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Message-Id: <5164e140428b241144396847c4485096cf6c6ae4.1583847556.git.mchehab+huawei@kernel.org>
Date: Tue, 10 Mar 2020 14:43:00 +0100
From: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To: Linux Doc Mailing List <linux-doc@...r.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
linux-kernel@...r.kernel.org, Jonathan Corbet <corbet@....net>,
linux-media@...r.kernel.org
Subject: [PATCH v2 09/22] media: docs: split cx2341x.rst into different audiences
This file contains both driver develompent documentation
(basically, firmware documentation) and IVTV-specific
documentation about VBI and raw formats, focused on uAPI
development.
Split on two, as they're usually read by different audiences.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
---
.../{cx2341x.rst => cx2341x-devel.rst} | 175 -----------------
.../media/v4l-drivers/cx2341x-uapi.rst | 179 ++++++++++++++++++
Documentation/media/v4l-drivers/index.rst | 3 +-
3 files changed, 181 insertions(+), 176 deletions(-)
rename Documentation/media/v4l-drivers/{cx2341x.rst => cx2341x-devel.rst} (91%)
create mode 100644 Documentation/media/v4l-drivers/cx2341x-uapi.rst
diff --git a/Documentation/media/v4l-drivers/cx2341x.rst b/Documentation/media/v4l-drivers/cx2341x-devel.rst
similarity index 91%
rename from Documentation/media/v4l-drivers/cx2341x.rst
rename to Documentation/media/v4l-drivers/cx2341x-devel.rst
index 8ca37deb56b6..97699df6ea2e 100644
--- a/Documentation/media/v4l-drivers/cx2341x.rst
+++ b/Documentation/media/v4l-drivers/cx2341x-devel.rst
@@ -3683,178 +3683,3 @@ Register 0x0004 holds the DMA Transfer Status:
- bit 2: DMA read error
- bit 3: DMA write error
- bit 4: Scatter-Gather array error
-
-Non-compressed file format
---------------------------
-
-The cx23416 can produce (and the cx23415 can also read) raw YUV output. The
-format of a YUV frame is specific to this chip and is called HM12. 'HM' stands
-for 'Hauppauge Macroblock', which is a misnomer as 'Conexant Macroblock' would
-be more accurate.
-
-The format is YUV 4:2:0 which uses 1 Y byte per pixel and 1 U and V byte per
-four pixels.
-
-The data is encoded as two macroblock planes, the first containing the Y
-values, the second containing UV macroblocks.
-
-The Y plane is divided into blocks of 16x16 pixels from left to right
-and from top to bottom. Each block is transmitted in turn, line-by-line.
-
-So the first 16 bytes are the first line of the top-left block, the
-second 16 bytes are the second line of the top-left block, etc. After
-transmitting this block the first line of the block on the right to the
-first block is transmitted, etc.
-
-The UV plane is divided into blocks of 16x8 UV values going from left
-to right, top to bottom. Each block is transmitted in turn, line-by-line.
-
-So the first 16 bytes are the first line of the top-left block and
-contain 8 UV value pairs (16 bytes in total). The second 16 bytes are the
-second line of 8 UV pairs of the top-left block, etc. After transmitting
-this block the first line of the block on the right to the first block is
-transmitted, etc.
-
-The code below is given as an example on how to convert HM12 to separate
-Y, U and V planes. This code assumes frames of 720x576 (PAL) pixels.
-
-The width of a frame is always 720 pixels, regardless of the actual specified
-width.
-
-If the height is not a multiple of 32 lines, then the captured video is
-missing macroblocks at the end and is unusable. So the height must be a
-multiple of 32.
-
-Raw format c example
-~~~~~~~~~~~~~~~~~~~~
-
-.. code-block:: c
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
-
- static unsigned char frame[576*720*3/2];
- static unsigned char framey[576*720];
- static unsigned char frameu[576*720 / 4];
- static unsigned char framev[576*720 / 4];
-
- static void de_macro_y(unsigned char* dst, unsigned char *src, int dstride, int w, int h)
- {
- unsigned int y, x, i;
-
- // descramble Y plane
- // dstride = 720 = w
- // The Y plane is divided into blocks of 16x16 pixels
- // Each block in transmitted in turn, line-by-line.
