commit 32b64e895c0231fe6891a8f6335d66f1dad4f1f5
author Andreas Pehrson <apehrson@mozilla.com> Fri Jan 27 15:09:27 2023
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed May 03 09:39:34 2023
tree 46e7922615743c8c43e17504380ee0f977956c8f
parent d3eddff30ca7442f16617f392af6a000c26797e2

Improve ergonomics of dealing with pixel formats in v4l2 camera backend

Bug: webrtc:14830
Change-Id: Ib49bf65895fe008e75223abb03867d412c1b5a60
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/291531
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39976}

modules/video_capture/linux/device_info_v4l2.cc

diff --git a/modules/video_capture/linux/device_info_v4l2.cc b/modules/video_capture/linux/device_info_v4l2.cc
index 5af5801..0a0f55b 100644
--- a/modules/video_capture/linux/device_info_v4l2.cc
+++ b/modules/video_capture/linux/device_info_v4l2.cc
@@ -228,10 +228,10 @@
   video_fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
   video_fmt.fmt.pix.sizeimage = 0;
 
-  int totalFmts = 5;
   unsigned int videoFormats[] = {V4L2_PIX_FMT_MJPEG, V4L2_PIX_FMT_YUV420,
                                  V4L2_PIX_FMT_YUYV, V4L2_PIX_FMT_UYVY,
                                  V4L2_PIX_FMT_NV12};
+  constexpr int totalFmts = sizeof(videoFormats) / sizeof(unsigned int);
 
   int sizes = 13;
   unsigned int size[][2] = {{128, 96},   {160, 120},  {176, 144},  {320, 240},
@@ -261,6 +261,8 @@
             cap.videoType = VideoType::kUYVY;
           } else if (videoFormats[fmts] == V4L2_PIX_FMT_NV12) {
             cap.videoType = VideoType::kNV12;
+          } else {
+            RTC_DCHECK_NOTREACHED();
           }
 
           // get fps of current camera mode

modules/video_capture/linux/video_capture_v4l2.cc

diff --git a/modules/video_capture/linux/video_capture_v4l2.cc b/modules/video_capture/linux/video_capture_v4l2.cc
index 5101a67..a1f8f9b 100644
--- a/modules/video_capture/linux/video_capture_v4l2.cc
+++ b/modules/video_capture/linux/video_capture_v4l2.cc
@@ -115,23 +115,18 @@
   // Supported video formats in preferred order.
   // If the requested resolution is larger than VGA, we prefer MJPEG. Go for
   // I420 otherwise.
-  const int nFormats = 6;
-  unsigned int fmts[nFormats];
-  if (capability.width > 640 || capability.height > 480) {
-    fmts[0] = V4L2_PIX_FMT_MJPEG;
-    fmts[1] = V4L2_PIX_FMT_YUV420;
-    fmts[2] = V4L2_PIX_FMT_YUYV;
-    fmts[3] = V4L2_PIX_FMT_UYVY;
-    fmts[4] = V4L2_PIX_FMT_NV12;
-    fmts[5] = V4L2_PIX_FMT_JPEG;
-  } else {
-    fmts[0] = V4L2_PIX_FMT_YUV420;
-    fmts[1] = V4L2_PIX_FMT_YUYV;
-    fmts[2] = V4L2_PIX_FMT_UYVY;
-    fmts[3] = V4L2_PIX_FMT_NV12;
-    fmts[4] = V4L2_PIX_FMT_MJPEG;
-    fmts[5] = V4L2_PIX_FMT_JPEG;
-  }
+  unsigned int hdFmts[] = {
+      V4L2_PIX_FMT_MJPEG,  V4L2_PIX_FMT_YUV420, V4L2_PIX_FMT_YUYV,
+      V4L2_PIX_FMT_UYVY,   V4L2_PIX_FMT_NV12,   V4L2_PIX_FMT_JPEG,
+  };
+  unsigned int sdFmts[] = {
+      V4L2_PIX_FMT_YUV420, V4L2_PIX_FMT_YUYV,   V4L2_PIX_FMT_UYVY,
+      V4L2_PIX_FMT_NV12,   V4L2_PIX_FMT_MJPEG,  V4L2_PIX_FMT_JPEG,
+  };
+  const bool isHd = capability.width > 640 || capability.height > 480;
+  unsigned int* fmts = isHd ? hdFmts : sdFmts;
+  static_assert(sizeof(hdFmts) == sizeof(sdFmts));
+  constexpr int nFormats = sizeof(hdFmts) / sizeof(unsigned int);
 
   // Enumerate image formats.
   struct v4l2_fmtdesc fmt;
@@ -180,6 +175,8 @@
   else if (video_fmt.fmt.pix.pixelformat == V4L2_PIX_FMT_MJPEG ||
            video_fmt.fmt.pix.pixelformat == V4L2_PIX_FMT_JPEG)
     _captureVideoType = VideoType::kMJPEG;
+  else
+    RTC_DCHECK_NOTREACHED();
 
   // set format and frame size now
   if (ioctl(_deviceFd, VIDIOC_S_FMT, &video_fmt) < 0) {