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Message-ID: <04dec113-f6d8-a9f8-0a8a-3279ff5fe870@xs4all.nl>
Date:   Mon, 3 Jul 2023 12:04:39 +0200
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Subject: Re: [PATCH 1/6] media: v4l2: Add audio capture and output support
Content-Language: en-US
To:     Shengjiu Wang <shengjiu.wang@gmail.com>,
        Sakari Ailus <sakari.ailus@iki.fi>
Cc:     Shengjiu Wang <shengjiu.wang@nxp.com>, tfiga@chromium.org,
        m.szyprowski@samsung.com, mchehab@kernel.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        Xiubo.Lee@gmail.com, festevam@gmail.com, nicoleotsuka@gmail.com,
        lgirdwood@gmail.com, broonie@kernel.org, perex@perex.cz,
        tiwai@suse.com, alsa-devel@alsa-project.org,
        linuxppc-dev@lists.ozlabs.org, Jacopo Mondi <jacopo@jmondi.org>
References: <1688002673-28493-1-git-send-email-shengjiu.wang@nxp.com>
 <1688002673-28493-2-git-send-email-shengjiu.wang@nxp.com>
 <ZJ6o5fT4V4HXivFa@valkosipuli.retiisi.eu>
 <CAA+D8AND1yZ7eZLjBGxVF=i3hLMecUm-j7AVHN9npJi-4=3VrA@mail.gmail.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
In-Reply-To: <CAA+D8AND1yZ7eZLjBGxVF=i3hLMecUm-j7AVHN9npJi-4=3VrA@mail.gmail.com>
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On 03/07/2023 11:54, Shengjiu Wang wrote:
> Hi Sakari
> 
> On Fri, Jun 30, 2023 at 6:05 PM Sakari Ailus <sakari.ailus@iki.fi <mailto:sakari.ailus@iki.fi>> wrote:
> 
>     Hi Shengjiu,
> 
>     On Thu, Jun 29, 2023 at 09:37:48AM +0800, Shengjiu Wang wrote:
>     > Audio signal processing has the requirement for memory to
>     > memory similar as Video.
>     >
>     > This patch is to add this support in v4l2 framework, defined
>     > new buffer type V4L2_BUF_TYPE_AUDIO_CAPTURE and
>     > V4L2_BUF_TYPE_AUDIO_OUTPUT, defined new format v4l2_audio_format
>     > for audio case usage.
> 
>     Why are you proposing to add this to V4L2 framework instead of doing this
>     within ALSA?
> 
>     Also cc Hans and Jacopo.
> 
> 
> There is no such memory to memory interface defined in ALSA.  Seems
> ALSA is not designed for M2M cases.
> 
> V4L2 is designed for video, radio, image, sdr, meta...,   so I think audio can be
> naturally added to the support scope.  

While I do not have an objection as such supporting this as part of V4L2, I do
want to know if the ALSA maintainers think it is OK as well before I am going
to spend time on this.

In principle the V4L2 mem2mem framework doesn't really care what type of data
is processed, it is just a matter of adding audio types (or reusing them from ALSA,
which is presumably the intention here).

Regards,

	Hans

> 
> Thanks.
>  
> Best regards
> Shengjiu Wang
> 
>      
> 
> 
>     >
>     > The created audio device is named "/dev/audioX".