- for (y = 0; y < h; y += 16) {
- for (x = 0; x < w; x += 16) {
- for (i = 0; i < 16; i++) {
- memcpy(dst + x + (y + i) * dstride, src, 16);
- src += 16;
- }
- }
- }
- }
-
- static void de_macro_uv(unsigned char *dstu, unsigned char *dstv, unsigned char *src, int dstride, int w, int h)
- {
- unsigned int y, x, i;
-
- // descramble U/V plane
- // dstride = 720 / 2 = w
- // The U/V values are interlaced (UVUV...).
- // Again, the UV plane is divided into blocks of 16x16 UV values.
- // Each block in transmitted in turn, line-by-line.
- for (y = 0; y < h; y += 16) {
- for (x = 0; x < w; x += 8) {
- for (i = 0; i < 16; i++) {
- int idx = x + (y + i) * dstride;
-
- dstu[idx+0] = src[0]; dstv[idx+0] = src[1];
- dstu[idx+1] = src[2]; dstv[idx+1] = src[3];
- dstu[idx+2] = src[4]; dstv[idx+2] = src[5];
- dstu[idx+3] = src[6]; dstv[idx+3] = src[7];
- dstu[idx+4] = src[8]; dstv[idx+4] = src[9];
- dstu[idx+5] = src[10]; dstv[idx+5] = src[11];
- dstu[idx+6] = src[12]; dstv[idx+6] = src[13];
- dstu[idx+7] = src[14]; dstv[idx+7] = src[15];
- src += 16;
- }
- }
- }
- }
-
- /*************************************************************************/
- int main(int argc, char **argv)
- {
- FILE *fin;
- int i;
-
- if (argc == 1) fin = stdin;
- else fin = fopen(argv[1], "r");
-
- if (fin == NULL) {
- fprintf(stderr, "cannot open input\n");
- exit(-1);
- }
- while (fread(frame, sizeof(frame), 1, fin) == 1) {
- de_macro_y(framey, frame, 720, 720, 576);
- de_macro_uv(frameu, framev, frame + 720 * 576, 720 / 2, 720 / 2, 576 / 2);
- fwrite(framey, sizeof(framey), 1, stdout);
- fwrite(framev, sizeof(framev), 1, stdout);
- fwrite(frameu, sizeof(frameu), 1, stdout);
- }
- fclose(fin);
- return 0;
- }
-
-
-Format of embedded V4L2_MPEG_STREAM_VBI_FMT_IVTV VBI data
----------------------------------------------------------
-
-Author: Hans Verkuil <hverkuil@...all.nl>
-
-
-This section describes the V4L2_MPEG_STREAM_VBI_FMT_IVTV format of the VBI data
-embedded in an MPEG-2 program stream. This format is in part dictated by some
-hardware limitations of the ivtv driver (the driver for the Conexant cx23415/6
-chips), in particular a maximum size for the VBI data. Anything longer is cut
-off when the MPEG stream is played back through the cx23415.
-
-The advantage of this format is it is very compact and that all VBI data for
-all lines can be stored while still fitting within the maximum allowed size.
-
-The stream ID of the VBI data is 0xBD. The maximum size of the embedded data is
-4 + 43 * 36, which is 4 bytes for a header and 2 * 18 VBI lines with a 1 byte
-header and a 42 bytes payload each. Anything beyond this limit is cut off by
-the cx23415/6 firmware. Besides the data for the VBI lines we also need 36 bits
-for a bitmask determining which lines are captured and 4 bytes for a magic cookie,
-signifying that this data package contains V4L2_MPEG_STREAM_VBI_FMT_IVTV VBI data.
-If all lines are used, then there is no longer room for the bitmask. To solve this
-two different magic numbers were introduced:
-
-'itv0': After this magic number two unsigned longs follow. Bits 0-17 of the first
-unsigned long denote which lines of the first field are captured. Bits 18-31 of
-the first unsigned long and bits 0-3 of the second unsigned long are used for the
-second field.
-
-'ITV0': This magic number assumes all VBI lines are captured, i.e. it implicitly
-implies that the bitmasks are 0xffffffff and 0xf.
-
-After these magic cookies (and the 8 byte bitmask in case of cookie 'itv0') the
-captured VBI lines start:
-
-For each line the least significant 4 bits of the first byte contain the data type.
-Possible values are shown in the table below. The payload is in the following 42
-bytes.
