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 "codec_internal.h"
31 #include "libavcodec/decode.h"
32 
33 #include "v4l2_context.h"
34 #include "v4l2_m2m.h"
35 #include "v4l2_fmt.h"
36 
37 static int v4l2_try_start(AVCodecContext *avctx)
38 {
39  V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;
40  V4L2Context *const capture = &s->capture;
41  V4L2Context *const output = &s->output;
42  struct v4l2_selection selection = { 0 };
43  int ret;
44 
45  /* 1. start the output process */
46  if (!output->streamon) {
47  ret = ff_v4l2_context_set_status(output, VIDIOC_STREAMON);
48  if (ret < 0) {
49  av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON on output context\n");
50  return ret;
51  }
52  }
53 
54  if (capture->streamon)
55  return 0;
56 
57  /* 2. get the capture format */
58  capture->format.type = capture->type;
59  ret = ioctl(s->fd, VIDIOC_G_FMT, &capture->format);
60  if (ret) {
61  av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_FMT ioctl\n");
62  return ret;
63  }
64 
65  /* 2.1 update the AVCodecContext */
66  avctx->pix_fmt = ff_v4l2_format_v4l2_to_avfmt(capture->format.fmt.pix_mp.pixelformat, AV_CODEC_ID_RAWVIDEO);
67  capture->av_pix_fmt = avctx->pix_fmt;
68 
69  /* 3. set the crop parameters */
70  selection.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
71  selection.r.height = avctx->coded_height;
72  selection.r.width = avctx->coded_width;
73  ret = ioctl(s->fd, VIDIOC_S_SELECTION, &selection);
74  if (!ret) {
75  ret = ioctl(s->fd, VIDIOC_G_SELECTION, &selection);
76  if (ret) {
77  av_log(avctx, AV_LOG_WARNING, "VIDIOC_G_SELECTION ioctl\n");
78  } else {
79  av_log(avctx, AV_LOG_DEBUG, "crop output %dx%d\n", selection.r.width, selection.r.height);
80  /* update the size of the resulting frame */
81  capture->height = selection.r.height;
82  capture->width = selection.r.width;
83  }
84  }
85 
86  /* 4. init the capture context now that we have the capture format */
87  if (!capture->buffers) {
88  ret = ff_v4l2_context_init(capture);
89  if (ret) {
90  av_log(avctx, AV_LOG_ERROR, "can't request capture buffers\n");
91  return AVERROR(ENOMEM);
92  }
93  }
94 
95  /* 5. start the capture process */
96  ret = ff_v4l2_context_set_status(capture, VIDIOC_STREAMON);
97  if (ret) {
98  av_log(avctx, AV_LOG_DEBUG, "VIDIOC_STREAMON, on capture context\n");
99  return ret;
100  }
101 
102  return 0;
103 }
104 
106 {
107  struct v4l2_event_subscription sub;
108  V4L2Context *output = &s->output;
109  int ret;
110 
111  /**
112  * requirements
113  */
114  memset(&sub, 0, sizeof(sub));
115  sub.type = V4L2_EVENT_SOURCE_CHANGE;
116  ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
117  if ( ret < 0) {
118  if (output->height == 0 || output->width == 0) {
119  av_log(s->avctx, AV_LOG_ERROR,
120  "the v4l2 driver does not support VIDIOC_SUBSCRIBE_EVENT\n"
121  "you must provide codec_height and codec_width on input\n");
122  return ret;
123  }
124  }
125 
126  memset(&sub, 0, sizeof(sub));
127  sub.type = V4L2_EVENT_EOS;
128  ret = ioctl(s->fd, VIDIOC_SUBSCRIBE_EVENT, &sub);
129  if (ret < 0)
130  av_log(s->avctx, AV_LOG_WARNING,
131  "the v4l2 driver does not support end of stream VIDIOC_SUBSCRIBE_EVENT\n");
132 
133  return 0;
134 }
135 
137 {
138  V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context;
