[FFmpeg-devel,2/5] avcodec: add common V4L2 request API code

diff --git a/configure b/configure
index 10cf61007b..fac85bfab4 100755
--- a/configure
+++ b/configure
@@ -278,6 +278,7 @@  External library support:
                            if openssl, gnutls or mbedtls is not used [no]
   --enable-libtwolame      enable MP2 encoding via libtwolame [no]
   --enable-libuavs3d       enable AVS3 decoding via libuavs3d [no]
+  --enable-libudev         enable libudev [no]
   --enable-libv4l2         enable libv4l2/v4l-utils [no]
   --enable-libvidstab      enable video stabilization using vid.stab [no]
   --enable-libvmaf         enable vmaf filter via libvmaf [no]
@@ -345,6 +346,7 @@  External library support:
   --enable-omx-rpi         enable OpenMAX IL code for Raspberry Pi [no]
   --enable-rkmpp           enable Rockchip Media Process Platform code [no]
   --disable-v4l2-m2m       disable V4L2 mem2mem code [autodetect]
+  --enable-v4l2-request    enable V4L2 request API code [no]
   --disable-vaapi          disable Video Acceleration API (mainly Unix/Intel) code [autodetect]
   --disable-vdpau          disable Nvidia Video Decode and Presentation API for Unix code [autodetect]
   --disable-videotoolbox   disable VideoToolbox code [autodetect]
@@ -1812,6 +1814,7 @@  EXTERNAL_LIBRARY_LIST="
     libtheora
     libtwolame
     libuavs3d
+    libudev
     libv4l2
     libvmaf
     libvorbis
@@ -1866,6 +1869,7 @@  HWACCEL_LIBRARY_LIST="
     mmal
     omx
     opencl
+    v4l2_request
     vulkan
 "
 
@@ -2913,6 +2917,7 @@  d3d11va_deps="dxva_h ID3D11VideoDecoder ID3D11VideoContext"
 dxva2_deps="dxva2api_h DXVA2_ConfigPictureDecode ole32 user32"
 ffnvcodec_deps_any="libdl LoadLibrary"
 nvdec_deps="ffnvcodec"
+v4l2_request_deps="linux_videodev2_h linux_media_h v4l2_timeval_to_ns libdrm libudev"
 vaapi_x11_deps="xlib"
 videotoolbox_hwaccel_deps="videotoolbox pthreads"
 videotoolbox_hwaccel_extralibs="-framework QuartzCore"
@@ -6423,6 +6428,7 @@  enabled libtwolame        && require libtwolame twolame.h twolame_init -ltwolame
                              { check_lib libtwolame twolame.h twolame_encode_buffer_float32_interleaved -ltwolame ||
                                die "ERROR: libtwolame must be installed and version must be >= 0.3.10"; }
 enabled libuavs3d         && require_pkg_config libuavs3d "uavs3d >= 1.1.41" uavs3d.h uavs3d_decode
+enabled libudev           && require_pkg_config libudev libudev libudev.h udev_new
 enabled libv4l2           && require_pkg_config libv4l2 libv4l2 libv4l2.h v4l2_ioctl
 enabled libvidstab        && require_pkg_config libvidstab "vidstab >= 0.98" vid.stab/libvidstab.h vsMotionDetectInit
 enabled libvmaf           && require_pkg_config libvmaf "libvmaf >= 1.5.2" libvmaf.h compute_vmaf
@@ -6521,6 +6527,10 @@  enabled rkmpp             && { require_pkg_config rkmpp rockchip_mpp  rockchip/r
                                { enabled libdrm ||
                                  die "ERROR: rkmpp requires --enable-libdrm"; }
                              }
+enabled v4l2_request      && { enabled libdrm ||
+                               die "ERROR: v4l2-request requires --enable-libdrm"; } &&
+                             { enabled libudev ||
+                               die "ERROR: v4l2-request requires --enable-libudev"; }
 enabled vapoursynth       && require_pkg_config vapoursynth "vapoursynth-script >= 42" VSScript.h vsscript_init
 
 
@@ -6602,6 +6612,8 @@  if enabled v4l2_m2m; then
     check_cc vp9_v4l2_m2m linux/videodev2.h "int i = V4L2_PIX_FMT_VP9;"
 fi
 
+check_func_headers "linux/media.h linux/videodev2.h" v4l2_timeval_to_ns
+
 check_headers sys/videoio.h
 test_code cc sys/videoio.h "struct v4l2_frmsizeenum vfse; vfse.discrete.width = 0;" && enable_sanitized struct_v4l2_frmivalenum_discrete
 
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 9b370ffc44..2fafc4e028 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -155,6 +155,7 @@  OBJS-$(CONFIG_VP3DSP)                  += vp3dsp.o
 OBJS-$(CONFIG_VP56DSP)                 += vp56dsp.o
 OBJS-$(CONFIG_VP8DSP)                  += vp8dsp.o
 OBJS-$(CONFIG_V4L2_M2M)                += v4l2_m2m.o v4l2_context.o v4l2_buffers.o v4l2_fmt.o
+OBJS-$(CONFIG_V4L2_REQUEST)            += v4l2_request.o
 OBJS-$(CONFIG_WMA_FREQS)               += wma_freqs.o
 OBJS-$(CONFIG_WMV2DSP)                 += wmv2dsp.o
 
diff --git a/libavcodec/hwconfig.h b/libavcodec/hwconfig.h
index f421dc909f..ee78d8ab8e 100644
--- a/libavcodec/hwconfig.h
+++ b/libavcodec/hwconfig.h
@@ -80,6 +80,8 @@  typedef struct AVCodecHWConfigInternal {
     HW_CONFIG_HWACCEL(0, 0, 1, D3D11VA_VLD,  NONE,         ff_ ## codec ## _d3d11va_hwaccel)
 #define HWACCEL_XVMC(codec) \
     HW_CONFIG_HWACCEL(0, 0, 1, XVMC,         NONE,         ff_ ## codec ## _xvmc_hwaccel)
+#define HWACCEL_V4L2REQUEST(codec) \
+    HW_CONFIG_HWACCEL(1, 0, 0, DRM_PRIME,    DRM,          ff_ ## codec ## _v4l2request_hwaccel)
 
 #define HW_CONFIG_ENCODER(device, frames, ad_hoc, format, device_type_) \
     &(const AVCodecHWConfigInternal) { \
diff --git a/libavcodec/v4l2_request.c b/libavcodec/v4l2_request.c
new file mode 100644
index 0000000000..a85f522c18
--- /dev/null