>     >
>     > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com <mailto:shengjiu.wang@nxp.com>>
>     > ---
>     >  .../media/common/videobuf2/videobuf2-v4l2.c   |  4 ++
>     >  drivers/media/v4l2-core/v4l2-dev.c            | 17 ++++++
>     >  drivers/media/v4l2-core/v4l2-ioctl.c          | 52 +++++++++++++++++++
>     >  include/media/v4l2-dev.h                      |  2 +
>     >  include/media/v4l2-ioctl.h                    | 34 ++++++++++++
>     >  include/uapi/linux/videodev2.h                | 19 +++++++
>     >  6 files changed, 128 insertions(+)
>     >
>     > diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>     > index c7a54d82a55e..12f2be2773a2 100644
>     > --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
>     > +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>     > @@ -785,6 +785,10 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
>     >       case V4L2_BUF_TYPE_META_OUTPUT:
>     >               requested_sizes[0] = f->fmt.meta.buffersize;
>     >               break;
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             requested_sizes[0] = f->fmt.audio.buffersize;
>     > +             break;
>     >       default:
>     >               return -EINVAL;
>     >       }
>     > diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
>     > index f81279492682..67484f4c6eaf 100644
>     > --- a/drivers/media/v4l2-core/v4l2-dev.c
>     > +++ b/drivers/media/v4l2-core/v4l2-dev.c
>     > @@ -553,6 +553,7 @@ static void determine_valid_ioctls(struct video_device *vdev)
>     >       bool is_tch = vdev->vfl_type == VFL_TYPE_TOUCH;
>     >       bool is_meta = vdev->vfl_type == VFL_TYPE_VIDEO &&
>     >                      (vdev->device_caps & meta_caps);
>     > +     bool is_audio = vdev->vfl_type == VFL_TYPE_AUDIO;
>     >       bool is_rx = vdev->vfl_dir != VFL_DIR_TX;
>     >       bool is_tx = vdev->vfl_dir != VFL_DIR_RX;
>     >       bool is_io_mc = vdev->device_caps & V4L2_CAP_IO_MC;
>     > @@ -664,6 +665,19 @@ static void determine_valid_ioctls(struct video_device *vdev)
>     >               SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_meta_out);
>     >               SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_meta_out);
>     >       }
>     > +     if (is_audio && is_rx) {
>     > +             /* audio capture specific ioctls */
>     > +             SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_audio_cap);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_audio_cap);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_audio_cap);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_audio_cap);
>     > +     } else if (is_audio && is_tx) {
>     > +             /* audio output specific ioctls */
>     > +             SET_VALID_IOCTL(ops, VIDIOC_ENUM_FMT, vidioc_enum_fmt_audio_out);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_G_FMT, vidioc_g_fmt_audio_out);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_S_FMT, vidioc_s_fmt_audio_out);
>     > +             SET_VALID_IOCTL(ops, VIDIOC_TRY_FMT, vidioc_try_fmt_audio_out);
>     > +     }
>     >       if (is_vbi) {
>     >               /* vbi specific ioctls */
>     >               if ((is_rx && (ops->vidioc_g_fmt_vbi_cap ||
>     > @@ -927,6 +941,9 @@ int __video_register_device(struct video_device *vdev,
>     >       case VFL_TYPE_TOUCH:
>     >               name_base = "v4l-touch";
>     >               break;
>     > +     case VFL_TYPE_AUDIO:
>     > +             name_base = "audio";
>     > +             break;
>     >       default:
>     >               pr_err("%s called with unknown type: %d\n",
>     >                      __func__, type);
>     > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>     > index a858acea6547..26bc4b0d8ef0 100644
>     > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>     > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>     > @@ -188,6 +188,8 @@ const char *v4l2_type_names[] = {