139  V4L2Context *const capture = &s->capture;
140  V4L2Context *const output = &s->output;
141  int ret;
142 
143  if (!s->buf_pkt.size) {
144  ret = ff_decode_get_packet(avctx, &s->buf_pkt);
145  if (ret < 0) {
146  if (ret == AVERROR(EAGAIN))
147  return ff_v4l2_context_dequeue_frame(capture, frame, 0);
148  else if (ret != AVERROR_EOF)
149  return ret;
150  }
151  }
152 
153  if (s->draining)
154  goto dequeue;
155 
157  if (ret < 0 && ret != AVERROR(EAGAIN))
158  goto fail;
159 
160  /* if EAGAIN don't unref packet and try to enqueue in the next iteration */
161  if (ret != AVERROR(EAGAIN))
162  av_packet_unref(&s->buf_pkt);
163 
164  if (!s->draining) {
165  ret = v4l2_try_start(avctx);
166  if (ret) {
167  /* cant recover */
168  if (ret != AVERROR(ENOMEM))
169  ret = 0;
170  goto fail;
171  }
172  }
173 
174 dequeue:
175  return ff_v4l2_context_dequeue_frame(capture, frame, -1);
176 fail:
177  av_packet_unref(&s->buf_pkt);
178  return ret;
179 }
180 
182 {
183  V4L2Context *capture, *output;
184  V4L2m2mContext *s;
185  V4L2m2mPriv *priv = avctx->priv_data;
186  int ret;
187 
188  ret = ff_v4l2_m2m_create_context(priv, &s);
189  if (ret < 0)
190  return ret;
191 
192  capture = &s->capture;
193  output = &s->output;
194 
195  /* if these dimensions are invalid (ie, 0 or too small) an event will be raised
196  * by the v4l2 driver; this event will trigger a full pipeline reconfig and
197  * the proper values will be retrieved from the kernel driver.
198  */
199  output->height = capture->height = avctx->coded_height;
200  output->width = capture->width = avctx->coded_width;
201 
202  output->av_codec_id = avctx->codec_id;
203  output->av_pix_fmt = AV_PIX_FMT_NONE;
204 
206  capture->av_pix_fmt = avctx->pix_fmt;
207 
208  s->avctx = avctx;
209  ret = ff_v4l2_m2m_codec_init(priv);
210  if (ret) {
211  av_log(avctx, AV_LOG_ERROR, "can't configure decoder\n");
212  return ret;
213  }
214 
215  return v4l2_prepare_decoder(s);
216 }
217 
219 {
220  return ff_v4l2_m2m_codec_end(avctx->priv_data);
221 }
222 
223 #define OFFSET(x) offsetof(V4L2m2mPriv, x)
224 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_DECODING_PARAM
225 
226 static const AVOption options[] = {
228  { "num_capture_buffers", "Number of buffers in the capture context",
229  OFFSET(num_capture_buffers), AV_OPT_TYPE_INT, {.i64 = 20}, 2, INT_MAX, FLAGS },
230  { NULL},
231 };
232 
233 #define M2MDEC_CLASS(NAME) \
234  static const AVClass v4l2_m2m_ ## NAME ## _dec_class = { \
235  .class_name = #NAME "_v4l2m2m_decoder", \
236  .item_name = av_default_item_name, \
237  .option = options, \
238  .version = LIBAVUTIL_VERSION_INT, \
239  };
240 
241 #define M2MDEC(NAME, LONGNAME, CODEC, bsf_name) \
242  M2MDEC_CLASS(NAME) \
243  const FFCodec ff_ ## NAME ## _v4l2m2m_decoder = { \
244  .p.name = #NAME "_v4l2m2m" , \
245  CODEC_LONG_NAME("V4L2 mem2mem " LONGNAME " decoder wrapper"), \
246  .p.type = AVMEDIA_TYPE_VIDEO, \
247  .p.id = CODEC , \
248  .priv_data_size = sizeof(V4L2m2mPriv), \
249  .p.priv_class = &v4l2_m2m_ ## NAME ## _dec_class, \
250  .init = v4l2_decode_init, \
251  FF_CODEC_RECEIVE_FRAME_CB(v4l2_receive_frame), \
252  .close = v4l2_decode_close, \
253  .bsfs = bsf_name, \