+++ b/libavcodec/v4l2_request.c
@@ -0,0 +1,987 @@ 
+/*
+ * 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 <drm_fourcc.h>
+#include <linux/media.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <sys/sysmacros.h>
+#include <libudev.h>
+
+#include "decode.h"
+#include "internal.h"
+#include "v4l2_request.h"
+
+#define OUTPUT_BUFFER_PADDING_SIZE (AV_INPUT_BUFFER_PADDING_SIZE * 4)
+
+uint64_t ff_v4l2_request_get_capture_timestamp(AVFrame *frame)
+{
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)frame->data[0];
+    return req ? v4l2_timeval_to_ns(&req->capture.buffer.timestamp) : 0;
+}
+
+int ff_v4l2_request_reset_frame(AVCodecContext *avctx, AVFrame *frame)
+{
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)frame->data[0];
+    memset(&req->drm, 0, sizeof(AVDRMFrameDescriptor));
+    req->output.used = 0;
+    return 0;
+}
+
+int ff_v4l2_request_append_output_buffer(AVCodecContext *avctx, AVFrame *frame, const uint8_t *data, uint32_t size)
+{
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)frame->data[0];
+    if (req->output.used + size + OUTPUT_BUFFER_PADDING_SIZE <= req->output.size) {
+        memcpy(req->output.addr + req->output.used, data, size);
+        req->output.used += size;
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "%s: output.used=%u output.size=%u size=%u\n", __func__, req->output.used, req->output.size, size);
+    }
+    return 0;
+}
+
+static int v4l2_request_controls(V4L2RequestContext *ctx, int request_fd, unsigned long type, struct v4l2_ext_control *control, int count)
+{
+    struct v4l2_ext_controls controls = {
+        .controls = control,
+        .count = count,
+        .request_fd = request_fd,
+        .which = (request_fd >= 0) ? V4L2_CTRL_WHICH_REQUEST_VAL : 0,
+    };
+
+    if (!control || !count)
+        return 0;
+
+    return ioctl(ctx->video_fd, type, &controls);
+}
+
+static int v4l2_request_set_controls(V4L2RequestContext *ctx, int request_fd, struct v4l2_ext_control *control, int count)
+{
+    return v4l2_request_controls(ctx, request_fd, VIDIOC_S_EXT_CTRLS, control, count);
+}
+
+int ff_v4l2_request_set_controls(AVCodecContext *avctx, struct v4l2_ext_control *control, int count)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+
+    ret = v4l2_request_controls(ctx, -1, VIDIOC_S_EXT_CTRLS, control, count);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: set controls failed, %s (%d)\n", __func__, strerror(errno), errno);
+        return AVERROR(EINVAL);
+    }
+
+    return ret;
+}
+
+int ff_v4l2_request_get_controls(AVCodecContext *avctx, struct v4l2_ext_control *control, int count)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+
+    ret = v4l2_request_controls(ctx, -1, VIDIOC_G_EXT_CTRLS, control, count);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get controls failed, %s (%d)\n", __func__, strerror(errno), errno);
+        return AVERROR(EINVAL);
+    }
+
+    return ret;
+}
+
+int ff_v4l2_request_query_control(AVCodecContext *avctx, struct v4l2_query_ext_ctrl *control)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+
+    ret = ioctl(ctx->video_fd, VIDIOC_QUERY_EXT_CTRL, control);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: query control failed, %s (%d)\n", __func__, strerror(errno), errno);
+        return AVERROR(EINVAL);
+    }
+
+    return 0;
+}
+
+int ff_v4l2_request_query_control_default_value(AVCodecContext *avctx, uint32_t id)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    struct v4l2_queryctrl control = { .id = id };
+    int ret;
+
+    ret = ioctl(ctx->video_fd, VIDIOC_QUERYCTRL, &control);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: query control failed, %s (%d)\n", __func__, strerror(errno), errno);
+        return AVERROR(EINVAL);
+    }
+
+    return control.default_value;
+}
+
+static int v4l2_request_queue_buffer(V4L2RequestContext *ctx, int request_fd, V4L2RequestBuffer *buf, uint32_t flags)
+{
+    struct v4l2_plane planes[1] = {};
+    struct v4l2_buffer buffer = {
+        .type = buf->buffer.type,
+        .memory = buf->buffer.memory,
+        .index = buf->index,
+        .timestamp.tv_usec = ctx->timestamp,
+        .bytesused = buf->used,
+        .request_fd = request_fd,
+        .flags = ((request_fd >= 0) ? V4L2_BUF_FLAG_REQUEST_FD : 0) | flags,
+    };
+
+    buf->buffer.flags = buffer.flags;
+    buf->buffer.timestamp = buffer.timestamp;
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(buf->buffer.type)) {
+        planes[0].bytesused = buf->used;
+        buffer.bytesused = 0;
+        buffer.length = 1;
+        buffer.m.planes = planes;
+    }
+
+    return ioctl(ctx->video_fd, VIDIOC_QBUF, &buffer);
+}
+
+static int v4l2_request_dequeue_buffer(V4L2RequestContext *ctx, V4L2RequestBuffer *buf)
+{
+    int ret;
+    struct v4l2_plane planes[1] = {};
+    struct v4l2_buffer buffer = {
+        .type = buf->buffer.type,
+        .memory = buf->buffer.memory,
+        .index = buf->index,
+    };
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(buf->buffer.type)) {
+        buffer.length = 1;
+        buffer.m.planes = planes;
+    }
+
+    ret = ioctl(ctx->video_fd, VIDIOC_DQBUF, &buffer);
+    if (ret < 0)
