On Fri, Mar 8, 2024 at 10:04 PM Hans Verkuil [off-list ref] wrote:

On 08/03/2024 2:52 pm, Shengjiu Wang wrote:

quoted

On Fri, Mar 8, 2024 at 8:06 PM Hans Verkuil [off-list ref] wrote:

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On 08/03/2024 12:52 pm, Shengjiu Wang wrote:

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On Fri, Mar 8, 2024 at 3:34 PM Hans Verkuil [off-list ref] wrote:

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Hi Shengjiu,

After thinking it over I think this patch can be improved:

On 26/02/2024 9:28 am, Shengjiu Wang wrote:

quoted

The audio sample format definition is from alsa,
the header file is include/uapi/sound/asound.h, but
don't include this header file directly, because in
user space, there is another copy in alsa-lib.
There will be conflict in userspace for include
videodev2.h & asound.h and asoundlib.h

Here still use the fourcc format.

Signed-off-by: Shengjiu Wang <redacted>
---
 .../userspace-api/media/v4l/pixfmt-audio.rst  | 87 +++++++++++++++++++
 .../userspace-api/media/v4l/pixfmt.rst        |  1 +
 drivers/media/v4l2-core/v4l2-ioctl.c          | 13 +++
 include/uapi/linux/videodev2.h                | 23 +++++
 4 files changed, 124 insertions(+)
 create mode 100644 Documentation/userspace-api/media/v4l/pixfmt-audio.rst

diff --git a/Documentation/userspace-api/media/v4l/pixfmt-audio.rst b/Documentation/userspace-api/media/v4l/pixfmt-audio.rst
new file mode 100644
index 000000000000..04b4a7fbd8f4
--- /dev/null
+++ b/Documentation/userspace-api/media/v4l/pixfmt-audio.rst

@@ -0,0 +1,87 @@
+.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
+
+.. _pixfmt-audio:
+
+*************
+Audio Formats
+*************
+
+These formats are used for :ref:`audiomem2mem` interface only.

Here you should also document that all these fourccs start with 'AU' and are
reserved for mappings of the snd_pcm_format_t type.

Also document the v4l2_fourcc_to_audfmt define and the v4l2_audfmt_to_fourcc
define (see also below).

How about below description?
'
All these fourccs starting with 'AU' are reserved for mappings

All these fourccs -> All FourCCs

quoted

of the snd_pcm_format_t type.

The v4l2_audfmt_to_fourcc() is defined to convert snd_pcm_format_t

convert -> convert the

quoted

type to fourcc. The first character is 'A', the second character

fourcc -> a FourCC

quoted

is 'U', the third character is ten's digit of snd_pcm_format_t,
the fourth character is unit's digit of snd_pcm_format_t.

"is 'U', and the remaining two characters is the snd_pcm_format_t
value in ASCII. Example: SNDRV_PCM_FORMAT_S16_LE (with value 2)
maps to 'AU02' and SNDRV_PCM_FORMAT_S24_3LE (with value 32) maps
to 'AU32'."

quoted

The v4l2_fourcc_to_audfmt() is defined to convert these fourccs to

fourccs -> FourCCs

quoted

snd_pcm_format_t type.

BTW, given the way snd_pcm_format_t is defined I am fairly certain
some casts are needed for the v4l2_audfmt_to_fourcc define.