>     >       [V4L2_BUF_TYPE_SDR_OUTPUT]         = "sdr-out",
>     >       [V4L2_BUF_TYPE_META_CAPTURE]       = "meta-cap",
>     >       [V4L2_BUF_TYPE_META_OUTPUT]        = "meta-out",
>     > +     [V4L2_BUF_TYPE_AUDIO_CAPTURE]      = "audio-cap",
>     > +     [V4L2_BUF_TYPE_AUDIO_OUTPUT]       = "audio-out",
>     >  };
>     >  EXPORT_SYMBOL(v4l2_type_names);
>     > 
>     > @@ -276,6 +278,7 @@ static void v4l_print_format(const void *arg, bool write_only)
>     >       const struct v4l2_sliced_vbi_format *sliced;
>     >       const struct v4l2_window *win;
>     >       const struct v4l2_meta_format *meta;
>     > +     const struct v4l2_audio_format *audio;
>     >       u32 pixelformat;
>     >       u32 planes;
>     >       unsigned i;
>     > @@ -346,6 +349,12 @@ static void v4l_print_format(const void *arg, bool write_only)
>     >               pr_cont(", dataformat=%p4cc, buffersize=%u\n",
>     >                       &pixelformat, meta->buffersize);
>     >               break;
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             audio = &p->fmt.audio;
>     > +             pr_cont(", rate=%u, format=%u, channels=%u, buffersize=%u\n",
>     > +                     audio->rate, audio->format, audio->channels, audio->buffersize);
>     > +             break;
>     >       }
>     >  }
>     > 
>     > @@ -927,6 +936,7 @@ static int check_fmt(struct file *file, enum v4l2_buf_type type)
>     >       bool is_tch = vfd->vfl_type == VFL_TYPE_TOUCH;
>     >       bool is_meta = vfd->vfl_type == VFL_TYPE_VIDEO &&
>     >                      (vfd->device_caps & meta_caps);
>     > +     bool is_audio = vfd->vfl_type == VFL_TYPE_AUDIO;
>     >       bool is_rx = vfd->vfl_dir != VFL_DIR_TX;
>     >       bool is_tx = vfd->vfl_dir != VFL_DIR_RX;
>     > 
>     > @@ -992,6 +1002,14 @@ static int check_fmt(struct file *file, enum v4l2_buf_type type)
>     >               if (is_meta && is_tx && ops->vidioc_g_fmt_meta_out)
>     >                       return 0;
>     >               break;
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +             if (is_audio && is_rx && ops->vidioc_g_fmt_audio_cap)
>     > +                     return 0;
>     > +             break;
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             if (is_audio && is_tx && ops->vidioc_g_fmt_audio_out)
>     > +                     return 0;
>     > +             break;
>     >       default:
>     >               break;
>     >       }
>     > @@ -1592,6 +1610,16 @@ static int v4l_enum_fmt(const struct v4l2_ioctl_ops *ops,
>     >                       break;
>     >               ret = ops->vidioc_enum_fmt_meta_out(file, fh, arg);
>     >               break;
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +             if (unlikely(!ops->vidioc_enum_fmt_audio_cap))
>     > +                     break;
>     > +             ret = ops->vidioc_enum_fmt_audio_cap(file, fh, arg);
>     > +             break;
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             if (unlikely(!ops->vidioc_enum_fmt_audio_out))
>     > +                     break;
>     > +             ret = ops->vidioc_enum_fmt_audio_out(file, fh, arg);
>     > +             break;
>     >       }
>     >       if (ret == 0)
>     >               v4l_fill_fmtdesc(p);
>     > @@ -1668,6 +1696,10 @@ static int v4l_g_fmt(const struct v4l2_ioctl_ops *ops,
>     >               return ops->vidioc_g_fmt_meta_cap(file, fh, arg);
>     >       case V4L2_BUF_TYPE_META_OUTPUT:
>     >               return ops->vidioc_g_fmt_meta_out(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +             return ops->vidioc_g_fmt_audio_cap(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             return ops->vidioc_g_fmt_audio_out(file, fh, arg);