+        return ret;
+
+    buf->buffer.flags = buffer.flags;
+    buf->buffer.timestamp = buffer.timestamp;
+    return 0;
+}
+
+const uint32_t v4l2_request_capture_pixelformats[] = {
+    V4L2_PIX_FMT_NV12,
+#ifdef DRM_FORMAT_MOD_ALLWINNER_TILED
+    V4L2_PIX_FMT_SUNXI_TILED_NV12,
+#endif
+};
+
+static int v4l2_request_set_drm_descriptor(V4L2RequestDescriptor *req, struct v4l2_format *format)
+{
+    AVDRMFrameDescriptor *desc = &req->drm;
+    AVDRMLayerDescriptor *layer = &desc->layers[0];
+    uint32_t pixelformat = V4L2_TYPE_IS_MULTIPLANAR(format->type) ? format->fmt.pix_mp.pixelformat : format->fmt.pix.pixelformat;
+
+    switch (pixelformat) {
+    case V4L2_PIX_FMT_NV12:
+        layer->format = DRM_FORMAT_NV12;
+        desc->objects[0].format_modifier = DRM_FORMAT_MOD_LINEAR;
+        break;
+#ifdef DRM_FORMAT_MOD_ALLWINNER_TILED
+    case V4L2_PIX_FMT_SUNXI_TILED_NV12:
+        layer->format = DRM_FORMAT_NV12;
+        desc->objects[0].format_modifier = DRM_FORMAT_MOD_ALLWINNER_TILED;
+        break;
+#endif
+    default:
+        return -1;
+    }
+
+    desc->nb_objects = 1;
+    desc->objects[0].fd = req->capture.fd;
+    desc->objects[0].size = req->capture.size;
+
+    desc->nb_layers = 1;
+    layer->nb_planes = 2;
+
+    layer->planes[0].object_index = 0;
+    layer->planes[0].offset = 0;
+    layer->planes[0].pitch = V4L2_TYPE_IS_MULTIPLANAR(format->type) ? format->fmt.pix_mp.plane_fmt[0].bytesperline : format->fmt.pix.bytesperline;
+
+    layer->planes[1].object_index = 0;
+    layer->planes[1].offset = layer->planes[0].pitch * (V4L2_TYPE_IS_MULTIPLANAR(format->type) ? format->fmt.pix_mp.height : format->fmt.pix.height);
+    layer->planes[1].pitch = layer->planes[0].pitch;
+
+    return 0;
+}
+
+static int v4l2_request_queue_decode(AVCodecContext *avctx, AVFrame *frame, struct v4l2_ext_control *control, int count, int first_slice, int last_slice)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)frame->data[0];
+    struct timeval tv = { 2, 0 };
+    fd_set except_fds;
+    int ret;
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p used=%u controls=%d index=%d fd=%d request_fd=%d first_slice=%d last_slice=%d\n", __func__, avctx, req->output.used, count, req->capture.index, req->capture.fd, req->request_fd, first_slice, last_slice);
+
+    if (first_slice)
+        ctx->timestamp++;
+
+    ret = v4l2_request_set_controls(ctx, req->request_fd, control, count);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: set controls failed for request %d, %s (%d)\n", __func__, req->request_fd, strerror(errno), errno);
+        return -1;
+    }
+
+    memset(req->output.addr + req->output.used, 0, OUTPUT_BUFFER_PADDING_SIZE);
+
+    ret = v4l2_request_queue_buffer(ctx, req->request_fd, &req->output, last_slice ? 0 : V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: queue output buffer %d failed for request %d, %s (%d)\n", __func__, req->output.index, req->request_fd, strerror(errno), errno);
+        return -1;
+    }
+
+    if (first_slice) {
+        ret = v4l2_request_queue_buffer(ctx, -1, &req->capture, 0);
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "%s: queue capture buffer %d failed for request %d, %s (%d)\n", __func__, req->capture.index, req->request_fd, strerror(errno), errno);
+            return -1;
+        }
+    }
+
+    ret = ioctl(req->request_fd, MEDIA_REQUEST_IOC_QUEUE, NULL);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: queue request %d failed, %s (%d)\n", __func__, req->request_fd, strerror(errno), errno);
+        goto fail;
+    }
+
+    FD_ZERO(&except_fds);
+    FD_SET(req->request_fd, &except_fds);
+
+    ret = select(req->request_fd + 1, NULL, NULL, &except_fds, &tv);
+    if (ret == 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: request %d timeout\n", __func__, req->request_fd);
+        goto fail;
+    } else if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: select request %d failed, %s (%d)\n", __func__, req->request_fd, strerror(errno), errno);
+        goto fail;
+    }
+
+    ret = v4l2_request_dequeue_buffer(ctx, &req->output);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: dequeue output buffer %d failed for request %d, %s (%d)\n", __func__, req->output.index, req->request_fd, strerror(errno), errno);
+        return -1;
+    }
+
+    if (last_slice) {
+        ret = v4l2_request_dequeue_buffer(ctx, &req->capture);
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "%s: dequeue capture buffer %d failed for request %d, %s (%d)\n", __func__, req->capture.index, req->request_fd, strerror(errno), errno);
+            return -1;
+        }
+
+        if (req->capture.buffer.flags & V4L2_BUF_FLAG_ERROR) {
+            av_log(avctx, AV_LOG_WARNING, "%s: capture buffer %d flagged with error for request %d\n", __func__, req->capture.index, req->request_fd);
+            frame->flags |= AV_FRAME_FLAG_CORRUPT;
+        }
+    }
+
+    ret = ioctl(req->request_fd, MEDIA_REQUEST_IOC_REINIT, NULL);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: reinit request %d failed, %s (%d)\n", __func__, req->request_fd, strerror(errno), errno);
+        return -1;
+    }
+
+    if (last_slice)