254  .p.capabilities = AV_CODEC_CAP_HARDWARE | AV_CODEC_CAP_DELAY | AV_CODEC_CAP_AVOID_PROBING, \
255  .caps_internal = FF_CODEC_CAP_NOT_INIT_THREADSAFE | \
256  FF_CODEC_CAP_INIT_CLEANUP, \
257  .p.wrapper_name = "v4l2m2m", \
258  }
259 
260 M2MDEC(h264, "H.264", AV_CODEC_ID_H264, "h264_mp4toannexb");
261 M2MDEC(hevc, "HEVC", AV_CODEC_ID_HEVC, "hevc_mp4toannexb");
262 M2MDEC(mpeg1, "MPEG1", AV_CODEC_ID_MPEG1VIDEO, NULL);
263 M2MDEC(mpeg2, "MPEG2", AV_CODEC_ID_MPEG2VIDEO, NULL);
264 M2MDEC(mpeg4, "MPEG4", AV_CODEC_ID_MPEG4, NULL);
265 M2MDEC(h263, "H.263", AV_CODEC_ID_H263, NULL);
266 M2MDEC(vc1 , "VC1", AV_CODEC_ID_VC1, NULL);
267 M2MDEC(vp8, "VP8", AV_CODEC_ID_VP8, NULL);
268 M2MDEC(vp9, "VP9", AV_CODEC_ID_VP9, NULL);
ff_v4l2_context_init
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:713
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: packet.c:429
ff_decode_get_packet
int ff_decode_get_packet(AVCodecContext *avctx, AVPacket *pkt)
Called by decoders to get the next packet for decoding.
Definition: decode.c:248
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:215
V4L2Context::av_pix_fmt
enum AVPixelFormat av_pix_fmt
AVPixelFormat corresponding to this buffer context.
Definition: v4l2_context.h:54
AVERROR
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
opt.h
v4l2_decode_close
static av_cold int v4l2_decode_close(AVCodecContext *avctx)
Definition: v4l2_m2m_dec.c:218
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
output
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
Definition: filter_design.txt:225
V4L2Context::av_codec_id
enum AVCodecID av_codec_id
AVCodecID corresponding to this buffer context.
Definition: v4l2_context.h:60
V4L2m2mContext
Definition: v4l2_m2m.h:43
AV_CODEC_ID_RAWVIDEO
@ AV_CODEC_ID_RAWVIDEO
Definition: codec_id.h:65
AV_CODEC_ID_MPEG4
@ AV_CODEC_ID_MPEG4
Definition: codec_id.h:64
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:389
pixdesc.h
AVOption
AVOption.
Definition: opt.h:429
fail
#define fail()
Definition: checkasm.h:188
AVCodecContext::coded_height
int coded_height
Definition: avcodec.h:639
V4L2Context::streamon
int streamon
Whether the stream has been started (VIDIOC_STREAMON has been sent).
Definition: v4l2_context.h:88
OFFSET
#define OFFSET(x)
Definition: v4l2_m2m_dec.c:223
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:209
av_cold
#define av_cold
Definition: attributes.h:90
v4l2_fmt.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
ff_v4l2_format_v4l2_to_avfmt
enum AVPixelFormat ff_v4l2_format_v4l2_to_avfmt(uint32_t v4l2_fmt, enum AVCodecID avcodec)
Definition: v4l2_fmt.c:132
AV_CODEC_ID_VP9
@ AV_CODEC_ID_VP9
Definition: codec_id.h:222
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:230
decode.h
ff_v4l2_m2m_codec_init
int ff_v4l2_m2m_codec_init(V4L2m2mPriv *priv)
Probes the video nodes looking for the required codec capabilities.
Definition: v4l2_m2m.c:290
AV_CODEC_ID_H264
@ AV_CODEC_ID_H264
Definition: codec_id.h:79
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:461
V4L2Context
Definition: v4l2_context.h:37
NULL
#define NULL
Definition: coverity.c:32
V4L2Context::type
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:48
ff_v4l2_context_enqueue_packet
int ff_v4l2_context_enqueue_packet(V4L2Context *ctx, const AVPacket *pkt)
Enqueues a buffer to a V4L2Context from an AVPacket.