>     >       }
>     >       return -EINVAL;
>     >  }
>     > @@ -1779,6 +1811,16 @@ static int v4l_s_fmt(const struct v4l2_ioctl_ops *ops,
>     >                       break;
>     >               memset_after(p, 0, fmt.meta);
>     >               return ops->vidioc_s_fmt_meta_out(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +             if (unlikely(!ops->vidioc_s_fmt_audio_cap))
>     > +                     break;
>     > +             memset_after(p, 0, fmt.audio);
>     > +             return ops->vidioc_s_fmt_audio_cap(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             if (unlikely(!ops->vidioc_s_fmt_audio_out))
>     > +                     break;
>     > +             memset_after(p, 0, fmt.audio);
>     > +             return ops->vidioc_s_fmt_audio_out(file, fh, arg);
>     >       }
>     >       return -EINVAL;
>     >  }
>     > @@ -1887,6 +1929,16 @@ static int v4l_try_fmt(const struct v4l2_ioctl_ops *ops,
>     >                       break;
>     >               memset_after(p, 0, fmt.meta);
>     >               return ops->vidioc_try_fmt_meta_out(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_CAPTURE:
>     > +             if (unlikely(!ops->vidioc_try_fmt_audio_cap))
>     > +                     break;
>     > +             memset_after(p, 0, fmt.audio);
>     > +             return ops->vidioc_try_fmt_audio_cap(file, fh, arg);
>     > +     case V4L2_BUF_TYPE_AUDIO_OUTPUT:
>     > +             if (unlikely(!ops->vidioc_try_fmt_audio_out))
>     > +                     break;
>     > +             memset_after(p, 0, fmt.audio);
>     > +             return ops->vidioc_try_fmt_audio_out(file, fh, arg);
>     >       }
>     >       return -EINVAL;
>     >  }
>     > diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
>     > index e0a13505f88d..0924e6d1dab1 100644
>     > --- a/include/media/v4l2-dev.h
>     > +++ b/include/media/v4l2-dev.h
>     > @@ -30,6 +30,7 @@
>     >   * @VFL_TYPE_SUBDEV: for V4L2 subdevices
>     >   * @VFL_TYPE_SDR:    for Software Defined Radio tuners
>     >   * @VFL_TYPE_TOUCH:  for touch sensors
>     > + * @VFL_TYPE_AUDIO:  for audio input/output devices
>     >   * @VFL_TYPE_MAX:    number of VFL types, must always be last in the enum
>     >   */
>     >  enum vfl_devnode_type {
>     > @@ -39,6 +40,7 @@ enum vfl_devnode_type {
>     >       VFL_TYPE_SUBDEV,
>     >       VFL_TYPE_SDR,
>     >       VFL_TYPE_TOUCH,
>     > +     VFL_TYPE_AUDIO,
>     >       VFL_TYPE_MAX /* Shall be the last one */
>     >  };
>     > 
>     > diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
>     > index edb733f21604..f840cf740ce1 100644
>     > --- a/include/media/v4l2-ioctl.h
>     > +++ b/include/media/v4l2-ioctl.h
>     > @@ -45,6 +45,12 @@ struct v4l2_fh;
>     >   * @vidioc_enum_fmt_meta_out: pointer to the function that implements
>     >   *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
>     >   *   for metadata output
>     > + * @vidioc_enum_fmt_audio_cap: pointer to the function that implements
>     > + *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
>     > + *   for audio capture
>     > + * @vidioc_enum_fmt_audio_out: pointer to the function that implements
>     > + *   :ref:`VIDIOC_ENUM_FMT <vidioc_enum_fmt>` ioctl logic
>     > + *   for audio output
>     >   * @vidioc_g_fmt_vid_cap: pointer to the function that implements
>     >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for video capture
>     >   *   in single plane mode
>     > @@ -79,6 +85,10 @@ struct v4l2_fh;
>     >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for metadata capture
>     >   * @vidioc_g_fmt_meta_out: pointer to the function that implements
>     >   *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for metadata output
>     > + * @vidioc_g_fmt_audio_cap: pointer to the function that implements