+        return v4l2_request_set_drm_descriptor(req, &ctx->format);
+
+    return 0;
+
+fail:
+    ret = v4l2_request_dequeue_buffer(ctx, &req->output);
+    if (ret < 0)
+        av_log(avctx, AV_LOG_ERROR, "%s: dequeue output buffer %d failed for request %d, %s (%d)\n", __func__, req->output.index, req->request_fd, strerror(errno), errno);
+
+    ret = v4l2_request_dequeue_buffer(ctx, &req->capture);
+    if (ret < 0)
+        av_log(avctx, AV_LOG_ERROR, "%s: dequeue capture buffer %d failed for request %d, %s (%d)\n", __func__, req->capture.index, req->request_fd, strerror(errno), errno);
+
+    ret = ioctl(req->request_fd, MEDIA_REQUEST_IOC_REINIT, NULL);
+    if (ret < 0)
+        av_log(avctx, AV_LOG_ERROR, "%s: reinit request %d failed, %s (%d)\n", __func__, req->request_fd, strerror(errno), errno);
+
+    return -1;
+}
+
+int ff_v4l2_request_decode_slice(AVCodecContext *avctx, AVFrame *frame, struct v4l2_ext_control *control, int count, int first_slice, int last_slice)
+{
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)frame->data[0];
+
+    /* fall back to queue each slice as a full frame */
+    if ((req->output.capabilities & V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF) != V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF)
+        return v4l2_request_queue_decode(avctx, frame, control, count, 1, 1);
+
+    return v4l2_request_queue_decode(avctx, frame, control, count, first_slice, last_slice);
+}
+
+int ff_v4l2_request_decode_frame(AVCodecContext *avctx, AVFrame *frame, struct v4l2_ext_control *control, int count)
+{
+    return v4l2_request_queue_decode(avctx, frame, control, count, 1, 1);
+}
+
+static int v4l2_request_try_format(AVCodecContext *avctx, enum v4l2_buf_type type, uint32_t pixelformat)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    struct v4l2_fmtdesc fmtdesc = {
+        .index = 0,
+        .type = type,
+    };
+
+    if (V4L2_TYPE_IS_OUTPUT(type)) {
+        struct v4l2_create_buffers buffers = {
+            .count = 0,
+            .memory = V4L2_MEMORY_MMAP,
+            .format.type = type,
+        };
+
+        if (ioctl(ctx->video_fd, VIDIOC_CREATE_BUFS, &buffers) < 0) {
+            av_log(avctx, AV_LOG_ERROR, "%s: create buffers failed for type %u, %s (%d)\n", __func__, type, strerror(errno), errno);
+            return -1;
+        }
+
+        if ((buffers.capabilities & V4L2_BUF_CAP_SUPPORTS_REQUESTS) != V4L2_BUF_CAP_SUPPORTS_REQUESTS) {
+            av_log(avctx, AV_LOG_INFO, "%s: output buffer type do not support requests, capabilities %u\n", __func__, buffers.capabilities);
+            return -1;
+        }
+    }
+
+    while (ioctl(ctx->video_fd, VIDIOC_ENUM_FMT, &fmtdesc) >= 0) {
+        if (fmtdesc.pixelformat == pixelformat)
+            return 0;
+
+        fmtdesc.index++;
+    }
+
+    av_log(avctx, AV_LOG_INFO, "%s: pixelformat %u not supported for type %u\n", __func__, pixelformat, type);
+    return -1;
+}
+
+static int v4l2_request_set_format(AVCodecContext *avctx, enum v4l2_buf_type type, uint32_t pixelformat, uint32_t buffersize)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    struct v4l2_format format = {
+        .type = type,
+    };
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(type)) {
+        format.fmt.pix_mp.width = avctx->coded_width;
+        format.fmt.pix_mp.height = avctx->coded_height;
+        format.fmt.pix_mp.pixelformat = pixelformat;
+        format.fmt.pix_mp.plane_fmt[0].sizeimage = buffersize;
+        format.fmt.pix_mp.num_planes = 1;
+    } else {
+        format.fmt.pix.width = avctx->coded_width;
+        format.fmt.pix.height = avctx->coded_height;
+        format.fmt.pix.pixelformat = pixelformat;
+        format.fmt.pix.sizeimage = buffersize;
+    }
+
+    return ioctl(ctx->video_fd, VIDIOC_S_FMT, &format);
+}
+
+static int v4l2_request_select_capture_format(AVCodecContext *avctx)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    enum v4l2_buf_type type = ctx->format.type;
+
+    /* V4L2 documentation for stateless decoders suggests the driver should choose the preferred/optimal format */
+    /* but drivers do not fully implement this, so use v4l2_request_capture_pixelformats. */
+#if 0
+    struct v4l2_format format = {
+        .type = type,
+    };
+    struct v4l2_fmtdesc fmtdesc = {
+        .index = 0,
+        .type = type,
+    };
+    uint32_t pixelformat;
+    int i;
+
+    if (ioctl(ctx->video_fd, VIDIOC_G_FMT, &format) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get capture format failed, %s (%d)\n", __func__, strerror(errno), errno);
+        return -1;
+    }
+
+    pixelformat = V4L2_TYPE_IS_MULTIPLANAR(type) ? format.fmt.pix_mp.pixelformat : format.fmt.pix.pixelformat;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(v4l2_request_capture_pixelformats); i++) {
+        if (pixelformat == v4l2_request_capture_pixelformats[i])
+            return v4l2_request_set_format(avctx, type, pixelformat, 0);
+    }
+
+    while (ioctl(ctx->video_fd, VIDIOC_ENUM_FMT, &fmtdesc) >= 0) {
+        for (i = 0; i < FF_ARRAY_ELEMS(v4l2_request_capture_pixelformats); i++) {
+            if (fmtdesc.pixelformat == v4l2_request_capture_pixelformats[i])