-
-Here is the list of possible data types:
-
-.. code-block:: c
-
- #define IVTV_SLICED_TYPE_TELETEXT 0x1 // Teletext (uses lines 6-22 for PAL)
- #define IVTV_SLICED_TYPE_CC 0x4 // Closed Captions (line 21 NTSC)
- #define IVTV_SLICED_TYPE_WSS 0x5 // Wide Screen Signal (line 23 PAL)
- #define IVTV_SLICED_TYPE_VPS 0x7 // Video Programming System (PAL) (line 16)
-
diff --git a/Documentation/media/v4l-drivers/cx2341x-uapi.rst b/Documentation/media/v4l-drivers/cx2341x-uapi.rst
new file mode 100644
index 000000000000..8a7977af79d5
--- /dev/null
+++ b/Documentation/media/v4l-drivers/cx2341x-uapi.rst
@@ -0,0 +1,179 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+The cx2341x driver
+==================
+
+Non-compressed file format
+--------------------------
+
+The cx23416 can produce (and the cx23415 can also read) raw YUV output. The
+format of a YUV frame is specific to this chip and is called HM12. 'HM' stands
+for 'Hauppauge Macroblock', which is a misnomer as 'Conexant Macroblock' would
+be more accurate.
+
+The format is YUV 4:2:0 which uses 1 Y byte per pixel and 1 U and V byte per
+four pixels.
+
+The data is encoded as two macroblock planes, the first containing the Y
+values, the second containing UV macroblocks.
+
+The Y plane is divided into blocks of 16x16 pixels from left to right
+and from top to bottom. Each block is transmitted in turn, line-by-line.
+
+So the first 16 bytes are the first line of the top-left block, the
+second 16 bytes are the second line of the top-left block, etc. After
+transmitting this block the first line of the block on the right to the
+first block is transmitted, etc.
+
+The UV plane is divided into blocks of 16x8 UV values going from left
+to right, top to bottom. Each block is transmitted in turn, line-by-line.
+
+So the first 16 bytes are the first line of the top-left block and
+contain 8 UV value pairs (16 bytes in total). The second 16 bytes are the
+second line of 8 UV pairs of the top-left block, etc. After transmitting
+this block the first line of the block on the right to the first block is
+transmitted, etc.
+
+The code below is given as an example on how to convert HM12 to separate
+Y, U and V planes. This code assumes frames of 720x576 (PAL) pixels.
+
+The width of a frame is always 720 pixels, regardless of the actual specified
+width.
+
+If the height is not a multiple of 32 lines, then the captured video is
+missing macroblocks at the end and is unusable. So the height must be a
+multiple of 32.
+
+Raw format c example
+~~~~~~~~~~~~~~~~~~~~
+
+.. code-block:: c
+
+ #include <stdio.h>
+ #include <stdlib.h>
+ #include <string.h>
+
+ static unsigned char frame[576*720*3/2];
+ static unsigned char framey[576*720];
+ static unsigned char frameu[576*720 / 4];
+ static unsigned char framev[576*720 / 4];
+
+ static void de_macro_y(unsigned char* dst, unsigned char *src, int dstride, int w, int h)
+ {
+ unsigned int y, x, i;
+
+ // descramble Y plane
+ // dstride = 720 = w
+ // The Y plane is divided into blocks of 16x16 pixels
+ // Each block in transmitted in turn, line-by-line.
+ for (y = 0; y < h; y += 16) {
+ for (x = 0; x < w; x += 16) {
+ for (i = 0; i < 16; i++) {
+ memcpy(dst + x + (y + i) * dstride, src, 16);
+ src += 16;
+ }
+ }
+ }
+ }
+
+ static void de_macro_uv(unsigned char *dstu, unsigned char *dstv, unsigned char *src, int dstride, int w, int h)
+ {
+ unsigned int y, x, i;
+
+ // descramble U/V plane
+ // dstride = 720 / 2 = w
+ // The U/V values are interlaced (UVUV...).
+ // Again, the UV plane is divided into blocks of 16x16 UV values.
+ // Each block in transmitted in turn, line-by-line.