Regards,

        Hans

quoted

'
Best regards
Shengjiu Wang

quoted

quoted

+
+.. tabularcolumns:: |p{5.8cm}|p{1.2cm}|p{10.3cm}|
+
+.. cssclass:: longtable
+
+.. flat-table:: Audio Format
+    :header-rows:  1
+    :stub-columns: 0
+    :widths:       3 1 4
+
+    * - Identifier
+      - Code
+      - Details
+    * .. _V4L2-AUDIO-FMT-S8:
+
+      - ``V4L2_AUDIO_FMT_S8``
+      - 'S8'
+      - Corresponds to SNDRV_PCM_FORMAT_S8 in ALSA
+    * .. _V4L2-AUDIO-FMT-S16-LE:
+
+      - ``V4L2_AUDIO_FMT_S16_LE``
+      - 'S16_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_S16_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-U16-LE:
+
+      - ``V4L2_AUDIO_FMT_U16_LE``
+      - 'U16_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_U16_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-S24-LE:
+
+      - ``V4L2_AUDIO_FMT_S24_LE``
+      - 'S24_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_S24_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-U24-LE:
+
+      - ``V4L2_AUDIO_FMT_U24_LE``
+      - 'U24_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_U24_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-S32-LE:
+
+      - ``V4L2_AUDIO_FMT_S32_LE``
+      - 'S32_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_S32_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-U32-LE:
+
+      - ``V4L2_AUDIO_FMT_U32_LE``
+      - 'U32_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_U32_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-FLOAT-LE:
+
+      - ``V4L2_AUDIO_FMT_FLOAT_LE``
+      - 'FLOAT_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_FLOAT_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-IEC958-SUBFRAME-LE:
+
+      - ``V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE``
+      - 'IEC958_SUBFRAME_LE'
+      - Corresponds to SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE in ALSA
+    * .. _V4L2-AUDIO-FMT-S24-3LE:
+
+      - ``V4L2_AUDIO_FMT_S24_3LE``
+      - 'S24_3LE'
+      - Corresponds to SNDRV_PCM_FORMAT_S24_3LE in ALSA
+    * .. _V4L2-AUDIO-FMT-U24-3LE:
+
+      - ``V4L2_AUDIO_FMT_U24_3LE``
+      - 'U24_3LE'
+      - Corresponds to SNDRV_PCM_FORMAT_U24_3LE in ALSA
+    * .. _V4L2-AUDIO-FMT-S20-3LE:
+
+      - ``V4L2_AUDIO_FMT_S20_3LE``
+      - 'S20_3LE'
+      - Corresponds to SNDRV_PCM_FORMAT_S24_3LE in ALSA
+    * .. _V4L2-AUDIO-FMT-U20-3LE:
+
+      - ``V4L2_AUDIO_FMT_U20_3LE``
+      - 'U20_3LE'
+      - Corresponds to SNDRV_PCM_FORMAT_U20_3LE in ALSA

diff --git a/Documentation/userspace-api/media/v4l/pixfmt.rst b/Documentation/userspace-api/media/v4l/pixfmt.rst
index 11dab4a90630..2eb6fdd3b43d 100644
--- a/Documentation/userspace-api/media/v4l/pixfmt.rst
+++ b/Documentation/userspace-api/media/v4l/pixfmt.rst

@@ -36,3 +36,4 @@ see also :ref:`VIDIOC_G_FBUF <VIDIOC_G_FBUF>`.)
     colorspaces
     colorspaces-defs
     colorspaces-details
+    pixfmt-audio

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 961abcdf7290..be229c69e991 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c

@@ -1471,6 +1471,19 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
      case V4L2_PIX_FMT_Y210:         descr = "10-bit YUYV Packed"; break;
      case V4L2_PIX_FMT_Y212:         descr = "12-bit YUYV Packed"; break;
      case V4L2_PIX_FMT_Y216:         descr = "16-bit YUYV Packed"; break;
+     case V4L2_AUDIO_FMT_S8:         descr = "8-bit Signed"; break;
+     case V4L2_AUDIO_FMT_S16_LE:     descr = "16-bit Signed LE"; break;
+     case V4L2_AUDIO_FMT_U16_LE:             descr = "16-bit Unsigned LE"; break;
+     case V4L2_AUDIO_FMT_S24_LE:             descr = "24(32)-bit Signed LE"; break;
+     case V4L2_AUDIO_FMT_U24_LE:             descr = "24(32)-bit Unsigned LE"; break;
+     case V4L2_AUDIO_FMT_S32_LE:             descr = "32-bit Signed LE"; break;
+     case V4L2_AUDIO_FMT_U32_LE:             descr = "32-bit Unsigned LE"; break;
+     case V4L2_AUDIO_FMT_FLOAT_LE:           descr = "32-bit Float LE"; break;
+     case V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE: descr = "32-bit IEC958 LE"; break;
+     case V4L2_AUDIO_FMT_S24_3LE:            descr = "24(24)-bit Signed LE"; break;
+     case V4L2_AUDIO_FMT_U24_3LE:            descr = "24(24)-bit Unsigned LE"; break;
+     case V4L2_AUDIO_FMT_S20_3LE:            descr = "20(24)-bit Signed LE"; break;
+     case V4L2_AUDIO_FMT_U20_3LE:            descr = "20(24)-bit Unsigned LE"; break;

      default:
              /* Compressed formats */

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 2c03d2dfadbe..673a6235a029 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h

