Heed the Exif white point when playing back (MJPEG) video.

[nageru] / nageru / mixer.cpp

diff --git a/nageru/mixer.cpp b/nageru/mixer.cpp
index 1457aa92316e56400563feeea8a0185b5c76fb4e..9a86682daa91ca19b2325e3858093f55e80a0a27 100644 (file)
--- a/nageru/mixer.cpp
+++ b/nageru/mixer.cpp
@@ -348,6 +348,11 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        ycbcr_format.cb_y_position = 0.5f;
        ycbcr_format.cr_y_position = 0.5f;
 
+       // Initialize the neutral colors to sane values.
+       for (unsigned i = 0; i < MAX_VIDEO_CARDS; ++i) {
+               last_received_neutral_color[i] = RGBTriplet(1.0f, 1.0f, 1.0f);
+       }
+
        // Display chain; shows the live output produced by the main chain (or rather, a copy of it).
        display_chain.reset(new EffectChain(global_flags.width, global_flags.height, resource_pool.get()));
        check_error();
@@ -1004,6 +1009,10 @@ void Mixer::bm_frame(unsigned card_index, uint16_t timecode,
                        new_frame.video_format = video_format;
                        new_frame.y_offset = y_offset;
                        new_frame.cbcr_offset = cbcr_offset;
+                       if (card->type == CardType::FFMPEG_INPUT) {
+                               FFmpegCapture *ffmpeg_capture = static_cast<FFmpegCapture *>(card->capture.get());
+                               new_frame.neutral_color = ffmpeg_capture->get_last_neutral_color();
+                       }
                        card->new_frames.push_back(move(new_frame));
                        card->jitter_history.frame_arrived(video_frame.received_timestamp, frame_length, dropped_frames);
                        card->may_have_dropped_last_frame = false;
@@ -1115,13 +1124,27 @@ void Mixer::thread_func()
                                new_frame->upload_func = nullptr;
                        }
 
+                       // Only set the white balance if it actually changed. This means that the user
+                       // is free to override the white balance in a video with no white balance information
+                       // actually set (ie. r=g=b=1 all the time), or one where the white point is wrong,
+                       // but frame-to-frame decisions will be heeded. We do this pretty much as late
+                       // as possible (ie., after picking out the frame from the buffer), so that we are sure
+                       // that the change takes effect on exactly the right frame.
+                       if (fabs(new_frame->neutral_color.r - last_received_neutral_color[card_index].r) > 1e-3 ||
+                           fabs(new_frame->neutral_color.g - last_received_neutral_color[card_index].g) > 1e-3 ||
+                           fabs(new_frame->neutral_color.b - last_received_neutral_color[card_index].b) > 1e-3) {
+                               theme->set_wb_for_signal(card_index, new_frame->neutral_color.r, new_frame->neutral_color.g, new_frame->neutral_color.b);
+                               last_received_neutral_color[card_index] = new_frame->neutral_color;
+                       }
+
                        if (new_frame->frame->data_copy != nullptr) {
                                int mjpeg_card_index = mjpeg_encoder->get_mjpeg_stream_for_card(card_index);
                                if (mjpeg_card_index != -1) {
-                                       RGBTriplet white_balance = theme->get_white_balance_for_signal(card_index);
-                                       mjpeg_encoder->upload_frame(pts_int, mjpeg_card_index, new_frame->frame, new_frame->video_format, new_frame->y_offset, new_frame->cbcr_offset, move(raw_audio[card_index]), white_balance);
+                                       RGBTriplet neutral_color = theme->get_white_balance_for_signal(card_index);
+                                       mjpeg_encoder->upload_frame(pts_int, mjpeg_card_index, new_frame->frame, new_frame->video_format, new_frame->y_offset, new_frame->cbcr_offset, move(raw_audio[card_index]), neutral_color);
                                }
                        }
+
                }
 
                int64_t frame_duration = output_frame_info.frame_duration;