +++ b/Documentation/userspace-api/media/videodev2.h.rst.exceptions > >>>>>>>>>> @@ -167,6 +167,7 @@ replace symbol V4L2_CTRL_TYPE_AV1_SEQUENCE :c:type:`v4l2_ctrl_type` > >>>>>>>>>> replace symbol V4L2_CTRL_TYPE_AV1_TILE_GROUP_ENTRY :c:type:`v4l2_ctrl_type` > >>>>>>>>>> replace symbol V4L2_CTRL_TYPE_AV1_FRAME :c:type:`v4l2_ctrl_type` > >>>>>>>>>> replace symbol V4L2_CTRL_TYPE_AV1_FILM_GRAIN :c:type:`v4l2_ctrl_type` > >>>>>>>>>> +replace symbol V4L2_CTRL_TYPE_FIXED_POINT :c:type:`v4l2_ctrl_type` > >>>>>>>>>> > >>>>>>>>>> # V4L2 capability defines > >>>>>>>>>> replace define V4L2_CAP_VIDEO_CAPTURE device-capabilities > >>>>>>>>>> diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c > >>>>>>>>>> index a662fb60f73f..7a616ac91059 100644 > >>>>>>>>>> --- a/drivers/media/v4l2-core/v4l2-ctrls-core.c > >>>>>>>>>> +++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c > >>>>>>>>>> @@ -1168,6 +1168,8 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx, > >>>>>>>>>> if (!area->width || !area->height) > >>>>>>>>>> return -EINVAL; > >>>>>>>>>> break; > >>>>>>>>>> + case V4L2_CTRL_TYPE_FIXED_POINT: > >>>>>>>>>> + break; > >>>>>>>>> > >>>>>>>>> Hmm, this would need this patch 'v4l2-ctrls: add support for V4L2_CTRL_WHICH_MIN/MAX_VAL': > >>>>>>>>> > >>>>>>>>> https://patchwork.linuxtv.org/project/linux-media/patch/20231010022136.1504015-7-yunkec@xxxxxxxxxx/ > >>>>>>>>> > >>>>>>>>> since min and max values are perfectly fine for a fixed point value. > >>>>>>>>> > >>>>>>>>> Even a step value (currently not supported in that patch) would make sense. > >>>>>>>>> > >>>>>>>>> But I wonder if we couldn't simplify this: instead of creating a v4l2_ctrl_fixed_point, > >>>>>>>>> why not represent the fixed point value as a Q31.32. Then the standard > >>>>>>>>> minimum/maximum/step values can be used, and it acts like a regular V4L2_TYPE_INTEGER64. > >>>>>>>>> > >>>>>>>>> Except that both userspace and drivers need to multiply it with 2^-32 to get the actual > >>>>>>>>> value. > >>>>>>>>> > >>>>>>>>> So in enum v4l2_ctrl_type add: > >>>>>>>>> > >>>>>>>>> V4L2_CTRL_TYPE_FIXED_POINT = 10, > >>>>>>>>> > >>>>>>>>> (10, because it is no longer a compound type). > >>>>>>>> > >>>>>>>> Seems we don't need V4L2_CTRL_TYPE_FIXED_POINT, just use V4L2_TYPE_INTEGER64? > >>>>>>>> > >>>>>>>> The reason I use the 'integer' and 'fractional' is that I want > >>>>>>>> 'integer' to be the normal sample > >>>>>>>> rate, for example 48kHz. The 'fractional' is the difference with > >>>>>>>> normal sample rate. > >>>>>>>> > >>>>>>>> For example, the rate = 47998.12345. so integer = 48000, fractional= -1.87655. > >>>>>>>> > >>>>>>>> So if we use s64 for rate, then in driver need to convert the rate to > >>>>>>>> the closed normal > >>>>>>>> sample rate + fractional. > >>>>>>> > >>>>>>> That wasn't what the documentation said :-) > >>>>>>> > >>>>>>> So this is really two controls: one for the 'normal sample rate' (whatever 'normal' > >>>>>>> means in this context) and the offset to the actual sample rate. > >>>>>>> > >>>>>>> Presumably the 'normal' sample rate is set once, while the offset changes > >>>>>>> regularly. > >>>>>>> > >>>>>>> But why do you need the 'normal' sample rate? With audio resampling I assume > >>>>>>> you resample from one rate to another, so why do you need a third 'normal' > >>>>>>> rate? > >>>>>>> > >>>>>> > >>>>>> 'Normal' rate is used