libavcodec/v4l2_buffers.c - third_party/ffmpeg - Git at Google

 /*
  * V4L2 buffer helper functions.
  *
  * Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
  * Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include <linux/videodev2.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <poll.h>
 #include "libavcodec/avcodec.h"
 #include "libavcodec/internal.h"
 #include "v4l2_context.h"
 #include "v4l2_buffers.h"
 #include "v4l2_m2m.h"

 #define USEC_PER_SEC 1000000

 static inline V4L2m2mContext *buf_to_m2mctx(V4L2Buffer *buf)
 {
     return V4L2_TYPE_IS_OUTPUT(buf->context->type) ?
         container_of(buf->context, V4L2m2mContext, output) :
         container_of(buf->context, V4L2m2mContext, capture);
 }

 static inline AVCodecContext *logger(V4L2Buffer *buf)
 {
     return buf_to_m2mctx(buf)->avctx;
 }

 static inline void v4l2_set_pts(V4L2Buffer *out, int64_t pts)
 {
     V4L2m2mContext *s = buf_to_m2mctx(out);
     AVRational v4l2_timebase = { 1, USEC_PER_SEC };
     int64_t v4l2_pts;

     if (pts == AV_NOPTS_VALUE)
         pts = 0;

     /* convert pts to v4l2 timebase */
     v4l2_pts = av_rescale_q(pts, s->avctx->time_base, v4l2_timebase);
     out->buf.timestamp.tv_usec = v4l2_pts % USEC_PER_SEC;
     out->buf.timestamp.tv_sec = v4l2_pts / USEC_PER_SEC;
 }

 static inline uint64_t v4l2_get_pts(V4L2Buffer *avbuf)
 {
     V4L2m2mContext *s = buf_to_m2mctx(avbuf);
     AVRational v4l2_timebase = { 1, USEC_PER_SEC };
     int64_t v4l2_pts;

     /* convert pts back to encoder timebase */
     v4l2_pts = (int64_t)avbuf->buf.timestamp.tv_sec * USEC_PER_SEC +
                         avbuf->buf.timestamp.tv_usec;

     return av_rescale_q(v4l2_pts, v4l2_timebase, s->avctx->time_base);
 }

 static enum AVColorPrimaries v4l2_get_color_primaries(V4L2Buffer *buf)
 {
     enum v4l2_ycbcr_encoding ycbcr;
     enum v4l2_colorspace cs;

     cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.colorspace :
         buf->context->format.fmt.pix.colorspace;

     ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.ycbcr_enc:
         buf->context->format.fmt.pix.ycbcr_enc;

     switch(ycbcr) {
     case V4L2_YCBCR_ENC_XV709:
     case V4L2_YCBCR_ENC_709: return AVCOL_PRI_BT709;
     case V4L2_YCBCR_ENC_XV601:
     case V4L2_YCBCR_ENC_601:return AVCOL_PRI_BT470M;
     default:
         break;
     }

     switch(cs) {
     case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_PRI_BT470BG;
     case V4L2_COLORSPACE_SMPTE170M: return AVCOL_PRI_SMPTE170M;
     case V4L2_COLORSPACE_SMPTE240M: return AVCOL_PRI_SMPTE240M;
     case V4L2_COLORSPACE_BT2020: return AVCOL_PRI_BT2020;
     default:
         break;
     }

     return AVCOL_PRI_UNSPECIFIED;
 }

 static enum AVColorRange v4l2_get_color_range(V4L2Buffer *buf)
 {
     enum v4l2_quantization qt;

     qt = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.quantization :
         buf->context->format.fmt.pix.quantization;

     switch (qt) {
     case V4L2_QUANTIZATION_LIM_RANGE: return AVCOL_RANGE_MPEG;
     case V4L2_QUANTIZATION_FULL_RANGE: return AVCOL_RANGE_JPEG;
     default:
         break;
     }

      return AVCOL_RANGE_UNSPECIFIED;
 }

 static enum AVColorSpace v4l2_get_color_space(V4L2Buffer *buf)
 {
     enum v4l2_ycbcr_encoding ycbcr;
     enum v4l2_colorspace cs;

     cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.colorspace :
         buf->context->format.fmt.pix.colorspace;

     ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.ycbcr_enc:
         buf->context->format.fmt.pix.ycbcr_enc;

     switch(cs) {
     case V4L2_COLORSPACE_SRGB: return AVCOL_SPC_RGB;
     case V4L2_COLORSPACE_REC709: return AVCOL_SPC_BT709;
     case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_SPC_FCC;
     case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_SPC_BT470BG;
     case V4L2_COLORSPACE_SMPTE170M: return AVCOL_SPC_SMPTE170M;
     case V4L2_COLORSPACE_SMPTE240M: return AVCOL_SPC_SMPTE240M;
     case V4L2_COLORSPACE_BT2020:
         if (ycbcr == V4L2_YCBCR_ENC_BT2020_CONST_LUM)
             return AVCOL_SPC_BT2020_CL;
         else
              return AVCOL_SPC_BT2020_NCL;
     default:
         break;
     }

     return AVCOL_SPC_UNSPECIFIED;
 }

 static enum AVColorTransferCharacteristic v4l2_get_color_trc(V4L2Buffer *buf)
 {
     enum v4l2_ycbcr_encoding ycbcr;
     enum v4l2_xfer_func xfer;
     enum v4l2_colorspace cs;

     cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.colorspace :
         buf->context->format.fmt.pix.colorspace;

     ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.ycbcr_enc:
         buf->context->format.fmt.pix.ycbcr_enc;

     xfer = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
         buf->context->format.fmt.pix_mp.xfer_func:
         buf->context->format.fmt.pix.xfer_func;

     switch (xfer) {
     case V4L2_XFER_FUNC_709: return AVCOL_TRC_BT709;
     case V4L2_XFER_FUNC_SRGB: return AVCOL_TRC_IEC61966_2_1;
     default:
         break;
     }

     switch (cs) {
     case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_TRC_GAMMA22;
     case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_TRC_GAMMA28;
     case V4L2_COLORSPACE_SMPTE170M: return AVCOL_TRC_SMPTE170M;
     case V4L2_COLORSPACE_SMPTE240M: return AVCOL_TRC_SMPTE240M;
     default:
         break;
     }

     switch (ycbcr) {
     case V4L2_YCBCR_ENC_XV709:
     case V4L2_YCBCR_ENC_XV601: return AVCOL_TRC_BT1361_ECG;
     default:
         break;
     }

     return AVCOL_TRC_UNSPECIFIED;
 }

 static void v4l2_free_buffer(void *opaque, uint8_t *unused)
 {
     V4L2Buffer* avbuf = opaque;
     V4L2m2mContext *s = buf_to_m2mctx(avbuf);

     if (atomic_fetch_sub(&avbuf->context_refcount, 1) == 1) {
         atomic_fetch_sub_explicit(&s->refcount, 1, memory_order_acq_rel);

         if (s->reinit) {
             if (!atomic_load(&s->refcount))
                 sem_post(&s->refsync);
         } else {
             if (s->draining) {
                 /* no need to queue more buffers to the driver */
                 avbuf->status = V4L2BUF_AVAILABLE;
             }
             else if (avbuf->context->streamon)
                 ff_v4l2_buffer_enqueue(avbuf);
         }

         av_buffer_unref(&avbuf->context_ref);
     }
 }

 static int v4l2_buf_to_bufref(V4L2Buffer *in, int plane, AVBufferRef **buf)
 {
     V4L2m2mContext *s = buf_to_m2mctx(in);

     if (plane >= in->num_planes)
         return AVERROR(EINVAL);