>     > + *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for audio capture
>     > + * @vidioc_g_fmt_audio_out: pointer to the function that implements
>     > + *   :ref:`VIDIOC_G_FMT <vidioc_g_fmt>` ioctl logic for audio output
>     >   * @vidioc_s_fmt_vid_cap: pointer to the function that implements
>     >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for video capture
>     >   *   in single plane mode
>     > @@ -113,6 +123,10 @@ struct v4l2_fh;
>     >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for metadata capture
>     >   * @vidioc_s_fmt_meta_out: pointer to the function that implements
>     >   *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for metadata output
>     > + * @vidioc_s_fmt_audio_cap: pointer to the function that implements
>     > + *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for audio capture
>     > + * @vidioc_s_fmt_audio_out: pointer to the function that implements
>     > + *   :ref:`VIDIOC_S_FMT <vidioc_g_fmt>` ioctl logic for audio output
>     >   * @vidioc_try_fmt_vid_cap: pointer to the function that implements
>     >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for video capture
>     >   *   in single plane mode
>     > @@ -149,6 +163,10 @@ struct v4l2_fh;
>     >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata capture
>     >   * @vidioc_try_fmt_meta_out: pointer to the function that implements
>     >   *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for metadata output
>     > + * @vidioc_try_fmt_audio_cap: pointer to the function that implements
>     > + *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for audio capture
>     > + * @vidioc_try_fmt_audio_out: pointer to the function that implements
>     > + *   :ref:`VIDIOC_TRY_FMT <vidioc_g_fmt>` ioctl logic for audio output
>     >   * @vidioc_reqbufs: pointer to the function that implements
>     >   *   :ref:`VIDIOC_REQBUFS <vidioc_reqbufs>` ioctl
>     >   * @vidioc_querybuf: pointer to the function that implements
>     > @@ -315,6 +333,10 @@ struct v4l2_ioctl_ops {
>     >                                       struct v4l2_fmtdesc *f);
>     >       int (*vidioc_enum_fmt_meta_out)(struct file *file, void *fh,
>     >                                       struct v4l2_fmtdesc *f);
>     > +     int (*vidioc_enum_fmt_audio_cap)(struct file *file, void *fh,
>     > +                                      struct v4l2_fmtdesc *f);
>     > +     int (*vidioc_enum_fmt_audio_out)(struct file *file, void *fh,
>     > +                                      struct v4l2_fmtdesc *f);
>     > 
>     >       /* VIDIOC_G_FMT handlers */
>     >       int (*vidioc_g_fmt_vid_cap)(struct file *file, void *fh,
>     > @@ -345,6 +367,10 @@ struct v4l2_ioctl_ops {
>     >                                    struct v4l2_format *f);
>     >       int (*vidioc_g_fmt_meta_out)(struct file *file, void *fh,
>     >                                    struct v4l2_format *f);
>     > +     int (*vidioc_g_fmt_audio_cap)(struct file *file, void *fh,
>     > +                                   struct v4l2_format *f);
>     > +     int (*vidioc_g_fmt_audio_out)(struct file *file, void *fh,
>     > +                                   struct v4l2_format *f);
>     > 
>     >       /* VIDIOC_S_FMT handlers */
>     >       int (*vidioc_s_fmt_vid_cap)(struct file *file, void *fh,
>     > @@ -375,6 +401,10 @@ struct v4l2_ioctl_ops {
>     >                                    struct v4l2_format *f);
>     >       int (*vidioc_s_fmt_meta_out)(struct file *file, void *fh,
>     >                                    struct v4l2_format *f);
>     > +     int (*vidioc_s_fmt_audio_cap)(struct file *file, void *fh,
>     > +                                   struct v4l2_format *f);
>     > +     int (*vidioc_s_fmt_audio_out)(struct file *file, void *fh,
>     > +                                   struct v4l2_format *f);
>     > 