@@ -843,6 +843,29 @@ struct v4l2_pix_format {
 #define V4L2_META_FMT_RK_ISP1_PARAMS v4l2_fourcc('R', 'K', '1', 'P') /* Rockchip ISP1 3A Parameters */
 #define V4L2_META_FMT_RK_ISP1_STAT_3A        v4l2_fourcc('R', 'K', '1', 'S') /* Rockchip ISP1 3A Statistics */

+/*
+ * Audio-data formats
+ * All these audio formats use a fourcc starting with 'AU'
+ * followed by the SNDRV_PCM_FORMAT_ value from asound.h.

Also document here that fourccs starting with 'AU' are reserved for
the snd_pcm_format_t to fourcc mappings.

That to avoid that someone adds a 'AUXX' fourcc later.

quoted

+ */
+#define V4L2_AUDIO_FMT_S8                    v4l2_fourcc('A', 'U', '0', '0')
+#define V4L2_AUDIO_FMT_S16_LE                        v4l2_fourcc('A', 'U', '0', '2')
+#define V4L2_AUDIO_FMT_U16_LE                        v4l2_fourcc('A', 'U', '0', '4')
+#define V4L2_AUDIO_FMT_S24_LE                        v4l2_fourcc('A', 'U', '0', '6')
+#define V4L2_AUDIO_FMT_U24_LE                        v4l2_fourcc('A', 'U', '0', '8')
+#define V4L2_AUDIO_FMT_S32_LE                        v4l2_fourcc('A', 'U', '1', '0')
+#define V4L2_AUDIO_FMT_U32_LE                        v4l2_fourcc('A', 'U', '1', '2')
+#define V4L2_AUDIO_FMT_FLOAT_LE                      v4l2_fourcc('A', 'U', '1', '4')
+#define V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE    v4l2_fourcc('A', 'U', '1', '8')
+#define V4L2_AUDIO_FMT_S24_3LE                       v4l2_fourcc('A', 'U', '3', '2')
+#define V4L2_AUDIO_FMT_U24_3LE                       v4l2_fourcc('A', 'U', '3', '4')
+#define V4L2_AUDIO_FMT_S20_3LE                       v4l2_fourcc('A', 'U', '3', '6')
+#define V4L2_AUDIO_FMT_U20_3LE                       v4l2_fourcc('A', 'U', '3', '8')
+
+#define v4l2_fourcc_to_audfmt(fourcc)        \
+     (__force snd_pcm_format_t)(((((fourcc) >> 16) & 0xff) - '0') * 10  \
+                                + ((((fourcc) >> 24) & 0xff) - '0'))
+

As I suggested in an earlier reply, add this:

#define v4l2_audfmt_to_fourcc(audfmt) \
        v4l2_fourcc('A', 'U', '0' + (audfmt) / 10, '0' + (audfmt) % 10)

Even though it is not used in the drivers, since this is a public header used
by drivers and applications, it makes sense to provide the reverse mapping as well.

Please test it in actual code to make sure there are no compilation warnings.

I test this definition, the compiler doesn't report warning.

typedef int __bitwise snd_pcm_format_t;

And __bitwise is apparently a sparse static analyzer attribute, so I suspect that the
v4l2_audfmt_to_fourcc definition will cause a sparse warning. So you need to check
with sparse.

Thanks,  with sparse there is warning, I will fix it.

best regards
Shengjiu Wang

Regards,

        Hans

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best regards
Shengjiu Wang

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quoted

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Regards,

        Hans

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 /* priv field value to indicates that subsequent fields are valid. */
 #define V4L2_PIX_FMT_PRIV_MAGIC              0xfeedcafe