Definition: v4l2_context.c:602
ff_v4l2_m2m_create_context
int ff_v4l2_m2m_create_context(V4L2m2mPriv *priv, V4L2m2mContext **s)
Allocate a new context and references for a V4L2 M2M instance.
Definition: v4l2_m2m.c:328
V4L_M2M_DEFAULT_OPTS
#define V4L_M2M_DEFAULT_OPTS
Definition: v4l2_m2m.h:39
options
static const AVOption options[]
Definition: v4l2_m2m_dec.c:226
AV_CODEC_ID_MPEG1VIDEO
@ AV_CODEC_ID_MPEG1VIDEO
Definition: codec_id.h:53
M2MDEC
#define M2MDEC(NAME, LONGNAME, CODEC, bsf_name)
Definition: v4l2_m2m_dec.c:241
v4l2_decode_init
static av_cold int v4l2_decode_init(AVCodecContext *avctx)
Definition: v4l2_m2m_dec.c:181
ff_v4l2_m2m_codec_end
int ff_v4l2_m2m_codec_end(V4L2m2mPriv *priv)
Releases all the codec resources if all AVBufferRefs have been returned to the ctx.
Definition: v4l2_m2m.c:264
V4L2Context::width
int width
Width and height of the frames it produces (in case of a capture context, e.g.
Definition: v4l2_context.h:72
codec_internal.h
FLAGS
#define FLAGS
Definition: v4l2_m2m_dec.c:224
AV_CODEC_ID_H263
@ AV_CODEC_ID_H263
Definition: codec_id.h:56
ff_v4l2_context_dequeue_frame
int ff_v4l2_context_dequeue_frame(V4L2Context *ctx, AVFrame *frame, int timeout)
Dequeues a buffer from a V4L2Context to an AVFrame.
Definition: v4l2_context.c:627
ff_v4l2_context_set_status
int ff_v4l2_context_set_status(V4L2Context *ctx, uint32_t cmd)
Sets the status of a V4L2Context.
Definition: v4l2_context.c:563
V4L2Context::buffers
V4L2Buffer * buffers
Indexed array of V4L2Buffers.
Definition: v4l2_context.h:78
AV_CODEC_ID_HEVC
@ AV_CODEC_ID_HEVC
Definition: codec_id.h:228
AV_CODEC_ID_VC1
@ AV_CODEC_ID_VC1
Definition: codec_id.h:122
v4l2_context.h
AVCodecContext::pix_fmt
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:663
avcodec.h
ret
ret
Definition: filter_design.txt:187
pixfmt.h
frame
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
Definition: filter_design.txt:264
v4l2_receive_frame
static int v4l2_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Definition: v4l2_m2m_dec.c:136
V4L2Context::height
int height
Definition: v4l2_context.h:72
AVCodecContext
main external API structure.
Definition: avcodec.h:451
AV_PIX_FMT_NONE
@ AV_PIX_FMT_NONE
Definition: pixfmt.h:72
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Underlying C type is int.
Definition: opt.h:259
V4L2m2mPriv
Definition: v4l2_m2m.h:71
v4l2_prepare_decoder
static int v4l2_prepare_decoder(V4L2m2mContext *s)
Definition: v4l2_m2m_dec.c:105
AVCodecContext::coded_width
int coded_width
Bitstream width / height, may be different from width/height e.g.
Definition: avcodec.h:639
v4l2_try_start
static int v4l2_try_start(AVCodecContext *avctx)
Definition: v4l2_m2m_dec.c:37
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:478
V4L2Context::format
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:66
v4l2_m2m.h
AV_CODEC_ID_VP8
@ AV_CODEC_ID_VP8
Definition: codec_id.h:192
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AV_CODEC_ID_MPEG2VIDEO
@ AV_CODEC_ID_MPEG2VIDEO
preferred ID for MPEG-1/2 video decoding
Definition: codec_id.h:54