FFmpeg
v4l2_m2m_dec.c
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1 /*
2  * V4L2 mem2mem decoders
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 #include <linux/videodev2.h>
25 #include <sys/ioctl.h>
26 #include "libavutil/pixfmt.h"
27 #include "libavutil/pixdesc.h"
28 #include "libavutil/opt.h"
29 #include "libavcodec/avcodec.h"
30 #include "libavcodec/decode.h"
31 
32 #include "v4l2_context.h"
33 #include "v4l2_m2m.h"
34 #include "v4l2_fmt.h"
35 
36 static int v4l2_try_start(AVCodecContext *avctx)
37 {
38  V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;
39  V4L2Context *const capture = &s->capture;
40  V4L2Context *const output = &s->output;
41  struct v4l2_selection selection;
42  int ret;
43 
44  /* 1. start the output process */
45  if (!output->streamon) {
46  ret = ff_v4l2_context_set_status(output, VIDIOC_STREAMON);
47  if (ret < 0) {
48  av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON on output context\n");
49  return ret;
50  }
51  }
52 
53  if (capture->streamon)
54  return 0;
55 
56  /* 2. get the capture format */
57  capture->format.type = capture->type;
58  ret = ioctl(s->fd, VIDIOC_G_FMT, &capture->format);
59  if (ret) {
60  av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_FMT ioctl\n");
61  return ret;
62  }
63 
64  /* 2.1 update the AVCodecContext */
65  avctx->pix_fmt = ff_v4l2_format_v4l2_to_avfmt(capture->format.fmt.pix_mp.pixelformat, AV_CODEC_ID_RAWVIDEO);
66  capture->av_pix_fmt = avctx->pix_fmt;
67 
68  /* 3. set the crop parameters */
69  selection.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
70  selection.r.height = avctx->coded_height;
71  selection.r.width = avctx->coded_width;
72  ret = ioctl(s->fd, VIDIOC_S_SELECTION, &selection);
73  if (!ret) {
74  ret = ioctl(s->fd, VIDIOC_G_SELECTION, &selection);
75  if (ret) {
76  av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_SELECTION ioctl\n");
77  } else {
78  av_log(avctx, AV_LOG_DEBUG, "crop output %dx%d\n", selection.r.width, selection.r.height);
79  /* update the size of the resulting frame */
80  capture->height = selection.r.height;
81  capture->width = selection.r.width;
82  }
83  }
84 
85  /* 4. init the capture context now that we have the capture format */
86  if (!capture->buffers) {
87  ret = ff_v4l2_context_init(capture);
88  if (ret) {
89  av_log(avctx, AV_LOG_DEBUG, "can't request output buffers\n");
90  return ret;
91  }
92  }
93 
94  /* 5. start the capture process */
95  ret = ff_v4l2_context_set_status(capture, VIDIOC_STREAMON);
96  if (ret) {
97  av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON, on capture context\n");
98  return ret;
99  }
100 
101  return 0;
102 }
103 
105 {
106  struct v4l2_event_subscription sub;
107  V4L2Context *output = &s->output;
108  int ret;
109 
110  /**
111  * requirements
112  */
113  memset(&sub, 0, sizeof(sub));
114  sub.type = V4L2_EVENT_SOURCE_CHANGE;
115  ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
116  if ( ret < 0) {
117  if (output->height == 0 || output->width == 0) {
119  "the v4l2 driver does not support VIDIOC_SUBSCRIBE_EVENT\n"
120  "you must provide codec_height and codec_width on input\n");
121  return ret;
122  }
123  }
124 
125  return 0;
126 }
127 
129 {
130  V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;
131  V4L2Context *const capture = &s->capture;
132  V4L2Context *const output = &s->output;
133  AVPacket avpkt = {0};
134  int ret;
135 
136  ret = ff_decode_get_packet(avctx, &avpkt);
137  if (ret < 0 && ret != AVERROR_EOF)
138  return ret;
139 
140  if (s->draining)
141  goto dequeue;
142 
143  ret = ff_v4l2_context_enqueue_packet(output, &avpkt);
144  if (ret < 0) {
145  if (ret != AVERROR(ENOMEM))
146  return ret;
147  /* no input buffers available, continue dequeing */
148  }
149 
150  if (avpkt.size) {
151  ret = v4l2_try_start(avctx);
152  if (ret) {
153  av_packet_unref(&avpkt);
154  return 0;
155  }
156  }
157 
158 dequeue:
159  av_packet_unref(&avpkt);
160  return ff_v4l2_context_dequeue_frame(capture, frame);
161 }
162 
164 {
165  V4L2Context *capture, *output;
166  V4L2m2mContext *s;
167  int ret;
168 
169  ret = ff_v4l2_m2m_create_context(avctx, &s);
170  if (ret < 0)
171  return ret;
172 
173  capture = &s->capture;
174  output = &s->output;
175 
176  /* if these dimensions are invalid (ie, 0 or too small) an event will be raised
177  * by the v4l2 driver; this event will trigger a full pipeline reconfig and
178  * the proper values will be retrieved from the kernel driver.