>     >       /* VIDIOC_TRY_FMT handlers */
>     >       int (*vidioc_try_fmt_vid_cap)(struct file *file, void *fh,
>     > @@ -405,6 +435,10 @@ struct v4l2_ioctl_ops {
>     >                                      struct v4l2_format *f);
>     >       int (*vidioc_try_fmt_meta_out)(struct file *file, void *fh,
>     >                                      struct v4l2_format *f);
>     > +     int (*vidioc_try_fmt_audio_cap)(struct file *file, void *fh,
>     > +                                     struct v4l2_format *f);
>     > +     int (*vidioc_try_fmt_audio_out)(struct file *file, void *fh,
>     > +                                     struct v4l2_format *f);
>     > 
>     >       /* Buffer handlers */
>     >       int (*vidioc_reqbufs)(struct file *file, void *fh,
>     > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>     > index aee75eb9e686..a7af28f4c8c3 100644
>     > --- a/include/uapi/linux/videodev2.h
>     > +++ b/include/uapi/linux/videodev2.h
>     > @@ -153,6 +153,8 @@ enum v4l2_buf_type {
>     >       V4L2_BUF_TYPE_SDR_OUTPUT           = 12,
>     >       V4L2_BUF_TYPE_META_CAPTURE         = 13,
>     >       V4L2_BUF_TYPE_META_OUTPUT          = 14,
>     > +     V4L2_BUF_TYPE_AUDIO_CAPTURE        = 15,
>     > +     V4L2_BUF_TYPE_AUDIO_OUTPUT         = 16,
>     >       /* Deprecated, do not use */
>     >       V4L2_BUF_TYPE_PRIVATE              = 0x80,
>     >  };
>     > @@ -169,6 +171,7 @@ enum v4l2_buf_type {
>     >        || (type) == V4L2_BUF_TYPE_VBI_OUTPUT                  \
>     >        || (type) == V4L2_BUF_TYPE_SLICED_VBI_OUTPUT           \
>     >        || (type) == V4L2_BUF_TYPE_SDR_OUTPUT                  \
>     > +      || (type) == V4L2_BUF_TYPE_AUDIO_OUTPUT                \
>     >        || (type) == V4L2_BUF_TYPE_META_OUTPUT)
>     > 
>     >  #define V4L2_TYPE_IS_CAPTURE(type) (!V4L2_TYPE_IS_OUTPUT(type))
>     > @@ -2404,6 +2407,20 @@ struct v4l2_meta_format {
>     >       __u32                           buffersize;
>     >  } __attribute__ ((packed));
>     > 
>     > +/**
>     > + * struct v4l2_audio_format - audio data format definition
>     > + * @rate:            sample rate
>     > + * @format:          sample format
>     > + * @channels:                channel numbers
>     > + * @buffersize:              maximum size in bytes required for data
>     > + */
>     > +struct v4l2_audio_format {
>     > +     __u32                           rate;
>     > +     __u32                           format;
>     > +     __u32                           channels;
>     > +     __u32                           buffersize;
>     > +} __attribute__ ((packed));
>     > +
>     >  /**
>     >   * struct v4l2_format - stream data format
>     >   * @type:    enum v4l2_buf_type; type of the data stream
>     > @@ -2412,6 +2429,7 @@ struct v4l2_meta_format {
>     >   * @win:     definition of an overlaid image
>     >   * @vbi:     raw VBI capture or output parameters
>     >   * @sliced:  sliced VBI capture or output parameters
>     > + * @audio:   definition of an audio format
>     >   * @raw_data:        placeholder for future extensions and custom formats
>     >   * @fmt:     union of @pix, @pix_mp, @win, @vbi, @sliced, @sdr, @meta
>     >   *           and @raw_data
>     > @@ -2426,6 +2444,7 @@ struct v4l2_format {
>     >               struct v4l2_sliced_vbi_format   sliced;  /* V4L2_BUF_TYPE_SLICED_VBI_CAPTURE */
>     >               struct v4l2_sdr_format          sdr;     /* V4L2_BUF_TYPE_SDR_CAPTURE */
>     >               struct v4l2_meta_format         meta;    /* V4L2_BUF_TYPE_META_CAPTURE */
>     > +             struct v4l2_audio_format        audio;   /* V4L2_BUF_TYPE_AUDIO_CAPTURE */
>     >               __u8    raw_data[200];                   /* user-defined */
>     >       } fmt;
>     >  };
>     > --
>     > 2.34.1
>     >
> 
>     -- 
>     Sakari Ailus
>