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;
73 
74  /**
75  * Indexed array of V4L2Buffers
76  */
78 
79  /**
80  * Readonly after init.
81  */
83 
84  /**
85  * Whether the stream has been started (VIDIOC_STREAMON has been sent).
86  */
87  int streamon;
88 
89  /**
90  * Either no more buffers available or an unrecoverable error was notified
91  * by the V4L2 kernel driver: once set the context has to be exited.
92  */
93  int done;
94 
95 } V4L2Context;
96 
97 /**
98  * Initializes a V4L2Context.
99  *
100  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
101  * @return 0 in case of success, a negative value representing the error otherwise.
102  */
104 
105 /**
106  * Sets the V4L2Context format in the v4l2 driver.
107  *
108  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
109  * @return 0 in case of success, a negative value representing the error otherwise.
110  */
112 
113 /**
114  * Queries the driver for a valid v4l2 format and copies it to the context.
115  *
116  * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
117  * @param[in] probe Probe only and ignore changes to the format.
118  * @return 0 in case of success, a negative value representing the error otherwise.
119  */
121 
122 /**
123  * Releases a V4L2Context.
124  *
125  * @param[in] ctx A pointer to a V4L2Context.
126  * The caller is reponsible for freeing it.
127  * It must not be used after calling this function.
128  */
130 
131 /**
132  * Sets the status of a V4L2Context.
133  *
134  * @param[in] ctx A pointer to a V4L2Context.
135  * @param[in] cmd The status to set (VIDIOC_STREAMON or VIDIOC_STREAMOFF).
136  * Warning: If VIDIOC_STREAMOFF is sent to a buffer context that still has some frames buffered,
137  * those frames will be dropped.
138  * @return 0 in case of success, a negative value representing the error otherwise.
139  */
140 int ff_v4l2_context_set_status(V4L2Context* ctx, uint32_t cmd);
141 
142 /**
143  * Dequeues a buffer from a V4L2Context to an AVPacket.
144  *
145  * The pkt must be non NULL.
146  * @param[in] ctx The V4L2Context to dequeue from.
147  * @param[inout] pkt The AVPacket to dequeue to.
148  * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
149  */
151 
152 /**
153  * Dequeues a buffer from a V4L2Context to an AVFrame.
154  *
155  * The frame must be non NULL.
156  * @param[in] ctx The V4L2Context to dequeue from.
157  * @param[inout] f The AVFrame to dequeue to.
158  * @param[in] timeout The timeout for dequeue (-1 to block, 0 to return immediately, or milliseconds)
159  * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
160  */
162 
163 /**
164  * Enqueues a buffer to a V4L2Context from an AVPacket
165  *
166  * The packet must be non NULL.
167  * 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.
168  *
169  * @param[in] ctx The V4L2Context to enqueue to.
170  * @param[in] pkt A pointer to an AVPacket.
171  * @return 0 in case of success, a negative error otherwise.
172  */
174 
175 /**
176  * Enqueues a buffer to a V4L2Context from an AVFrame
177  *
178  * The frame must be non NULL.
179  *
180  * @param[in] ctx The V4L2Context to enqueue to.
181  * @param[in] f A pointer to an AVFrame to enqueue.
182  * @return 0 in case of success, a negative error otherwise.
183  */
185 
186 #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:677
int ff_v4l2_context_dequeue_packet(V4L2Context *ctx, AVPacket *pkt)
Dequeues a buffer from a V4L2Context to an AVPacket.
Definition: v4l2_context.c:625
int ff_v4l2_context_get_format(V4L2Context *ctx, int probe)
Queries the driver for a valid v4l2 format and copies it to the context.
Definition: v4l2_context.c:645
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
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:555
int done
Either no more buffers available or an unrecoverable error was notified by the V4L2 kernel driver: on...
Definition: v4l2_context.h:93
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:77
int streamon
Whether the stream has been started (VIDIOC_STREAMON has been sent).
Definition: v4l2_context.h:87
int ff_v4l2_context_set_format(V4L2Context *ctx)
Sets the V4L2Context format in the v4l2 driver.
Definition: v4l2_context.c:672
AVFormatContext * ctx
Definition: movenc.c:48
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:692
int ff_v4l2_context_enqueue_packet(V4L2Context *ctx, const AVPacket *pkt)
Enqueues a buffer to a V4L2Context from an AVPacket.
Definition: v4l2_context.c:580
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:65
AVRational sample_aspect_ratio
Definition: v4l2_context.h:72
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:541
V4L2Buffer (wrapper for v4l2_buffer management)
Definition: v4l2_buffers.h:41
Rational number (pair of numerator and denominator).
Definition: rational.h:58
refcounted data buffer API
static int probe(const AVProbeData *p)
Definition: act.c:36
pixel format definitions
int num_buffers
Readonly after init.
Definition: v4l2_context.h:82
int ff_v4l2_context_dequeue_frame(V4L2Context *ctx, AVFrame *f, int timeout)
Dequeues a buffer from a V4L2Context to an AVFrame.
Definition: v4l2_context.c:605
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
This structure stores compressed data.
Definition: avcodec.h:1457
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:47