Mac AVFoundation: Allow use of all camera's supported resolutions.

media/video/capture/mac/video_capture_device_avfoundation_mac.mm

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "media/video/capture/mac/video_capture_device_avfoundation_mac.h"
 
 #import <CoreVideo/CoreVideo.h>
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
@@ skipping 157 matching lines @@
   // VideoCaptureDeviceMac::ReceiveFrame() is calling here, depending on the
   // running state. VCDM::ReceiveFrame() calls here to change aspect ratio.
   DCHECK((![captureSession_ isRunning] &&
       main_thread_checker_.CalledOnValidThread()) ||
       callback_thread_checker_.CalledOnValidThread());
 
   frameWidth_ = width;
   frameHeight_ = height;
   frameRate_ = frameRate;
 
   // Identify the sessionPreset that corresponds to the desired resolution.

[bemasc, 2014/04/28 17:17:33]

This comment should probably be updated, since the preset no longer corresponds
to the desired resolution.  The user could have requested some other resolution
(e.g. 1920x1080).

Moreover ... why is this logic needed at all?  According to the API
documentation, setting the frame size or framerate explicitly automatically
overrides the preset:

"When you change the device’s format, the session preset automatically changes
to this value [AVCaptureSessionPresetInputPriority], indicating that the
AVCaptureSession object has relinquished responsibility for configuring its
inputs and outputs."

Why can't you just delete all mention of presets, if you intend to set the
capture mode explicitly?

[mcasas, 2014/04/28 19:01:36]

Seems that you're right, despite the line you copy referring to
the AVCaptureDevice configured preset, which is coming from
a limited number of presets, again, unless going the 
-activeFormat way, which is not in the code now. Let me 
explain:

The way we configure the device is via sessionPreset +
CrAVCaptureVideoDataOutput, this last one using some
configuration keys in the dictionary that are supposedly
not supported but in practice necessary (hence the long 
comment).  See [1]:  "The only key currently supported is 
the kCVPixelBufferPixelFormatTypeKey key."

But, it seems that for some reason, removing the preset
logic allows the CrAVCaptureVideoDataOutput to
pass the configuration to Session and Device, so all
in all, your comment is taken in, and I removed all the
preset logic after dutifully testing with my cameras :)

[1]
https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/...


On 2014/04/28 17:17:33, bemasc wrote:

   NSString* sessionPreset;
-  if (width == 1280 && height == 720 && [captureSession_ canSetSessionPreset:
+  if (width >= 1280 && height >= 720 && [captureSession_ canSetSessionPreset:
           AVFoundationGlue::AVCaptureSessionPreset1280x720()]) {
     sessionPreset = AVFoundationGlue::AVCaptureSessionPreset1280x720();
-  } else if (width == 640 && height == 480 && [captureSession_
-          canSetSessionPreset:
-              AVFoundationGlue::AVCaptureSessionPreset640x480()]) {
+  } else if (width >= 640 && height >= 480 && [captureSession_
+      canSetSessionPreset:AVFoundationGlue::AVCaptureSessionPreset640x480()]) {
     sessionPreset = AVFoundationGlue::AVCaptureSessionPreset640x480();
-  } else if (width == 320 && height == 240 && [captureSession_
-          canSetSessionPreset:
-              AVFoundationGlue::AVCaptureSessionPreset320x240()]) {
+  } else if ([captureSession_
+      canSetSessionPreset:AVFoundationGlue::AVCaptureSessionPreset320x240()]) {

[bemasc, 2014/04/28 17:17:33]

Does such a preset even exist?  It isn't documented at

https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/...

[mcasas, 2014/04/28 19:01:36]

Not in iOS but in Mac:

https://developer.apple.com/library/mac/documentation/AVFoundation/Reference/...

On 2014/04/28 17:17:33, bemasc wrote:

     sessionPreset = AVFoundationGlue::AVCaptureSessionPreset320x240();
   } else {
-    DLOG(ERROR) << "Unsupported resolution (" << width << "x" << height << ")";
+    DLOG(ERROR) << "Preset not found for requested frame size";
     return NO;
   }
   [captureSession_ setSessionPreset:sessionPreset];
 
   // Check that our capture Device can be used with the current preset.
   if (![captureDevice_ supportsAVCaptureSessionPreset:
           [captureSession_ sessionPreset]]){
     DLOG(ERROR) << "Video capture device does not support current preset";
     return NO;
   }
@@ skipping 98 matching lines @@
       [NSString stringWithFormat:@"%@: %@",
                                  [error localizedDescription],
                                  [error localizedFailureReason]];
 
   base::AutoLock lock(lock_);
   if (frameReceiver_)
     frameReceiver_->ReceiveError([str_error UTF8String]);
 }
 
 @end