+                return v4l2_request_set_format(avctx, type, fmtdesc.pixelformat, 0);
+        }
+
+        fmtdesc.index++;
+    }
+#else
+    for (int i = 0; i < FF_ARRAY_ELEMS(v4l2_request_capture_pixelformats); i++) {
+        uint32_t pixelformat = v4l2_request_capture_pixelformats[i];
+        if (!v4l2_request_try_format(avctx, type, pixelformat))
+            return v4l2_request_set_format(avctx, type, pixelformat, 0);
+    }
+#endif
+
+    return -1;
+}
+
+static int v4l2_request_probe_video_device(struct udev_device *device, AVCodecContext *avctx, uint32_t pixelformat, uint32_t buffersize, struct v4l2_ext_control *control, int count)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret = AVERROR(EINVAL);
+    struct v4l2_capability capability = {0};
+    unsigned int capabilities = 0;
+
+    const char *path = udev_device_get_devnode(device);
+    if (!path) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get video device devnode failed\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ctx->video_fd = open(path, O_RDWR | O_NONBLOCK, 0);
+    if (ctx->video_fd < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: opening %s failed, %s (%d)\n", __func__, path, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = ioctl(ctx->video_fd, VIDIOC_QUERYCAP, &capability);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get video capability failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    if (capability.capabilities & V4L2_CAP_DEVICE_CAPS)
+        capabilities = capability.device_caps;
+    else
+        capabilities = capability.capabilities;
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p ctx=%p path=%s capabilities=%u\n", __func__, avctx, ctx, path, capabilities);
+
+    if ((capabilities & V4L2_CAP_STREAMING) != V4L2_CAP_STREAMING) {
+        av_log(avctx, AV_LOG_ERROR, "%s: missing required streaming capability\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    if ((capabilities & V4L2_CAP_VIDEO_M2M_MPLANE) == V4L2_CAP_VIDEO_M2M_MPLANE) {
+        ctx->output_type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+        ctx->format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+    } else if ((capabilities & V4L2_CAP_VIDEO_M2M) == V4L2_CAP_VIDEO_M2M) {
+        ctx->output_type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+        ctx->format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "%s: missing required mem2mem capability\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = v4l2_request_try_format(avctx, ctx->output_type, pixelformat);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_WARNING, "%s: try output format failed\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = v4l2_request_set_format(avctx, ctx->output_type, pixelformat, buffersize);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: set output format failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = v4l2_request_set_controls(ctx, -1, control, count);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: set controls failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = v4l2_request_select_capture_format(avctx);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_WARNING, "%s: select capture format failed\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    return 0;
+
+fail:
+    if (ctx->video_fd >= 0) {
+        close(ctx->video_fd);
+        ctx->video_fd = -1;
+    }
+    return ret;
+}
+
+static int v4l2_request_init_context(AVCodecContext *avctx)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+
+    ret = ioctl(ctx->video_fd, VIDIOC_G_FMT, &ctx->format);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get capture format failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(ctx->format.type)) {
+        av_log(avctx, AV_LOG_DEBUG, "%s: pixelformat=%d width=%u height=%u bytesperline=%u sizeimage=%u num_planes=%u\n", __func__, ctx->format.fmt.pix_mp.pixelformat, ctx->format.fmt.pix_mp.width, ctx->format.fmt.pix_mp.height, ctx->format.fmt.pix_mp.plane_fmt[0].bytesperline, ctx->format.fmt.pix_mp.plane_fmt[0].sizeimage, ctx->format.fmt.pix_mp.num_planes);
+    } else {
+        av_log(avctx, AV_LOG_DEBUG, "%s: pixelformat=%d width=%u height=%u bytesperline=%u sizeimage=%u\n", __func__, ctx->format.fmt.pix.pixelformat, ctx->format.fmt.pix.width, ctx->format.fmt.pix.height, ctx->format.fmt.pix.bytesperline, ctx->format.fmt.pix.sizeimage);
+    }
+
+    ret = ff_decode_get_hw_frames_ctx(avctx, AV_HWDEVICE_TYPE_DRM);
+    if (ret < 0)
+        goto fail;
+
+    ret = ioctl(ctx->video_fd, VIDIOC_STREAMON, &ctx->output_type);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: output stream on failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = ioctl(ctx->video_fd, VIDIOC_STREAMON, &ctx->format.type);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: capture stream on failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    return 0;
+
+fail:
+    ff_v4l2_request_uninit(avctx);
+    return ret;
+}
+
+static int v4l2_request_probe_media_device(struct udev_device *device, AVCodecContext *avctx, uint32_t pixelformat, uint32_t buffersize, struct v4l2_ext_control *control, int count)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+    struct media_device_info device_info = {0};
