1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
2
3.. _packed-yuv:
4
5******************
6Packed YUV formats
7******************
8
9Similarly to the packed RGB formats, the packed YUV formats store the Y, Cb and
10Cr components consecutively in memory. They may apply subsampling to the chroma
11components and thus differ in how they interlave the three components.
12
13.. note::
14
15   - In all the tables that follow, bit 7 is the most significant bit in a byte.
16   - 'Y', 'Cb' and 'Cr' denote bits of the luma, blue chroma (also known as
17     'U') and red chroma (also known as 'V') components respectively. 'A'
18     denotes bits of the alpha component (if supported by the format), and 'X'
19     denotes padding bits.
20
21
224:4:4 Subsampling
23=================
24
25These formats do not subsample the chroma components and store each pixels as a
26full triplet of Y, Cb and Cr values.
27
28The next table lists the packed YUV 4:4:4 formats with less than 8 bits per
29component. They are named based on the order of the Y, Cb and Cr components as
30seen in a 16-bit word, which is then stored in memory in little endian byte
31order, and on the number of bits for each component. For instance the YUV565
32format stores a pixel in a 16-bit word [15:0] laid out at as [Y'\ :sub:`4-0`
33Cb\ :sub:`5-0` Cr\ :sub:`4-0`], and stored in memory in two bytes,
34[Cb\ :sub:`2-0` Cr\ :sub:`4-0`] followed by [Y'\ :sub:`4-0` Cb\ :sub:`5-3`].
35
36.. raw:: latex
37
38    \begingroup
39    \tiny
40    \setlength{\tabcolsep}{2pt}
41
42.. tabularcolumns:: |p{2.5cm}|p{0.69cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|p{0.31cm}|
43
44.. flat-table:: Packed YUV 4:4:4 Image Formats (less than 8bpc)
45    :header-rows:  2
46    :stub-columns: 0
47
48    * - Identifier
49      - Code
50
51      - :cspan:`7` Byte 0 in memory
52
53      - :cspan:`7` Byte 1
54
55    * -
56      -
57      - 7
58      - 6
59      - 5
60      - 4
61      - 3
62      - 2
63      - 1
64      - 0
65
66      - 7
67      - 6
68      - 5
69      - 4
70      - 3
71      - 2
72      - 1
73      - 0
74
75    * .. _V4L2-PIX-FMT-YUV444:
76
77      - ``V4L2_PIX_FMT_YUV444``
78      - 'Y444'
79
80      - Cb\ :sub:`3`
81      - Cb\ :sub:`2`
82      - Cb\ :sub:`1`
83      - Cb\ :sub:`0`
84      - Cr\ :sub:`3`
85      - Cr\ :sub:`2`
86      - Cr\ :sub:`1`
87      - Cr\ :sub:`0`
88
89      - a\ :sub:`3`
90      - a\ :sub:`2`
91      - a\ :sub:`1`
92      - a\ :sub:`0`
93      - Y'\ :sub:`3`
94      - Y'\ :sub:`2`
95      - Y'\ :sub:`1`
96      - Y'\ :sub:`0`
97
98    * .. _V4L2-PIX-FMT-YUV555:
99
100      - ``V4L2_PIX_FMT_YUV555``
101      - 'YUVO'
102
103      - Cb\ :sub:`2`
104      - Cb\ :sub:`1`
105      - Cb\ :sub:`0`
106      - Cr\ :sub:`4`
107      - Cr\ :sub:`3`
108      - Cr\ :sub:`2`
109      - Cr\ :sub:`1`
110      - Cr\ :sub:`0`
111
112      - a
113      - Y'\ :sub:`4`
114      - Y'\ :sub:`3`
115      - Y'\ :sub:`2`
116      - Y'\ :sub:`1`
117      - Y'\ :sub:`0`
118      - Cb\ :sub:`4`
119      - Cb\ :sub:`3`
120
121    * .. _V4L2-PIX-FMT-YUV565:
122
123      - ``V4L2_PIX_FMT_YUV565``
124      - 'YUVP'
125
126      - Cb\ :sub:`2`
127      - Cb\ :sub:`1`
128      - Cb\ :sub:`0`
129      - Cr\ :sub:`4`
130      - Cr\ :sub:`3`
131      - Cr\ :sub:`2`
132      - Cr\ :sub:`1`
133      - Cr\ :sub:`0`
134
135      - Y'\ :sub:`4`
136      - Y'\ :sub:`3`
137      - Y'\ :sub:`2`
138      - Y'\ :sub:`1`
139      - Y'\ :sub:`0`
140      - Cb\ :sub:`5`
141      - Cb\ :sub:`4`
142      - Cb\ :sub:`3`
143
144.. raw:: latex
145
146    \endgroup
147
148.. note::
149
150    For the YUV444 and YUV555 formats, the value of alpha bits is undefined
151    when reading from the driver, ignored when writing to the driver, except
152    when alpha blending has been negotiated for a :ref:`Video Overlay
153    <overlay>` or :ref:`Video Output Overlay <osd>`.
