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 */ 53 enum AVPixelFormat av_pix_fmt; 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 */ 59 enum AVCodecID av_codec_id; 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 AVRational sample_aspect_ratio; 73 74 /** 75 * Indexed array of V4L2Buffers 76 */ 77 V4L2Buffer *buffers; 78 79 /** 80 * Readonly after init. 81 */ 82 int num_buffers; 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 */ 103 int ff_v4l2_context_init(V4L2Context* ctx); 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 */ 111 int ff_v4l2_context_set_format(V4L2Context* ctx); 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 */ 120 int ff_v4l2_context_get_format(V4L2Context* ctx, int probe); 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 */ 129 void ff_v4l2_context_release(V4L2Context* ctx); 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 */ 150 int ff_v4l2_context_dequeue_packet(V4L2Context* ctx, AVPacket* pkt); 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 */ 161 int ff_v4l2_context_dequeue_frame(V4L2Context* ctx, AVFrame* f, int timeout); 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 */ 173 int ff_v4l2_context_enqueue_packet(V4L2Context* ctx, const AVPacket* pkt); 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 */ 184 int ff_v4l2_context_enqueue_frame(V4L2Context* ctx, const AVFrame* f); 185 186 #endif // AVCODEC_V4L2_CONTEXT_H 187