+    struct media_v2_topology topology = {0};
+    struct media_v2_interface *interfaces = NULL;
+    struct udev *udev = udev_device_get_udev(device);
+    struct udev_device *video_device;
+    dev_t devnum;
+
+    const char *path = udev_device_get_devnode(device);
+    if (!path) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get media device devnode failed\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ctx->media_fd = open(path, O_RDWR, 0);
+    if (ctx->media_fd < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: opening %s failed, %s (%d)\n", __func__, path, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = ioctl(ctx->media_fd, MEDIA_IOC_DEVICE_INFO, &device_info);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get media device info failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p ctx=%p path=%s driver=%s\n", __func__, avctx, ctx, path, device_info.driver);
+
+    ret = ioctl(ctx->media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get media topology failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    if (topology.num_interfaces <= 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: media device has no interfaces\n", __func__);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    interfaces = av_mallocz(topology.num_interfaces * sizeof(struct media_v2_interface));
+    if (!interfaces) {
+        av_log(avctx, AV_LOG_ERROR, "%s: allocating media interface struct failed\n", __func__);
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    topology.ptr_interfaces = (__u64)(uintptr_t)interfaces;
+    ret = ioctl(ctx->media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get media topology failed, %s (%d)\n", __func__, strerror(errno), errno);
+        ret = AVERROR(EINVAL);
+        goto fail;
+    }
+
+    ret = AVERROR(EINVAL);
+    for (int i = 0; i < topology.num_interfaces; i++) {
+        if (interfaces[i].intf_type != MEDIA_INTF_T_V4L_VIDEO)
+            continue;
+
+        devnum = makedev(interfaces[i].devnode.major, interfaces[i].devnode.minor);
+        video_device = udev_device_new_from_devnum(udev, 'c', devnum);
+        if (!video_device) {
+            av_log(avctx, AV_LOG_ERROR, "%s: video_device=%p\n", __func__, video_device);
+            continue;
+        }
+
+        ret = v4l2_request_probe_video_device(video_device, avctx, pixelformat, buffersize, control, count);
+        udev_device_unref(video_device);
+
+        if (!ret)
+            break;
+    }
+
+    av_freep(&interfaces);
+    return ret;
+
+fail:
+    av_freep(&interfaces);
+    if (ctx->media_fd >= 0) {
+        close(ctx->media_fd);
+        ctx->media_fd = -1;
+    }
+    return ret;
+}
+
+int ff_v4l2_request_init(AVCodecContext *avctx, uint32_t pixelformat, uint32_t buffersize, struct v4l2_ext_control *control, int count)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret = AVERROR(EINVAL);
+    struct udev *udev;
+    struct udev_enumerate *enumerate;
+    struct udev_list_entry *devices;
+    struct udev_list_entry *entry;
+    struct udev_device *device;
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p hw_device_ctx=%p hw_frames_ctx=%p\n", __func__, avctx, avctx->hw_device_ctx, avctx->hw_frames_ctx);
+
+    ctx->media_fd = -1;
+    ctx->video_fd = -1;
+    ctx->timestamp = 0;
+
+    udev = udev_new();
+    if (!udev) {
+        av_log(avctx, AV_LOG_ERROR, "%s: allocating udev context failed\n", __func__);
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    enumerate = udev_enumerate_new(udev);
+    if (!enumerate) {
+        av_log(avctx, AV_LOG_ERROR, "%s: allocating udev enumerator failed\n", __func__);
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    udev_enumerate_add_match_subsystem(enumerate, "media");
+    udev_enumerate_scan_devices(enumerate);
+
+    devices = udev_enumerate_get_list_entry(enumerate);
+    udev_list_entry_foreach(entry, devices) {
+        const char *path = udev_list_entry_get_name(entry);
+        if (!path)
+            continue;
+
+        device = udev_device_new_from_syspath(udev, path);
+        if (!device)
+            continue;
+
+        ret = v4l2_request_probe_media_device(device, avctx, pixelformat, buffersize, control, count);
+        udev_device_unref(device);
+
+        if (!ret)
+            break;
+    }
+
+    udev_enumerate_unref(enumerate);
+
+    if (!ret)
+        ret = v4l2_request_init_context(avctx);
+
+fail:
+    udev_unref(udev);
+    return ret;
+}
+
+int ff_v4l2_request_uninit(AVCodecContext *avctx)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p ctx=%p\n", __func__, avctx, ctx);
+
+    if (ctx->video_fd >= 0) {
+        ret = ioctl(ctx->video_fd, VIDIOC_STREAMOFF, &ctx->output_type);
+        if (ret < 0)
+            av_log(avctx, AV_LOG_ERROR, "%s: output stream off failed, %s (%d)\n", __func__, strerror(errno), errno);
+
+        ret = ioctl(ctx->video_fd, VIDIOC_STREAMOFF, &ctx->format.type);
+        if (ret < 0)
+            av_log(avctx, AV_LOG_ERROR, "%s: capture stream off failed, %s (%d)\n", __func__, strerror(errno), errno);
+    }