154
155
156The next table lists the packed YUV 4:4:4 formats with 8 bits per component.
157They are named based on the order of the Y, Cb and Cr components as stored in
158memory, and on the total number of bits per pixel. For instance, the VUYX32
159format stores a pixel with Cr\ :sub:`7-0` in the first byte, Cb\ :sub:`7-0` in
160the second byte and Y'\ :sub:`7-0` in the third byte.
161
162.. flat-table:: Packed YUV Image Formats (8bpc)
163    :header-rows: 1
164    :stub-columns: 0
165
166    * - Identifier
167      - Code
168      - Byte 0
169      - Byte 1
170      - Byte 2
171      - Byte 3
172
173    * .. _V4L2-PIX-FMT-YUV32:
174
175      - ``V4L2_PIX_FMT_YUV32``
176      - 'YUV4'
177
178      - A\ :sub:`7-0`
179      - Y'\ :sub:`7-0`
180      - Cb\ :sub:`7-0`
181      - Cr\ :sub:`7-0`
182
183    * .. _V4L2-PIX-FMT-AYUV32:
184
185      - ``V4L2_PIX_FMT_AYUV32``
186      - 'AYUV'
187
188      - A\ :sub:`7-0`
189      - Y'\ :sub:`7-0`
190      - Cb\ :sub:`7-0`
191      - Cr\ :sub:`7-0`
192
193    * .. _V4L2-PIX-FMT-XYUV32:
194
195      - ``V4L2_PIX_FMT_XYUV32``
196      - 'XYUV'
197
198      - X\ :sub:`7-0`
199      - Y'\ :sub:`7-0`
200      - Cb\ :sub:`7-0`
201      - Cr\ :sub:`7-0`
202
203    * .. _V4L2-PIX-FMT-VUYA32:
204
205      - ``V4L2_PIX_FMT_VUYA32``
206      - 'VUYA'
207
208      - Cr\ :sub:`7-0`
209      - Cb\ :sub:`7-0`
210      - Y'\ :sub:`7-0`
211      - A\ :sub:`7-0`
212
213    * .. _V4L2-PIX-FMT-VUYX32:
214
215      - ``V4L2_PIX_FMT_VUYX32``
216      - 'VUYX'
217
218      - Cr\ :sub:`7-0`
219      - Cb\ :sub:`7-0`
220      - Y'\ :sub:`7-0`
221      - X\ :sub:`7-0`
222
223.. note::
224
225    - The alpha component is expected to contain a meaningful value that can be
226      used by drivers and applications.
227    - The padding bits contain undefined values that must be ignored by all
228      applications and drivers.
229
230
2314:2:2 Subsampling
232=================
233
234These formats, commonly referred to as YUYV or YUY2, subsample the chroma
235components horizontally by 2, storing 2 pixels in 4 bytes.