     /* even though most encoders return 0 in data_offset encoding vp8 does require this value */
     *buf = av_buffer_create((char *)in->plane_info[plane].mm_addr + in->planes[plane].data_offset,
                             in->plane_info[plane].length, v4l2_free_buffer, in, 0);
     if (!*buf)
         return AVERROR(ENOMEM);

     if (in->context_ref)
         atomic_fetch_add(&in->context_refcount, 1);
     else {
         in->context_ref = av_buffer_ref(s->self_ref);
         if (!in->context_ref) {
             av_buffer_unref(buf);
             return AVERROR(ENOMEM);
         }
         in->context_refcount = 1;
     }

     in->status = V4L2BUF_RET_USER;
     atomic_fetch_add_explicit(&s->refcount, 1, memory_order_relaxed);

     return 0;
 }

 static int v4l2_bufref_to_buf(V4L2Buffer *out, int plane, const uint8_t* data, int size, AVBufferRef* bref)
 {
     unsigned int bytesused, length;

     if (plane >= out->num_planes)
         return AVERROR(EINVAL);

     bytesused = FFMIN(size, out->plane_info[plane].length);
     length = out->plane_info[plane].length;

     memcpy(out->plane_info[plane].mm_addr, data, FFMIN(size, out->plane_info[plane].length));

     if (V4L2_TYPE_IS_MULTIPLANAR(out->buf.type)) {
         out->planes[plane].bytesused = bytesused;
         out->planes[plane].length = length;
     } else {
         out->buf.bytesused = bytesused;
         out->buf.length = length;
     }

     return 0;
 }

 /******************************************************************************
  *
  *              V4L2uffer interface
  *
  ******************************************************************************/

 int ff_v4l2_buffer_avframe_to_buf(const AVFrame *frame, V4L2Buffer* out)
 {
     int i, ret;

     for(i = 0; i < out->num_planes; i++) {
         ret = v4l2_bufref_to_buf(out, i, frame->buf[i]->data, frame->buf[i]->size, frame->buf[i]);
         if (ret)
             return ret;
     }

     v4l2_set_pts(out, frame->pts);

     return 0;
 }

 int ff_v4l2_buffer_buf_to_avframe(AVFrame *frame, V4L2Buffer *avbuf)
 {
     V4L2m2mContext *s = buf_to_m2mctx(avbuf);
     int i, ret;

     av_frame_unref(frame);

     /* 1. get references to the actual data */
     for (i = 0; i < avbuf->num_planes; i++) {
         ret = v4l2_buf_to_bufref(avbuf, i, &frame->buf[i]);
         if (ret)
             return ret;

         frame->linesize[i] = avbuf->plane_info[i].bytesperline;
         frame->data[i] = frame->buf[i]->data;
     }

     /* 1.1 fixup special cases */
     switch (avbuf->context->av_pix_fmt) {
     case AV_PIX_FMT_NV12:
         if (avbuf->num_planes > 1)
             break;
         frame->linesize[1] = avbuf->plane_info[0].bytesperline;
         frame->data[1] = frame->buf[0]->data + avbuf->plane_info[0].bytesperline * avbuf->context->format.fmt.pix_mp.height;
         break;
     default:
         break;
     }

     /* 2. get frame information */
     frame->key_frame = !!(avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME);
     frame->format = avbuf->context->av_pix_fmt;
     frame->color_primaries = v4l2_get_color_primaries(avbuf);
     frame->colorspace = v4l2_get_color_space(avbuf);
     frame->color_range = v4l2_get_color_range(avbuf);
     frame->color_trc = v4l2_get_color_trc(avbuf);
     frame->pts = v4l2_get_pts(avbuf);

     /* these two values are updated also during re-init in v4l2_process_driver_event */
     frame->height = s->output.height;
     frame->width = s->output.width;