+
+    if (avctx->hw_frames_ctx) {
+        AVHWFramesContext *hwfc = (AVHWFramesContext*)avctx->hw_frames_ctx->data;
+        av_buffer_pool_flush(hwfc->pool);
+    }
+
+    if (ctx->video_fd >= 0)
+        close(ctx->video_fd);
+
+    if (ctx->media_fd >= 0)
+        close(ctx->media_fd);
+
+    return 0;
+}
+
+static int v4l2_request_buffer_alloc(AVCodecContext *avctx, V4L2RequestBuffer *buf, enum v4l2_buf_type type)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    int ret;
+    struct v4l2_plane planes[1] = {};
+    struct v4l2_create_buffers buffers = {
+        .count = 1,
+        .memory = V4L2_MEMORY_MMAP,
+        .format.type = type,
+    };
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p buf=%p type=%u\n", __func__, avctx, buf, type);
+
+    ret = ioctl(ctx->video_fd, VIDIOC_G_FMT, &buffers.format);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: get format failed for type %u, %s (%d)\n", __func__, type, strerror(errno), errno);
+        return ret;
+    }
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(buffers.format.type)) {
+        av_log(avctx, AV_LOG_DEBUG, "%s: pixelformat=%d width=%u height=%u bytesperline=%u sizeimage=%u num_planes=%u\n", __func__, buffers.format.fmt.pix_mp.pixelformat, buffers.format.fmt.pix_mp.width, buffers.format.fmt.pix_mp.height, buffers.format.fmt.pix_mp.plane_fmt[0].bytesperline, buffers.format.fmt.pix_mp.plane_fmt[0].sizeimage, buffers.format.fmt.pix_mp.num_planes);
+    } else {
+        av_log(avctx, AV_LOG_DEBUG, "%s: pixelformat=%d width=%u height=%u bytesperline=%u sizeimage=%u\n", __func__, buffers.format.fmt.pix.pixelformat, buffers.format.fmt.pix.width, buffers.format.fmt.pix.height, buffers.format.fmt.pix.bytesperline, buffers.format.fmt.pix.sizeimage);
+    }
+
+    ret = ioctl(ctx->video_fd, VIDIOC_CREATE_BUFS, &buffers);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: create buffers failed for type %u, %s (%d)\n", __func__, type, strerror(errno), errno);
+        return ret;
+    }
+
+    if (V4L2_TYPE_IS_MULTIPLANAR(type)) {
+        buf->width = buffers.format.fmt.pix_mp.width;
+        buf->height = buffers.format.fmt.pix_mp.height;
+        buf->size = buffers.format.fmt.pix_mp.plane_fmt[0].sizeimage;
+        buf->buffer.length = 1;
+        buf->buffer.m.planes = planes;
+    } else {
+        buf->width = buffers.format.fmt.pix.width;
+        buf->height = buffers.format.fmt.pix.height;
+        buf->size = buffers.format.fmt.pix.sizeimage;
+    }
+
+    buf->index = buffers.index;
+    buf->capabilities = buffers.capabilities;
+    buf->used = 0;
+
+    buf->buffer.type = type;
+    buf->buffer.memory = V4L2_MEMORY_MMAP;
+    buf->buffer.index = buf->index;
+
+    ret = ioctl(ctx->video_fd, VIDIOC_QUERYBUF, &buf->buffer);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: query buffer %d failed, %s (%d)\n", __func__, buf->index, strerror(errno), errno);
+        return ret;
+    }
+
+    if (V4L2_TYPE_IS_OUTPUT(type)) {
+        void *addr = mmap(NULL, buf->size, PROT_READ | PROT_WRITE, MAP_SHARED, ctx->video_fd, V4L2_TYPE_IS_MULTIPLANAR(type) ? buf->buffer.m.planes[0].m.mem_offset : buf->buffer.m.offset);
+        if (addr == MAP_FAILED) {
+            av_log(avctx, AV_LOG_ERROR, "%s: mmap failed, %s (%d)\n", __func__, strerror(errno), errno);
+            return -1;
+        }
+
+        buf->addr = (uint8_t*)addr;
+    } else {
+        struct v4l2_exportbuffer exportbuffer = {
+            .type = type,
+            .index = buf->index,
+            .flags = O_RDONLY,
+        };
+
+        ret = ioctl(ctx->video_fd, VIDIOC_EXPBUF, &exportbuffer);
+        if (ret < 0) {
+            av_log(avctx, AV_LOG_ERROR, "%s: export buffer %d failed, %s (%d)\n", __func__, buf->index, strerror(errno), errno);
+            return ret;
+        }
+
+        buf->fd = exportbuffer.fd;
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: buf=%p index=%d fd=%d addr=%p width=%u height=%u size=%u\n", __func__, buf, buf->index, buf->fd, buf->addr, buf->width, buf->height, buf->size);
+    return 0;
+}
+
+static void v4l2_request_buffer_free(V4L2RequestBuffer *buf)
+{
+    av_log(NULL, AV_LOG_DEBUG, "%s: buf=%p index=%d fd=%d addr=%p width=%u height=%u size=%u\n", __func__, buf, buf->index, buf->fd, buf->addr, buf->width, buf->height, buf->size);
+
+    if (buf->addr)
+        munmap(buf->addr, buf->size);
+
+    if (buf->fd >= 0)
+        close(buf->fd);
+}
+
+static void v4l2_request_frame_free(void *opaque, uint8_t *data)
+{
+    AVCodecContext *avctx = opaque;
+    V4L2RequestDescriptor *req = (V4L2RequestDescriptor*)data;
+
+    av_log(NULL, AV_LOG_DEBUG, "%s: avctx=%p data=%p request_fd=%d\n", __func__, avctx, data, req->request_fd);
+
+    if (req->request_fd >= 0)
+        close(req->request_fd);
+
+    v4l2_request_buffer_free(&req->capture);
+    v4l2_request_buffer_free(&req->output);
+
+    av_free(data);
+}
+
+static AVBufferRef *v4l2_request_frame_alloc(void *opaque, int size)
+{
+    AVCodecContext *avctx = opaque;
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    V4L2RequestDescriptor *req;
+    AVBufferRef *ref;
+    uint8_t *data;
+    int ret;
+
+    data = av_mallocz(size);
