Return second field offset for interlaced modes (1080i only for now).

diff --git a/bmusb.cpp b/bmusb.cpp
index 11decd9b430b78729cf723dd1976c643a1cb0c9f..eca07a8d2d9f000a66bd6639fb6dee44c74c6d8c 100644 (file)
--- a/bmusb.cpp
+++ b/bmusb.cpp
@@ -256,9 +256,9 @@ void BMUSBCapture::start_new_frame(const uint8_t *start)
 
                // Update the assumed frame width. We might be one frame too late on format changes,
                // but it's much better than asking the user to choose manually.
-               unsigned width, height, extra_lines_top, extra_lines_bottom, frame_rate_nom, frame_rate_den;
+               unsigned width, height, second_field_start, extra_lines_top, extra_lines_bottom, frame_rate_nom, frame_rate_den;
                bool interlaced;
-               if (decode_video_format(format, &width, &height, &extra_lines_top, &extra_lines_bottom,
+               if (decode_video_format(format, &width, &height, &second_field_start, &extra_lines_top, &extra_lines_bottom,
                                        &frame_rate_nom, &frame_rate_den, &interlaced)) {
                        assumed_frame_width = width;
                }
@@ -1113,19 +1113,20 @@ void BMUSBCapture::stop_bm_thread()
 
 struct VideoFormatEntry {
        uint16_t normalized_video_format;
-       unsigned width, height;
+       unsigned width, height, second_field_start;
        unsigned extra_lines_top, extra_lines_bottom;
        unsigned frame_rate_nom, frame_rate_den;
        bool interlaced;
 };
 
-bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *height, unsigned *extra_lines_top, unsigned *extra_lines_bottom,
+bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *height, unsigned *second_field_start,
+                         unsigned *extra_lines_top, unsigned *extra_lines_bottom,
                          unsigned *frame_rate_nom, unsigned *frame_rate_den, bool *interlaced)
 {
        *interlaced = false;
 
        // TODO: Add these for all formats as we find them.
-       *extra_lines_top = *extra_lines_bottom = 0;
+       *extra_lines_top = *extra_lines_bottom = *second_field_start = 0;
 
        if (video_format == 0x0800) {
                // No video signal. These green pseudo-frames seem to come at about 30.13 Hz.
@@ -1156,6 +1157,7 @@ bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *heigh
                *height = 480;
                *frame_rate_nom = 60000;
                *frame_rate_den = 1001;
+               *second_field_start = *height / 2;  // TODO
                *interlaced = true;
                return true;
        }
@@ -1166,6 +1168,7 @@ bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *heigh
                *height = 576;
                *frame_rate_nom = 50;
                *frame_rate_den = 1;
+               *second_field_start = *height / 2;  // TODO
                *interlaced = true;
                return true;
        }
@@ -1176,22 +1179,23 @@ bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *heigh
        // usually it doesn't mean anything.
        uint16_t normalized_video_format = video_format & ~0xe808;
        constexpr VideoFormatEntry entries[] = {
-               { 0x0143, 1280,  720, 25,  5,    50,    1, false },  // 720p50.
-               { 0x0103, 1280,  720, 25,  5,    60,    1, false },  // 720p60.
-               { 0x0121, 1280,  720, 25,  5, 60000, 1001, false },  // 720p59.94.
-               { 0x01c3, 1920, 1080,  0,  0,    30,    1, false },  // 1080p30.
-               { 0x0003, 1920, 1080, 20, 25,    30,    1,  true },  // 1080i60.
-               { 0x01e1, 1920, 1080,  0,  0, 30000, 1001, false },  // 1080p29.97.
-               { 0x0021, 1920, 1080, 20, 25, 30000, 1001,  true },  // 1080i59.94.
-               { 0x0063, 1920, 1080,  0,  0,    25,    1, false },  // 1080p25.
-               { 0x0043, 1920, 1080,  0,  0,    25,    1,  true },  // 1080p50.
-               { 0x008e, 1920, 1080,  0,  0,    24,    1, false },  // 1080p24.
-               { 0x00a1, 1920, 1080,  0,  0, 24000, 1001, false },  // 1080p23.98.
+               { 0x0143, 1280,  720,   0, 25,  5,    50,    1, false },  // 720p50.
+               { 0x0103, 1280,  720,   0, 25,  5,    60,    1, false },  // 720p60.
+               { 0x0121, 1280,  720,   0, 25,  5, 60000, 1001, false },  // 720p59.94.
+               { 0x01c3, 1920, 1080,   0,  0,  0,    30,    1, false },  // 1080p30.
+               { 0x0003, 1920, 1080, 582, 20, 25,    30,    1,  true },  // 1080i60.
+               { 0x01e1, 1920, 1080,   0,  0,  0, 30000, 1001, false },  // 1080p29.97.
+               { 0x0021, 1920, 1080, 582, 20, 25, 30000, 1001,  true },  // 1080i59.94.
+               { 0x0063, 1920, 1080,   0,  0,  0,    25,    1, false },  // 1080p25.
+               { 0x0043, 1920, 1080,   0,  0,  0,    25,    1,  true },  // 1080p50.
+               { 0x008e, 1920, 1080,   0,  0,  0,    24,    1, false },  // 1080p24.
+               { 0x00a1, 1920, 1080,   0,  0,  0, 24000, 1001, false },  // 1080p23.98.
        };
        for (const VideoFormatEntry &entry : entries) {
                if (normalized_video_format == entry.normalized_video_format) {
                        *width = entry.width;
                        *height = entry.height;
+                       *second_field_start = entry.second_field_start;
                        *extra_lines_top = entry.extra_lines_top;
                        *extra_lines_bottom = entry.extra_lines_bottom;
                        *frame_rate_nom = entry.frame_rate_nom;

diff --git a/bmusb.h b/bmusb.h
index 2ed7308648f3df399b7fca778a22d42015461af9..d47ce8e85c4541be65dcd89c7b10ed727781b153 100644 (file)
--- a/bmusb.h
+++ b/bmusb.h
@@ -157,8 +157,11 @@ class BMUSBCapture {
 
 // Get details for the given video format; returns false if detection was incomplete.
 // Note: Frame rate is _frame_ rate, not field rate. So 1080i60 gets 30/1, _not_ 60/1.
-// TODO: Add another extra_lines_ parameter for interlaced.
-bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *height, unsigned *extra_lines_top, unsigned *extra_lines_bottom,
+// "second_field_start" is only valid for interlaced modes; it signifies
+// how many lines from the very top of the frame there are before the second field
+// starts (so it will always be >= height/2 + extra_lines_top).
+bool decode_video_format(uint16_t video_format, unsigned *width, unsigned *height, unsigned *second_field_start,
+                         unsigned *extra_lines_top, unsigned *extra_lines_bottom,
                          unsigned *frame_rate_nom, unsigned *frame_rate_den, bool *interlaced);
 
 #endif