     /* 3. report errors upstream */
     if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
         av_log(logger(avbuf), AV_LOG_ERROR, "%s: driver decode error\n", avbuf->context->name);
         frame->decode_error_flags |= FF_DECODE_ERROR_INVALID_BITSTREAM;
     }

     return 0;
 }

 int ff_v4l2_buffer_buf_to_avpkt(AVPacket *pkt, V4L2Buffer *avbuf)
 {
     int ret;

     av_packet_unref(pkt);
     ret = v4l2_buf_to_bufref(avbuf, 0, &pkt->buf);
     if (ret)
         return ret;

     pkt->size = V4L2_TYPE_IS_MULTIPLANAR(avbuf->buf.type) ? avbuf->buf.m.planes[0].bytesused : avbuf->buf.bytesused;
     pkt->data = pkt->buf->data;

     if (avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME)
         pkt->flags |= AV_PKT_FLAG_KEY;

     if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
         av_log(logger(avbuf), AV_LOG_ERROR, "%s driver encode error\n", avbuf->context->name);
         pkt->flags |= AV_PKT_FLAG_CORRUPT;
     }

     pkt->dts = pkt->pts = v4l2_get_pts(avbuf);

     return 0;
 }

 int ff_v4l2_buffer_avpkt_to_buf(const AVPacket *pkt, V4L2Buffer *out)
 {
     int ret;

     ret = v4l2_bufref_to_buf(out, 0, pkt->data, pkt->size, pkt->buf);
     if (ret)
         return ret;

     v4l2_set_pts(out, pkt->pts);

     if (pkt->flags & AV_PKT_FLAG_KEY)
         out->flags = V4L2_BUF_FLAG_KEYFRAME;

     return 0;
 }

 int ff_v4l2_buffer_initialize(V4L2Buffer* avbuf, int index)
 {
     V4L2Context *ctx = avbuf->context;
     int ret, i;

     avbuf->buf.memory = V4L2_MEMORY_MMAP;
     avbuf->buf.type = ctx->type;
     avbuf->buf.index = index;

     if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
         avbuf->buf.length = VIDEO_MAX_PLANES;
         avbuf->buf.m.planes = avbuf->planes;
     }

     ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QUERYBUF, &avbuf->buf);
     if (ret < 0)
         return AVERROR(errno);

     if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
         avbuf->num_planes = 0;
         for (;;) {
             /* in MP, the V4L2 API states that buf.length means num_planes */
             if (avbuf->num_planes >= avbuf->buf.length)
                 break;
             if (avbuf->buf.m.planes[avbuf->num_planes].length)
                 avbuf->num_planes++;
         }
     } else
         avbuf->num_planes = 1;

     for (i = 0; i < avbuf->num_planes; i++) {

         avbuf->plane_info[i].bytesperline = V4L2_TYPE_IS_MULTIPLANAR(ctx->type) ?
             ctx->format.fmt.pix_mp.plane_fmt[i].bytesperline :
             ctx->format.fmt.pix.bytesperline;

         if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
             avbuf->plane_info[i].length = avbuf->buf.m.planes[i].length;
             avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.m.planes[i].length,
                                            PROT_READ | PROT_WRITE, MAP_SHARED,
                                            buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.planes[i].m.mem_offset);
         } else {
             avbuf->plane_info[i].length = avbuf->buf.length;
             avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.length,
                                           PROT_READ | PROT_WRITE, MAP_SHARED,
                                           buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.offset);
         }

         if (avbuf->plane_info[i].mm_addr == MAP_FAILED)
             return AVERROR(ENOMEM);
     }

     avbuf->status = V4L2BUF_AVAILABLE;

     if (V4L2_TYPE_IS_OUTPUT(ctx->type))
         return 0;

     if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
         avbuf->buf.m.planes = avbuf->planes;
         avbuf->buf.length   = avbuf->num_planes;

     } else {
         avbuf->buf.bytesused = avbuf->planes[0].bytesused;
         avbuf->buf.length    = avbuf->planes[0].length;
     }

     return ff_v4l2_buffer_enqueue(avbuf);
 }

 int ff_v4l2_buffer_enqueue(V4L2Buffer* avbuf)
 {
     int ret;

     avbuf->buf.flags = avbuf->flags;

     ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QBUF, &avbuf->buf);
     if (ret < 0)
         return AVERROR(errno);

     avbuf->status = V4L2BUF_IN_DRIVER;

     return 0;
 }
	/*
	* V4L2 buffer helper functions.
	*
	* Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
	* Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include <linux/videodev2.h>
	#include <sys/ioctl.h>
	#include <sys/mman.h>
	#include <unistd.h>
	#include <fcntl.h>
	#include <poll.h>
	#include "libavcodec/avcodec.h"
	#include "libavcodec/internal.h"
	#include "v4l2_context.h"
	#include "v4l2_buffers.h"
	#include "v4l2_m2m.h"

	#define USEC_PER_SEC 1000000

	static inline V4L2m2mContext buf_to_m2mctx(V4L2Buffer buf)
	{
	return V4L2_TYPE_IS_OUTPUT(buf->context->type) ?
	container_of(buf->context, V4L2m2mContext, output) :
	container_of(buf->context, V4L2m2mContext, capture);
	}

	static inline AVCodecContext logger(V4L2Buffer buf)
	{
	return buf_to_m2mctx(buf)->avctx;
	}

	static inline void v4l2_set_pts(V4L2Buffer *out, int64_t pts)
	{
	V4L2m2mContext *s = buf_to_m2mctx(out);
	AVRational v4l2_timebase = { 1, USEC_PER_SEC };
	int64_t v4l2_pts;

	if (pts == AV_NOPTS_VALUE)
	pts = 0;

	/* convert pts to v4l2 timebase */
	v4l2_pts = av_rescale_q(pts, s->avctx->time_base, v4l2_timebase);
	out->buf.timestamp.tv_usec = v4l2_pts % USEC_PER_SEC;
	out->buf.timestamp.tv_sec = v4l2_pts / USEC_PER_SEC;
	}

	static inline uint64_t v4l2_get_pts(V4L2Buffer *avbuf)
	{
	V4L2m2mContext *s = buf_to_m2mctx(avbuf);
	AVRational v4l2_timebase = { 1, USEC_PER_SEC };
	int64_t v4l2_pts;

	/* convert pts back to encoder timebase */
	v4l2_pts = (int64_t)avbuf->buf.timestamp.tv_sec * USEC_PER_SEC +
	avbuf->buf.timestamp.tv_usec;

	return av_rescale_q(v4l2_pts, v4l2_timebase, s->avctx->time_base);
	}

	static enum AVColorPrimaries v4l2_get_color_primaries(V4L2Buffer *buf)
	{
	enum v4l2_ycbcr_encoding ycbcr;
	enum v4l2_colorspace cs;

	cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.colorspace :
	buf->context->format.fmt.pix.colorspace;

	ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.ycbcr_enc:
	buf->context->format.fmt.pix.ycbcr_enc;

	switch(ycbcr) {
	case V4L2_YCBCR_ENC_XV709:
	case V4L2_YCBCR_ENC_709: return AVCOL_PRI_BT709;
	case V4L2_YCBCR_ENC_XV601:
	case V4L2_YCBCR_ENC_601:return AVCOL_PRI_BT470M;
	default:
	break;
	}

	switch(cs) {
	case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_PRI_BT470BG;
	case V4L2_COLORSPACE_SMPTE170M: return AVCOL_PRI_SMPTE170M;
	case V4L2_COLORSPACE_SMPTE240M: return AVCOL_PRI_SMPTE240M;
	case V4L2_COLORSPACE_BT2020: return AVCOL_PRI_BT2020;
	default:
	break;
	}

	return AVCOL_PRI_UNSPECIFIED;
	}

	static enum AVColorRange v4l2_get_color_range(V4L2Buffer *buf)
	{
	enum v4l2_quantization qt;

	qt = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.quantization :
	buf->context->format.fmt.pix.quantization;

	switch (qt) {
	case V4L2_QUANTIZATION_LIM_RANGE: return AVCOL_RANGE_MPEG;
	case V4L2_QUANTIZATION_FULL_RANGE: return AVCOL_RANGE_JPEG;
	default:
	break;
	}

	return AVCOL_RANGE_UNSPECIFIED;
	}

	static enum AVColorSpace v4l2_get_color_space(V4L2Buffer *buf)
	{
	enum v4l2_ycbcr_encoding ycbcr;
	enum v4l2_colorspace cs;

	cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.colorspace :
	buf->context->format.fmt.pix.colorspace;

	ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.ycbcr_enc:
	buf->context->format.fmt.pix.ycbcr_enc;

	switch(cs) {
	case V4L2_COLORSPACE_SRGB: return AVCOL_SPC_RGB;
	case V4L2_COLORSPACE_REC709: return AVCOL_SPC_BT709;
	case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_SPC_FCC;
	case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_SPC_BT470BG;
	case V4L2_COLORSPACE_SMPTE170M: return AVCOL_SPC_SMPTE170M;
	case V4L2_COLORSPACE_SMPTE240M: return AVCOL_SPC_SMPTE240M;
	case V4L2_COLORSPACE_BT2020:
	if (ycbcr == V4L2_YCBCR_ENC_BT2020_CONST_LUM)
	return AVCOL_SPC_BT2020_CL;
	else
	return AVCOL_SPC_BT2020_NCL;
	default:
	break;
	}

	return AVCOL_SPC_UNSPECIFIED;
	}

	static enum AVColorTransferCharacteristic v4l2_get_color_trc(V4L2Buffer *buf)
	{
	enum v4l2_ycbcr_encoding ycbcr;
	enum v4l2_xfer_func xfer;
	enum v4l2_colorspace cs;

	cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.colorspace :
	buf->context->format.fmt.pix.colorspace;

	ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.ycbcr_enc:
	buf->context->format.fmt.pix.ycbcr_enc;

	xfer = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
	buf->context->format.fmt.pix_mp.xfer_func:
	buf->context->format.fmt.pix.xfer_func;

	switch (xfer) {
	case V4L2_XFER_FUNC_709: return AVCOL_TRC_BT709;
	case V4L2_XFER_FUNC_SRGB: return AVCOL_TRC_IEC61966_2_1;
	default:
	break;
	}

	switch (cs) {
	case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_TRC_GAMMA22;
	case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_TRC_GAMMA28;
	case V4L2_COLORSPACE_SMPTE170M: return AVCOL_TRC_SMPTE170M;
	case V4L2_COLORSPACE_SMPTE240M: return AVCOL_TRC_SMPTE240M;
	default:
	break;
	}

	switch (ycbcr) {
	case V4L2_YCBCR_ENC_XV709:
	case V4L2_YCBCR_ENC_XV601: return AVCOL_TRC_BT1361_ECG;
	default:
	break;
	}

	return AVCOL_TRC_UNSPECIFIED;
	}

	static void v4l2_free_buffer(void opaque, uint8_t unused)
	{
	V4L2Buffer* avbuf = opaque;
	V4L2m2mContext *s = buf_to_m2mctx(avbuf);

	if (atomic_fetch_sub(&avbuf->context_refcount, 1) == 1) {
	atomic_fetch_sub_explicit(&s->refcount, 1, memory_order_acq_rel);

	if (s->reinit) {
	if (!atomic_load(&s->refcount))
	sem_post(&s->refsync);
	} else {
	if (s->draining) {
	/* no need to queue more buffers to the driver */
	avbuf->status = V4L2BUF_AVAILABLE;
	}
	else if (avbuf->context->streamon)
	ff_v4l2_buffer_enqueue(avbuf);
	}

	av_buffer_unref(&avbuf->context_ref);
	}
	}

	static int v4l2_buf_to_bufref(V4L2Buffer in, int plane, AVBufferRef *buf)
	{
	V4L2m2mContext *s = buf_to_m2mctx(in);

	if (plane >= in->num_planes)
	return AVERROR(EINVAL);