236
237.. flat-table:: Packed YUV 4:2:2 Formats
238    :header-rows: 1
239    :stub-columns: 0
240
241    * - Identifier
242      - Code
243      - Byte 0
244      - Byte 1
245      - Byte 2
246      - Byte 3
247      - Byte 4
248      - Byte 5
249      - Byte 6
250      - Byte 7
251    * .. _V4L2-PIX-FMT-UYVY:
252
253      - ``V4L2_PIX_FMT_UYVY``
254      - 'UYVY'
255
256      - Cb\ :sub:`0`
257      - Y'\ :sub:`0`
258      - Cr\ :sub:`0`
259      - Y'\ :sub:`1`
260      - Cb\ :sub:`2`
261      - Y'\ :sub:`2`
262      - Cr\ :sub:`2`
263      - Y'\ :sub:`3`
264    * .. _V4L2-PIX-FMT-VYUY:
265
266      - ``V4L2_PIX_FMT_VYUY``
267      - 'VYUY'
268
269      - Cr\ :sub:`0`
270      - Y'\ :sub:`0`
271      - Cb\ :sub:`0`
272      - Y'\ :sub:`1`
273      - Cr\ :sub:`2`
274      - Y'\ :sub:`2`
275      - Cb\ :sub:`2`
276      - Y'\ :sub:`3`
277    * .. _V4L2-PIX-FMT-YUYV:
278
279      - ``V4L2_PIX_FMT_YUYV``
280      - 'YUYV'
281
282      - Y'\ :sub:`0`
283      - Cb\ :sub:`0`
284      - Y'\ :sub:`1`
285      - Cr\ :sub:`0`
286      - Y'\ :sub:`2`
287      - Cb\ :sub:`2`
288      - Y'\ :sub:`3`
289      - Cr\ :sub:`2`
290    * .. _V4L2-PIX-FMT-YVYU:
291
292      - ``V4L2_PIX_FMT_YVYU``
293      - 'YVYU'
294
295      - Y'\ :sub:`0`
296      - Cr\ :sub:`0`
297      - Y'\ :sub:`1`
298      - Cb\ :sub:`0`
299      - Y'\ :sub:`2`
300      - Cr\ :sub:`2`
301      - Y'\ :sub:`3`
302      - Cb\ :sub:`2`
303
304**Color Sample Location:**
305Chroma samples are :ref:`interstitially sited<yuv-chroma-centered>`
306horizontally.
307
308
3094:1:1 Subsampling
310=================
311
312This format subsamples the chroma components horizontally by 4, storing 8
313pixels in 12 bytes.
314
315.. flat-table:: Packed YUV 4:1:1 Formats
316    :header-rows: 1
317    :stub-columns: 0
318
319    * - Identifier
320      - Code
321      - Byte 0
322      - Byte 1
323      - Byte 2
324      - Byte 3
325      - Byte 4
326      - Byte 5
327      - Byte 6
328      - Byte 7
329      - Byte 8
330      - Byte 9
331      - Byte 10
332      - Byte 11
333    * .. _V4L2-PIX-FMT-Y41P:
334
335      - ``V4L2_PIX_FMT_Y41P``
336      - 'Y41P'
337
338      - Cb\ :sub:`0`
339      - Y'\ :sub:`0`
340      - Cr\ :sub:`0`
341      - Y'\ :sub:`1`
342      - Cb\ :sub:`4`
343      - Y'\ :sub:`2`
344      - Cr\ :sub:`4`
345      - Y'\ :sub:`3`
346      - Y'\ :sub:`4`
347      - Y'\ :sub:`5`
348      - Y'\ :sub:`6`
349      - Y'\ :sub:`7`
350
351.. note::
352
353    Do not confuse ``V4L2_PIX_FMT_Y41P`` with
354    :ref:`V4L2_PIX_FMT_YUV411P <V4L2-PIX-FMT-YUV411P>`. Y41P is derived from
355    "YUV 4:1:1 *packed*", while YUV411P stands for "YUV 4:1:1 *planar*".
356
357**Color Sample Location:**
358Chroma samples are :ref:`interstitially sited<yuv-chroma-centered>`
359horizontally.
360