FFmpeg
v4l2_context.h
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1 /*
2  * V4L2 context helper functions.
3  *
4  * Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
5  * Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #ifndef AVCODEC_V4L2_CONTEXT_H
25 #define AVCODEC_V4L2_CONTEXT_H
26 
27 #include <stdatomic.h>
28 #include <linux/videodev2.h>
29 
30 #include "libavcodec/avcodec.h"
31 #include "libavutil/pixfmt.h"
32 #include "libavutil/frame.h"
33 #include "libavutil/buffer.h"
34 #include "v4l2_buffers.h"
35 
36 typedef struct V4L2Context {
37  /**
38  * context name.
39  */
40  const char* name;
41 
42  /**
43  * Type of this buffer context.
44  * See V4L2_BUF_TYPE_VIDEO_* in videodev2.h
45  * Readonly after init.
46  */
47  enum v4l2_buf_type type;
48 
49  /**
50  * AVPixelFormat corresponding to this buffer context.
51  * AV_PIX_FMT_NONE means this is an encoded stream.
52  */
54 
55  /**
56  * AVCodecID corresponding to this buffer context.
57  * AV_CODEC_ID_RAWVIDEO means this is a raw stream and av_pix_fmt must be set to a valid value.
58  */
60 
61  /**
62  * Format returned by the driver after initializing the buffer context.
63  * Readonly after init.
64  */
65  struct v4l2_format format;
66 
67  /**
68  * Width and height of the frames it produces (in case of a capture context, e.g. when decoding)
69  * or accepts (in case of an output context, e.g. when encoding).
70  */
71  int width, height;
72 
73  /**
74  * Indexed array of V4L2Buffers
75  */
77 
78  /**
79  * Readonly after init.
80  */
82 
83  /**
84  * Whether the stream has been started (VIDIOC_STREAMON has been sent).
85  */
86  int streamon;
87 
88  /**
89  * Either no more buffers available or an unrecoverable error was notified
90  * by the V4L2 kernel driver: once set the context has to be exited.
91  */
92  int done;
93 
94 } V4L2Context;
95 
96 /**
97  * Initializes a V4L2Context.
98  *
99  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
100  * @return 0 in case of success, a negative value representing the error otherwise.
101  */
103 
104 /**
105  * Sets the V4L2Context format in the v4l2 driver.
106  *
107  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
108  * @return 0 in case of success, a negative value representing the error otherwise.
109  */
111 
112 /**
113  * Queries the driver for a valid v4l2 format and copies it to the context.
114  *
115  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
116  * @return 0 in case of success, a negative value representing the error otherwise.
117  */
119 
120 /**
121  * Releases a V4L2Context.
122  *
123  * @param[in] ctx A pointer to a V4L2Context.
124  * The caller is reponsible for freeing it.
125  * It must not be used after calling this function.
126  */
128 
129 /**
130  * Sets the status of a V4L2Context.
131  *
132  * @param[in] ctx A pointer to a V4L2Context.
133  * @param[in] cmd The status to set (VIDIOC_STREAMON or VIDIOC_STREAMOFF).
134  * Warning: If VIDIOC_STREAMOFF is sent to a buffer context that still has some frames buffered,
135  * those frames will be dropped.
136  * @return 0 in case of success, a negative value representing the error otherwise.
137  */
138 int ff_v4l2_context_set_status(V4L2Context* ctx, uint32_t cmd);
139 
140 /**
141  * Dequeues a buffer from a V4L2Context to an AVPacket.
142  *
143  * The pkt must be non NULL.
144  * @param[in] ctx The V4L2Context to dequeue from.
145  * @param[inout] pkt The AVPacket to dequeue to.
146  * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
147  */
149 
150 /**
151  * Dequeues a buffer from a V4L2Context to an AVFrame.
152  *
153  * The frame must be non NULL.
154  * @param[in] ctx The V4L2Context to dequeue from.
155  * @param[inout] f The AVFrame to dequeue to.
156  * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
157  */
159 
160 /**
161  * Enqueues a buffer to a V4L2Context from an AVPacket
162  *
163  * The packet must be non NULL.
164  * When the size of the pkt is null, the buffer is not queued but a V4L2_DEC_CMD_STOP command is sent instead to the driver.
165  *
166  * @param[in] ctx The V4L2Context to enqueue to.
167  * @param[in] pkt A pointer to an AVPacket.
168  * @return 0 in case of success, a negative error otherwise.
169  */
171 
172 /**
173  * Enqueues a buffer to a V4L2Context from an AVFrame
174  *
175  * The frame must be non NULL.
176  *
177  * @param[in] ctx The V4L2Context to enqueue to.
178  * @param[in] f A pointer to an AVFrame to enqueue.
179  * @return 0 in case of success, a negative error otherwise.
180  */
182 
183 #endif // AVCODEC_V4L2_CONTEXT_H
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
const char * name
context name.
Definition: v4l2_context.h:40
void ff_v4l2_context_release(V4L2Context *ctx)
Releases a V4L2Context.
Definition: v4l2_context.c:646
int ff_v4l2_context_dequeue_packet(V4L2Context *ctx, AVPacket *pkt)
Dequeues a buffer from a V4L2Context to an AVPacket.
Definition: v4l2_context.c:594
int width
Width and height of the frames it produces (in case of a capture context, e.g.
Definition: v4l2_context.h:71
static AVPacket pkt
int ff_v4l2_context_dequeue_frame(V4L2Context *ctx, AVFrame *f)
Dequeues a buffer from a V4L2Context to an AVFrame.
Definition: v4l2_context.c:574
enum AVCodecID av_codec_id
AVCodecID corresponding to this buffer context.
Definition: v4l2_context.h:59
#define f(width, name)
Definition: cbs_vp9.c:255
int ff_v4l2_context_enqueue_frame(V4L2Context *ctx, const AVFrame *f)
Enqueues a buffer to a V4L2Context from an AVFrame.
Definition: v4l2_context.c:524
int done
Either no more buffers available or an unrecoverable error was notified by the V4L2 kernel driver: on...
Definition: v4l2_context.h:92
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:215
enum AVPixelFormat av_pix_fmt
AVPixelFormat corresponding to this buffer context.
Definition: v4l2_context.h:53
reference-counted frame API
V4L2Buffer * buffers
Indexed array of V4L2Buffers.
Definition: v4l2_context.h:76
int streamon
Whether the stream has been started (VIDIOC_STREAMON has been sent).
Definition: v4l2_context.h:86
int ff_v4l2_context_set_format(V4L2Context *ctx)
Sets the V4L2Context format in the v4l2 driver.
Definition: v4l2_context.c:641
AVFormatContext * ctx
Definition: movenc.c:48
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:661
int ff_v4l2_context_enqueue_packet(V4L2Context *ctx, const AVPacket *pkt)
Enqueues a buffer to a V4L2Context from an AVPacket.
Definition: v4l2_context.c:549
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:65
Libavcodec external API header.
int ff_v4l2_context_set_status(V4L2Context *ctx, uint32_t cmd)
Sets the status of a V4L2Context.
Definition: v4l2_context.c:510
V4L2Buffer (wrapper for v4l2_buffer management)
Definition: v4l2_buffers.h:41
refcounted data buffer API
int ff_v4l2_context_get_format(V4L2Context *ctx)
Queries the driver for a valid v4l2 format and copies it to the context.
Definition: v4l2_context.c:614
pixel format definitions
int num_buffers
Readonly after init.
Definition: v4l2_context.h:81
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
This structure stores compressed data.
Definition: avcodec.h:1454
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:47