	/* even though most encoders return 0 in data_offset encoding vp8 does require this value */
	buf = av_buffer_create((char )in->plane_info[plane].mm_addr + in->planes[plane].data_offset,
	in->plane_info[plane].length, v4l2_free_buffer, in, 0);
	if (!*buf)
	return AVERROR(ENOMEM);

	if (in->context_ref)
	atomic_fetch_add(&in->context_refcount, 1);
	else {
	in->context_ref = av_buffer_ref(s->self_ref);
	if (!in->context_ref) {
	av_buffer_unref(buf);
	return AVERROR(ENOMEM);
	}
	in->context_refcount = 1;
	}

	in->status = V4L2BUF_RET_USER;
	atomic_fetch_add_explicit(&s->refcount, 1, memory_order_relaxed);

	return 0;
	}

	static int v4l2_bufref_to_buf(V4L2Buffer out, int plane, const uint8_t data, int size, AVBufferRef* bref)
	{
	unsigned int bytesused, length;

	if (plane >= out->num_planes)
	return AVERROR(EINVAL);

	bytesused = FFMIN(size, out->plane_info[plane].length);
	length = out->plane_info[plane].length;

	memcpy(out->plane_info[plane].mm_addr, data, FFMIN(size, out->plane_info[plane].length));

	if (V4L2_TYPE_IS_MULTIPLANAR(out->buf.type)) {
	out->planes[plane].bytesused = bytesused;
	out->planes[plane].length = length;
	} else {
	out->buf.bytesused = bytesused;
	out->buf.length = length;
	}

	return 0;
	}

	/******************************************************************************
	*
	* V4L2uffer interface
	*
	******************************************************************************/

	int ff_v4l2_buffer_avframe_to_buf(const AVFrame frame, V4L2Buffer out)
	{
	int i, ret;

	for(i = 0; i < out->num_planes; i++) {
	ret = v4l2_bufref_to_buf(out, i, frame->buf[i]->data, frame->buf[i]->size, frame->buf[i]);
	if (ret)
	return ret;
	}

	v4l2_set_pts(out, frame->pts);

	return 0;
	}

	int ff_v4l2_buffer_buf_to_avframe(AVFrame frame, V4L2Buffer avbuf)
	{
	V4L2m2mContext *s = buf_to_m2mctx(avbuf);
	int i, ret;

	av_frame_unref(frame);

	/* 1. get references to the actual data */
	for (i = 0; i < avbuf->num_planes; i++) {
	ret = v4l2_buf_to_bufref(avbuf, i, &frame->buf[i]);
	if (ret)
	return ret;

	frame->linesize[i] = avbuf->plane_info[i].bytesperline;
	frame->data[i] = frame->buf[i]->data;
	}

	/* 1.1 fixup special cases */
	switch (avbuf->context->av_pix_fmt) {
	case AV_PIX_FMT_NV12:
	if (avbuf->num_planes > 1)
	break;
	frame->linesize[1] = avbuf->plane_info[0].bytesperline;
	frame->data[1] = frame->buf[0]->data + avbuf->plane_info[0].bytesperline * avbuf->context->format.fmt.pix_mp.height;
	break;
	default:
	break;
	}

	/* 2. get frame information */
	frame->key_frame = !!(avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME);
	frame->format = avbuf->context->av_pix_fmt;
	frame->color_primaries = v4l2_get_color_primaries(avbuf);
	frame->colorspace = v4l2_get_color_space(avbuf);
	frame->color_range = v4l2_get_color_range(avbuf);
	frame->color_trc = v4l2_get_color_trc(avbuf);
	frame->pts = v4l2_get_pts(avbuf);

	/* these two values are updated also during re-init in v4l2_process_driver_event */
	frame->height = s->output.height;
	frame->width = s->output.width;