179  */
180  output->height = capture->height = avctx->coded_height;
181  output->width = capture->width = avctx->coded_width;
182 
183  output->av_codec_id = avctx->codec_id;
184  output->av_pix_fmt = AV_PIX_FMT_NONE;
185 
187  capture->av_pix_fmt = avctx->pix_fmt;
188 
189  ret = ff_v4l2_m2m_codec_init(avctx);
190  if (ret) {
191  V4L2m2mPriv *priv = avctx->priv_data;
192  av_log(avctx, AV_LOG_ERROR, "can't configure decoder\n");
193  s->self_ref = NULL;
195 
196  return ret;
197  }
198 
199  return v4l2_prepare_decoder(s);
200 }
201 
202 #define OFFSET(x) offsetof(V4L2m2mPriv, x)
203 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
204 
205 static const AVOption options[] = {
207  { "num_capture_buffers", "Number of buffers in the capture context",
208  OFFSET(num_capture_buffers), AV_OPT_TYPE_INT, {.i64 = 20}, 20, INT_MAX, FLAGS },
209  { NULL},
210 };
211 
212 #define M2MDEC(NAME, LONGNAME, CODEC, bsf_name) \
213 static const AVClass v4l2_m2m_ ## NAME ## _dec_class = {\
214  .class_name = #NAME "_v4l2_m2m_decoder",\
215  .item_name = av_default_item_name,\
216  .option = options,\
217  .version = LIBAVUTIL_VERSION_INT,\
218 };\
219 \
220 AVCodec ff_ ## NAME ## _v4l2m2m_decoder = { \
221  .name = #NAME "_v4l2m2m" ,\
222  .long_name = NULL_IF_CONFIG_SMALL("V4L2 mem2mem " LONGNAME " decoder wrapper"),\
223  .type = AVMEDIA_TYPE_VIDEO,\
224  .id = CODEC ,\
225  .priv_data_size = sizeof(V4L2m2mPriv),\
226  .priv_class = &v4l2_m2m_ ## NAME ## _dec_class,\
227  .init = v4l2_decode_init,\
228  .receive_frame = v4l2_receive_frame,\
229  .close = ff_v4l2_m2m_codec_end,\
230  .bsfs = bsf_name, \
231  .capabilities = AV_CODEC_CAP_HARDWARE | AV_CODEC_CAP_DELAY | \
232  AV_CODEC_CAP_AVOID_PROBING, \
233  .wrapper_name = "v4l2m2m", \
234 };
235 
236 M2MDEC(h264, "H.264", AV_CODEC_ID_H264, "h264_mp4toannexb");
237 M2MDEC(hevc, "HEVC", AV_CODEC_ID_HEVC, "hevc_mp4toannexb");
238 M2MDEC(mpeg1, "MPEG1", AV_CODEC_ID_MPEG1VIDEO, NULL);
239 M2MDEC(mpeg2, "MPEG2", AV_CODEC_ID_MPEG2VIDEO, NULL);
240 M2MDEC(mpeg4, "MPEG4", AV_CODEC_ID_MPEG4, NULL);
241 M2MDEC(h263, "H.263", AV_CODEC_ID_H263, NULL);
242 M2MDEC(vc1 , "VC1", AV_CODEC_ID_VC1, NULL);
243 M2MDEC(vp8, "VP8", AV_CODEC_ID_VP8, NULL);
244 M2MDEC(vp9, "VP9", AV_CODEC_ID_VP9, NULL);
enum AVPixelFormat ff_v4l2_format_v4l2_to_avfmt(uint32_t v4l2_fmt, enum AVCodecID avcodec)
Definition: v4l2_fmt.c:132
#define NULL
Definition: coverity.c:32
void av_buffer_unref(AVBufferRef **buf)
Free a given reference and automatically free the buffer if there are no more references to it...