to select the prefilter table. > >>>>>> > >>>>> > >>>>> Currently I think we may define > >>>>> V4L2_CID_M2M_AUDIO_SOURCE_RATE > >>>>> V4L2_CID_M2M_AUDIO_DEST_RATE > >>>> > >>>> That makes sense. > >>>> > >>>>> V4L2_CID_M2M_AUDIO_ASRC_RATIO_MOD > >>>> > >>>> OK, can you document this control? Just write it down in the reply, I just want > >>>> to understand how the integer value you set here is used. > >>>> > >>> > >>> It is Q31 value. It is equal to: > >>> in_rate_new / out_rate_new - in_rate_old / out_rate_old > >> > >> So that's not an integer. Also, Q31 is limited to -1...1, and I think > >> that's too limiting. > >> > >> For this having a Q31.32 fixed point type still makes a lot of sense. > >> > >> I still feel this is a overly complicated API. > >> > >> See more below... > >> > >>> > >>> Best regards > >>> Wang shengjiu > >>> > >>>> Regards, > >>>> > >>>> Hans > >>>> > >>>>> > >>>>> All of them can be V4L2_CTRL_TYPE_INTEGER. > >>>>> > >>>>> RATIO_MOD was defined in the very beginning version. > >>>>> I think it is better to let users calculate this value. > >>>>> > >>>>> The reason is: > >>>>> if we define the offset for source rate and dest rate in > >>>>> driver separately, when offset of source rate is set, > >>>>> driver don't know if it needs to wait or not the dest rate > >>>>> offset, then go to calculate the ratio_mod. > >> > >> Ah, in order to update the ratio mod userspace needs to set both source and > >> dest rate at the same time to avoid race conditions. > >> > >> That is perfectly possible in the V4L2 control framework. See: > >> > >> https://linuxtv.org/downloads/v4l-dvb-apis-new/driver-api/v4l2-controls.html#control-clusters > >> > >> In practice, isn't it likely that you would fix either the source or > >> destination rate, and let the other rate fluctuate? It kind of feels weird > >> to me that both source AND destination rates can fluctuate over time. > >> > > Right, the source and dest rates needn't change in same time. > > > >> In any case, with a control cluster it doesn't really matter, you can set > >> one rate or both rates, and it will be handled atomically. > >> > >> I feel that the RATIO_MOD control is too hardware specific. This is something > >> that should be hidden in the driver. > >> > > > > I will use: > > > > V4L2_CID_M2M_AUDIO_SOURCE_RATE > > V4L2_CID_M2M_AUDIO_DEST_RATE > > V4L2_CID_M2M_AUDIO_SOURCE_RATE_OFFSET > > V4L2_CID_M2M_AUDIO_DEST_RATE_OFFSET > > > > 'OFFSET' is V4L2_CTRL_TYPE_FIXED_POINT, which is Q31.32. > > So now I come back to my original question: why do you need both > the rate and the offset? Isn't it enough to set just the rates, > as long as that is in fixed point format? > > Why does the driver need both the 'ideal' rate + the offset? > > I'm not opposed to this, I'm just trying to understand whether this > makes sense. > > Can't you take e.g. the source and dest rate as starting points > when you start streaming? And every time userspace updates one or both > of these rates you calculate the ratio_mod compared to the previous rates? > > Or is there a reason why you need the ideal rates as well? E.g. 48000 or > 44100, etc. > ideal rates is used to select prefilter table. the prefilter table is indexed by ideal rates. The asrc has two part: prefilter and resampler filter. The convert ratio is applied to rasampler filter part. best regards wang shengjiu