	/* 3. report errors upstream */
	if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
	av_log(logger(avbuf), AV_LOG_ERROR, "%s: driver decode error\n", avbuf->context->name);
	frame->decode_error_flags \|= FF_DECODE_ERROR_INVALID_BITSTREAM;
	}

	return 0;
	}

	int ff_v4l2_buffer_buf_to_avpkt(AVPacket pkt, V4L2Buffer avbuf)
	{
	int ret;

	av_packet_unref(pkt);
	ret = v4l2_buf_to_bufref(avbuf, 0, &pkt->buf);
	if (ret)
	return ret;

	pkt->size = V4L2_TYPE_IS_MULTIPLANAR(avbuf->buf.type) ? avbuf->buf.m.planes[0].bytesused : avbuf->buf.bytesused;
	pkt->data = pkt->buf->data;

	if (avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME)
	pkt->flags \|= AV_PKT_FLAG_KEY;

	if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
	av_log(logger(avbuf), AV_LOG_ERROR, "%s driver encode error\n", avbuf->context->name);
	pkt->flags \|= AV_PKT_FLAG_CORRUPT;
	}

	pkt->dts = pkt->pts = v4l2_get_pts(avbuf);

	return 0;
	}

	int ff_v4l2_buffer_avpkt_to_buf(const AVPacket pkt, V4L2Buffer out)
	{
	int ret;

	ret = v4l2_bufref_to_buf(out, 0, pkt->data, pkt->size, pkt->buf);
	if (ret)
	return ret;

	v4l2_set_pts(out, pkt->pts);

	if (pkt->flags & AV_PKT_FLAG_KEY)
	out->flags = V4L2_BUF_FLAG_KEYFRAME;

	return 0;
	}

	int ff_v4l2_buffer_initialize(V4L2Buffer* avbuf, int index)
	{
	V4L2Context *ctx = avbuf->context;
	int ret, i;

	avbuf->buf.memory = V4L2_MEMORY_MMAP;
	avbuf->buf.type = ctx->type;
	avbuf->buf.index = index;

	if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
	avbuf->buf.length = VIDEO_MAX_PLANES;
	avbuf->buf.m.planes = avbuf->planes;
	}

	ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QUERYBUF, &avbuf->buf);
	if (ret < 0)
	return AVERROR(errno);

	if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
	avbuf->num_planes = 0;
	for (;;) {
	/* in MP, the V4L2 API states that buf.length means num_planes */
	if (avbuf->num_planes >= avbuf->buf.length)
	break;
	if (avbuf->buf.m.planes[avbuf->num_planes].length)
	avbuf->num_planes++;
	}
	} else
	avbuf->num_planes = 1;

	for (i = 0; i < avbuf->num_planes; i++) {

	avbuf->plane_info[i].bytesperline = V4L2_TYPE_IS_MULTIPLANAR(ctx->type) ?
	ctx->format.fmt.pix_mp.plane_fmt[i].bytesperline :
	ctx->format.fmt.pix.bytesperline;

	if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
	avbuf->plane_info[i].length = avbuf->buf.m.planes[i].length;
	avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.m.planes[i].length,
	PROT_READ \| PROT_WRITE, MAP_SHARED,
	buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.planes[i].m.mem_offset);
	} else {
	avbuf->plane_info[i].length = avbuf->buf.length;
	avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.length,
	PROT_READ \| PROT_WRITE, MAP_SHARED,
	buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.offset);
	}

	if (avbuf->plane_info[i].mm_addr == MAP_FAILED)
	return AVERROR(ENOMEM);
	}

	avbuf->status = V4L2BUF_AVAILABLE;

	if (V4L2_TYPE_IS_OUTPUT(ctx->type))
	return 0;

	if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
	avbuf->buf.m.planes = avbuf->planes;
	avbuf->buf.length = avbuf->num_planes;

	} else {
	avbuf->buf.bytesused = avbuf->planes[0].bytesused;
	avbuf->buf.length = avbuf->planes[0].length;
	}

	return ff_v4l2_buffer_enqueue(avbuf);
	}

	int ff_v4l2_buffer_enqueue(V4L2Buffer* avbuf)
	{
	int ret;

	avbuf->buf.flags = avbuf->flags;

	ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QBUF, &avbuf->buf);
	if (ret < 0)
	return AVERROR(errno);

	avbuf->status = V4L2BUF_IN_DRIVER;

	return 0;
	}