Definition: buffer.c:125
static const AVOption options[]
Definition: v4l2_m2m_dec.c:205
This structure describes decoded (raw) audio or video data.
Definition: frame.h:268
AVOption.
Definition: opt.h:246
AVCodecContext * avctx
Definition: v4l2_m2m.h:52
int coded_width
Bitstream width / height, may be different from width/height e.g.
Definition: avcodec.h:1753
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:661
int size
Definition: avcodec.h:1478
#define FLAGS
Definition: v4l2_m2m_dec.c:203
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1775
int ff_v4l2_context_dequeue_frame(V4L2Context *ctx, AVFrame *frame)
Dequeues a buffer from a V4L2Context to an AVFrame.
Definition: v4l2_context.c:574
int width
Width and height of the frames it produces (in case of a capture context, e.g.
Definition: v4l2_context.h:71
int ff_v4l2_m2m_codec_init(AVCodecContext *avctx)
Probes the video nodes looking for the required codec capabilities.
Definition: v4l2_m2m.c:341
enum AVCodecID av_codec_id
AVCodecID corresponding to this buffer context.
Definition: v4l2_context.h:59
#define av_cold
Definition: attributes.h:82
AVOptions.
#define OFFSET(x)
Definition: v4l2_m2m_dec.c:202
static int v4l2_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Definition: v4l2_m2m_dec.c:128
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce output
int ff_decode_get_packet(AVCodecContext *avctx, AVPacket *pkt)
Called by decoders to get the next packet for decoding.
Definition: decode.c:329
#define AVERROR_EOF
End of file.
Definition: error.h:55
#define av_log(a,...)
int ff_v4l2_m2m_create_context(AVCodecContext *avctx, V4L2m2mContext **s)
Allocate a new context and references for a V4L2 M2M instance.
Definition: v4l2_m2m.c:382
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
enum AVPixelFormat av_pix_fmt
AVPixelFormat corresponding to this buffer context.
Definition: v4l2_context.h:53
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_enqueue_packet(V4L2Context *ctx, const AVPacket *pkt)
Enqueues a buffer to a V4L2Context from an AVPacket.
Definition: v4l2_context.c:549
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
#define s(width, name)
Definition: cbs_vp9.c:257
preferred ID for MPEG-1/2 video decoding
Definition: avcodec.h:220
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:65
int ff_v4l2_context_set_status(V4L2Context *ctx, uint32_t cmd)
Sets the status of a V4L2Context.
Definition: v4l2_context.c:510
static int v4l2_try_start(AVCodecContext *avctx)
Definition: v4l2_m2m_dec.c:36
V4L2Context capture
Definition: v4l2_m2m.h:48
Libavcodec external API header.
enum AVCodecID codec_id
Definition: avcodec.h:1575
main external API structure.
Definition: avcodec.h:1565
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
int coded_height
Definition: avcodec.h:1753
#define M2MDEC(NAME, LONGNAME, CODEC, bsf_name)
Definition: v4l2_m2m_dec.c:212
static int v4l2_prepare_decoder(V4L2m2mContext *s)
Definition: v4l2_m2m_dec.c:104
static av_cold int v4l2_decode_init(AVCodecContext *avctx)
Definition: v4l2_m2m_dec.c:163
V4L2Context output
Definition: v4l2_m2m.h:49
AVBufferRef * self_ref
Definition: v4l2_m2m.h:61
void * priv_data
Definition: avcodec.h:1592
pixel format definitions
#define V4L_M2M_DEFAULT_OPTS
Definition: v4l2_m2m.h:39
AVBufferRef * context_ref
Definition: v4l2_m2m.h:69
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1454
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:47