Swap red and blue when decoding 0.4 mjpeg streams

There was an error in how this was encoded in 0.4, which we need
to handle. There is still some issues with the old streams as
the luminocity handling in 0.4 was not correct.

client/display_channel.cpp

@@ -290,7 +290,7 @@ VideoStream::VideoStream(RedClient& client, Canvas& canvas, DisplayChannel& chan
         _pixmap.width = src_width;
         _pixmap.height = src_height;
 
-	_mjpeg_decoder = new MJpegDecoder(stream_width, stream_height, _stride, _uncompressed_data);
+	_mjpeg_decoder = new MJpegDecoder(stream_width, stream_height, _stride, _uncompressed_data, channel.get_peer_major() == 1);
 
 #ifdef WIN32
         SetViewportOrgEx(_dc, 0, stream_height - src_height, NULL);

client/mjpeg_decoder.cpp

@@ -65,7 +65,8 @@ extern "C" {
 
 MJpegDecoder::MJpegDecoder(int width, int height,
                            int stride,
-                           uint8_t *frame) :
+                           uint8_t *frame,
+                           bool back_compat) :
     _data(NULL)
     , _data_size(0)
     , _data_start(0)
@@ -75,6 +76,7 @@ MJpegDecoder::MJpegDecoder(int width, int height,
     , _height(height)
     , _stride(stride)
     , _frame(frame)
+    , _back_compat(back_compat)
     , _y(0)
     , _state(0)
 {
@@ -114,16 +116,23 @@ void MJpegDecoder::convert_scanline(void)
    row = (uint32_t *)(_frame + _y * _stride);
     s = _scanline;
 
-    /* TODO after major bump.
-       We need to check for the old major and for backwards compat
-       a) swap r and b
-       b) to-yuv with right values and then from-yuv with old wrong values
-    */
 
-    for (x = 0; x < _width; x++) {
-        c = s[0] << 16 | s[1] << 8 | s[2];
-        s += 3;
-        *row++ = c;
+    if (_back_compat) {
+        /* We need to check for the old major and for backwards compat
+           a) swap r and b (done)
+           b) to-yuv with right values and then from-yuv with old wrong values (TODO)
+        */
+        for (x = 0; x < _width; x++) {
+            c = s[2] << 16 | s[1] << 8 | s[0];
+            s += 3;
+            *row++ = c;
+        }
+    } else {
+        for (x = 0; x < _width; x++) {
+            c = s[0] << 16 | s[1] << 8 | s[2];
+            s += 3;
+            *row++ = c;
+        }
     }
 }
 

client/mjpeg_decoder.h

@@ -37,7 +37,7 @@ extern "C" {
 class MJpegDecoder {
 public:
     MJpegDecoder(int width, int height, int stride,
-                 uint8_t *frame);
+                 uint8_t *frame, bool back_compat);
     ~MJpegDecoder();
 
     bool decode_data(uint8_t *data, size_t length);
@@ -63,6 +63,7 @@ private:
     int _height;
     int _stride;
     uint8_t *_frame;
+    bool _back_compat;
 
     int _y;
     uint8_t *_scanline;