+ for (y = 0; y < h; y += 16) {
+ for (x = 0; x < w; x += 8) {
+ for (i = 0; i < 16; i++) {
+ int idx = x + (y + i) * dstride;
+
+ dstu[idx+0] = src[0]; dstv[idx+0] = src[1];
+ dstu[idx+1] = src[2]; dstv[idx+1] = src[3];
+ dstu[idx+2] = src[4]; dstv[idx+2] = src[5];
+ dstu[idx+3] = src[6]; dstv[idx+3] = src[7];
+ dstu[idx+4] = src[8]; dstv[idx+4] = src[9];
+ dstu[idx+5] = src[10]; dstv[idx+5] = src[11];
+ dstu[idx+6] = src[12]; dstv[idx+6] = src[13];
+ dstu[idx+7] = src[14]; dstv[idx+7] = src[15];
+ src += 16;
+ }
+ }
+ }
+ }
+
+ /*************************************************************************/
+ int main(int argc, char **argv)
+ {
+ FILE *fin;
+ int i;
+
+ if (argc == 1) fin = stdin;
+ else fin = fopen(argv[1], "r");
+
+ if (fin == NULL) {
+ fprintf(stderr, "cannot open input\n");
+ exit(-1);
+ }
+ while (fread(frame, sizeof(frame), 1, fin) == 1) {
+ de_macro_y(framey, frame, 720, 720, 576);
+ de_macro_uv(frameu, framev, frame + 720 * 576, 720 / 2, 720 / 2, 576 / 2);
+ fwrite(framey, sizeof(framey), 1, stdout);
+ fwrite(framev, sizeof(framev), 1, stdout);
+ fwrite(frameu, sizeof(frameu), 1, stdout);
+ }
+ fclose(fin);
+ return 0;
+ }
+
+
+Format of embedded V4L2_MPEG_STREAM_VBI_FMT_IVTV VBI data
+---------------------------------------------------------
+
+Author: Hans Verkuil <hverkuil@...all.nl>
+
+
+This section describes the V4L2_MPEG_STREAM_VBI_FMT_IVTV format of the VBI data
+embedded in an MPEG-2 program stream. This format is in part dictated by some
+hardware limitations of the ivtv driver (the driver for the Conexant cx23415/6
+chips), in particular a maximum size for the VBI data. Anything longer is cut
+off when the MPEG stream is played back through the cx23415.
+
+The advantage of this format is it is very compact and that all VBI data for
+all lines can be stored while still fitting within the maximum allowed size.
+
+The stream ID of the VBI data is 0xBD. The maximum size of the embedded data is
+4 + 43 * 36, which is 4 bytes for a header and 2 * 18 VBI lines with a 1 byte
+header and a 42 bytes payload each. Anything beyond this limit is cut off by
+the cx23415/6 firmware. Besides the data for the VBI lines we also need 36 bits
+for a bitmask determining which lines are captured and 4 bytes for a magic cookie,
+signifying that this data package contains V4L2_MPEG_STREAM_VBI_FMT_IVTV VBI data.
+If all lines are used, then there is no longer room for the bitmask. To solve this
+two different magic numbers were introduced:
+
+'itv0': After this magic number two unsigned longs follow. Bits 0-17 of the first
+unsigned long denote which lines of the first field are captured. Bits 18-31 of
+the first unsigned long and bits 0-3 of the second unsigned long are used for the
+second field.
+
+'ITV0': This magic number assumes all VBI lines are captured, i.e. it implicitly
+implies that the bitmasks are 0xffffffff and 0xf.
+
+After these magic cookies (and the 8 byte bitmask in case of cookie 'itv0') the
+captured VBI lines start:
+
+For each line the least significant 4 bits of the first byte contain the data type.
+Possible values are shown in the table below. The payload is in the following 42
+bytes.
+
+Here is the list of possible data types:
+
+.. code-block:: c
+
+ #define IVTV_SLICED_TYPE_TELETEXT 0x1 // Teletext (uses lines 6-22 for PAL)
+ #define IVTV_SLICED_TYPE_CC 0x4 // Closed Captions (line 21 NTSC)
+ #define IVTV_SLICED_TYPE_WSS 0x5 // Wide Screen Signal (line 23 PAL)
+ #define IVTV_SLICED_TYPE_VPS 0x7 // Video Programming System (PAL) (line 16)
+
diff --git a/Documentation/media/v4l-drivers/index.rst b/Documentation/media/v4l-drivers/index.rst
index dfc878c050da..f3e34ccaf365 100644
--- a/Documentation/media/v4l-drivers/index.rst
+++ b/Documentation/media/v4l-drivers/index.rst
@@ -38,7 +38,6 @@ For more details see the file COPYING in the source distribution of Linux.
bttv
cafe_ccic
cpia2
- cx2341x
cx88
davinci-vpbe
fimc
@@ -68,7 +67,9 @@ For more details see the file COPYING in the source distribution of Linux.
bttv-devel
cpia2_devel
+ cx2341x-devel
cx88-devel
vimc-devel
+ cx2341x-uapi
meye-uapi
--
2.24.1
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