+    if (!data)
+        return NULL;
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p size=%d data=%p\n", __func__, avctx, size, data);
+
+    ref = av_buffer_create(data, size, v4l2_request_frame_free, avctx, 0);
+    if (!ref) {
+        av_freep(&data);
+        return NULL;
+    }
+
+    req = (V4L2RequestDescriptor*)data;
+    req->request_fd = -1;
+    req->output.fd = -1;
+    req->capture.fd = -1;
+
+    ret = v4l2_request_buffer_alloc(avctx, &req->output, ctx->output_type);
+    if (ret < 0) {
+        av_buffer_unref(&ref);
+        return NULL;
+    }
+
+    ret = v4l2_request_buffer_alloc(avctx, &req->capture, ctx->format.type);
+    if (ret < 0) {
+        av_buffer_unref(&ref);
+        return NULL;
+    }
+
+    ret = ioctl(ctx->media_fd, MEDIA_IOC_REQUEST_ALLOC, &req->request_fd);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "%s: request alloc failed, %s (%d)\n", __func__, strerror(errno), errno);
+        av_buffer_unref(&ref);
+        return NULL;
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p size=%d data=%p request_fd=%d\n", __func__, avctx, size, data, req->request_fd);
+    return ref;
+}
+
+static void v4l2_request_pool_free(void *opaque)
+{
+    av_log(NULL, AV_LOG_DEBUG, "%s: opaque=%p\n", __func__, opaque);
+}
+
+static void v4l2_request_hwframe_ctx_free(AVHWFramesContext *hwfc)
+{
+    av_log(NULL, AV_LOG_DEBUG, "%s: hwfc=%p pool=%p\n", __func__, hwfc, hwfc->pool);
+
+    av_buffer_pool_flush(hwfc->pool);
+    av_buffer_pool_uninit(&hwfc->pool);
+}
+
+int ff_v4l2_request_frame_params(AVCodecContext *avctx, AVBufferRef *hw_frames_ctx)
+{
+    V4L2RequestContext *ctx = avctx->internal->hwaccel_priv_data;
+    AVHWFramesContext *hwfc = (AVHWFramesContext*)hw_frames_ctx->data;
+
+    hwfc->format = AV_PIX_FMT_DRM_PRIME;
+    hwfc->sw_format = AV_PIX_FMT_NV12;
+    if (V4L2_TYPE_IS_MULTIPLANAR(ctx->format.type)) {
+        hwfc->width = ctx->format.fmt.pix_mp.width;
+        hwfc->height = ctx->format.fmt.pix_mp.height;
+    } else {
+        hwfc->width = ctx->format.fmt.pix.width;
+        hwfc->height = ctx->format.fmt.pix.height;
+    }
+
+    hwfc->pool = av_buffer_pool_init2(sizeof(V4L2RequestDescriptor), avctx, v4l2_request_frame_alloc, v4l2_request_pool_free);
+    if (!hwfc->pool)
+        return AVERROR(ENOMEM);
+
+    hwfc->free = v4l2_request_hwframe_ctx_free;
+
+    hwfc->initial_pool_size = 1;
+
+    switch (avctx->codec_id) {
+    case AV_CODEC_ID_VP9:
+        hwfc->initial_pool_size += 8;
+        break;
+    case AV_CODEC_ID_VP8:
+        hwfc->initial_pool_size += 3;
+        break;
+    default:
+        hwfc->initial_pool_size += 2;
+    }
+
+    av_log(avctx, AV_LOG_DEBUG, "%s: avctx=%p ctx=%p hw_frames_ctx=%p hwfc=%p pool=%p width=%d height=%d initial_pool_size=%d\n", __func__, avctx, ctx, hw_frames_ctx, hwfc, hwfc->pool, hwfc->width, hwfc->height, hwfc->initial_pool_size);
+
+    return 0;
+}
diff --git a/libavcodec/v4l2_request.h b/libavcodec/v4l2_request.h
new file mode 100644
index 0000000000..58d2aa70af
--- /dev/null
+++ b/libavcodec/v4l2_request.h
@@ -0,0 +1,77 @@ 
+/*
+ * 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
+ */
+
+#ifndef AVCODEC_V4L2_REQUEST_H
+#define AVCODEC_V4L2_REQUEST_H
+
+#include <linux/videodev2.h>
+
+#include "libavutil/hwcontext_drm.h"
+
+typedef struct V4L2RequestContext {
+    int video_fd;
+    int media_fd;
+    enum v4l2_buf_type output_type;
+    struct v4l2_format format;
+    int timestamp;
+} V4L2RequestContext;
+
+typedef struct V4L2RequestBuffer {
+    int index;
+    int fd;
+    uint8_t *addr;
+    uint32_t width;
+    uint32_t height;
+    uint32_t size;
+    uint32_t used;
+    uint32_t capabilities;
+    struct v4l2_buffer buffer;
+} V4L2RequestBuffer;
+
+typedef struct V4L2RequestDescriptor {
+    AVDRMFrameDescriptor drm;
+    int request_fd;
+    V4L2RequestBuffer output;
+    V4L2RequestBuffer capture;
+} V4L2RequestDescriptor;
+
+uint64_t ff_v4l2_request_get_capture_timestamp(AVFrame *frame);
+
+int ff_v4l2_request_reset_frame(AVCodecContext *avctx, AVFrame *frame);
+
+int ff_v4l2_request_append_output_buffer(AVCodecContext *avctx, AVFrame *frame, const uint8_t *data, uint32_t size);
+
+int ff_v4l2_request_set_controls(AVCodecContext *avctx, struct v4l2_ext_control *control, int count);
+
+int ff_v4l2_request_get_controls(AVCodecContext *avctx, struct v4l2_ext_control *control, int count);
+
+int ff_v4l2_request_query_control(AVCodecContext *avctx, struct v4l2_query_ext_ctrl *control);
+
+int ff_v4l2_request_query_control_default_value(AVCodecContext *avctx, uint32_t id);
+
+int ff_v4l2_request_decode_slice(AVCodecContext *avctx, AVFrame *frame, struct v4l2_ext_control *control, int count, int first_slice, int last_slice);
+
+int ff_v4l2_request_decode_frame(AVCodecContext *avctx, AVFrame *frame, struct v4l2_ext_control *control, int count);
+
+int ff_v4l2_request_init(AVCodecContext *avctx, uint32_t pixelformat, uint32_t buffersize, struct v4l2_ext_control *control, int count);
+
+int ff_v4l2_request_uninit(AVCodecContext *avctx);
+
+int ff_v4l2_request_frame_params(AVCodecContext *avctx, AVBufferRef *hw_frames_ctx);
+
+#endif /* AVCODEC_V4L2_REQUEST_H */