Linear Pulse-Code Modulation is used to represent audio samples in buffer, the samples for each channel are interleaved.
Signed-off-by: Shengjiu Wang shengjiu.wang@nxp.com --- .../userspace-api/media/v4l/audio-formats.rst | 15 +++++ .../media/v4l/pixfmt-aud-lpcm.rst | 61 +++++++++++++++++++ .../userspace-api/media/v4l/pixfmt.rst | 1 + drivers/media/v4l2-core/v4l2-ioctl.c | 1 + include/uapi/linux/videodev2.h | 3 + 5 files changed, 81 insertions(+) create mode 100644 Documentation/userspace-api/media/v4l/audio-formats.rst create mode 100644 Documentation/userspace-api/media/v4l/pixfmt-aud-lpcm.rst
diff --git a/Documentation/userspace-api/media/v4l/audio-formats.rst b/Documentation/userspace-api/media/v4l/audio-formats.rst new file mode 100644 index 000000000000..bc52712d20d3 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/audio-formats.rst @@ -0,0 +1,15 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _audio-formats: + +************* +Audio Formats +************* + +These formats are used for :ref:`audio` interface only. + + +.. toctree:: + :maxdepth: 1 + + pixfmt-aud-lpcm diff --git a/Documentation/userspace-api/media/v4l/pixfmt-aud-lpcm.rst b/Documentation/userspace-api/media/v4l/pixfmt-aud-lpcm.rst new file mode 100644 index 000000000000..2231bd95212f --- /dev/null +++ b/Documentation/userspace-api/media/v4l/pixfmt-aud-lpcm.rst @@ -0,0 +1,61 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _v4l2-audio-fmt-lpcm: + +**************************** +V4L2_AUDIO_FMT_LPCM ('LPCM') +**************************** + +Linear Pulse-Code Modulation (LPCM) + + +Description +=========== + +LPCM audio is coded using a combination of values such as: + +Sample rate: which is the number of times per second that samples are taken, +The typical rates are 8kHz, 11025Hz, 16kHz, 22050Hz, 32kHz, 44100Hz, 48kHz, +88200Hz, 96kHz, 176400Hz, 192kHz... + +Sample format: which determines the number of possible digital values that +can be used to represent each sample. The format can be SND_PCM_FORMAT_S8, +SND_PCM_FORMAT_S16_LE, SND_PCM_FORMAT_S24_LE, SND_PCM_FORMAT_S32_LE... + +Channels: It is the "location" or "passageway" of a specific signal or +data in a piece of audio. The channel number can be 1,2,3... + +Please refer to https://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html +for more detail + +Each sample contains several channels data, the channel data format is +defined by sample format. + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + + * - Sample 0: + - Channel 0 + - Channel 1 + - Channel 2 + - Channel 3 + - ... + * - Sample 1: + - Channel 0 + - Channel 1 + - Channel 2 + - Channel 3 + - ... + * - Sample 2: + - Channel 0 + - Channel 1 + - Channel 2 + - Channel 3 + - ... + * - Sample 3: + - Channel 0 + - Channel 1 + - Channel 2 + - Channel 3 + - ... diff --git a/Documentation/userspace-api/media/v4l/pixfmt.rst b/Documentation/userspace-api/media/v4l/pixfmt.rst index 11dab4a90630..e205db5fa8af 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 + audio-formats diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c index f4d9d6279094..55fd4da10ba6 100644 --- a/drivers/media/v4l2-core/v4l2-ioctl.c +++ b/drivers/media/v4l2-core/v4l2-ioctl.c @@ -1452,6 +1452,7 @@ 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_LPCM: descr = "Audio LPCM"; break;
default: /* Compressed formats */ diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h index 3decf7d73870..ce71e9343705 100644 --- a/include/uapi/linux/videodev2.h +++ b/include/uapi/linux/videodev2.h @@ -839,6 +839,9 @@ 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 */ +#define V4L2_AUDIO_FMT_LPCM v4l2_fourcc('L', 'P', 'C', 'M') /* audio lpcm */ + /* priv field value to indicates that subsequent fields are valid. */ #define V4L2_PIX_FMT_PRIV_MAGIC 0xfeedcafe