+
+struct VideoFormatEntry {
+ uint16_t normalized_video_format;
+ int width, height;
+ int frame_rate_den, frame_rate_nom;
+ bool interlaced;
+};
+
+bool decode_video_format(uint16_t video_format, int *width, int *height, int *frame_rate_den, int *frame_rate_nom, bool *interlaced)
+{
+ *interlaced = false;
+
+ if (video_format == 0x0800) {
+ // No video signal. These green pseudo-frames seem to come at about 30.13 Hz.
+ // It's a strange thing, but what can you do.
+ // FIXME: find the dimensions.
+ *frame_rate_nom = 3013;
+ *frame_rate_den = 100;
+ return true;
+ }
+ if ((video_format & 0xe800) != 0xe800) {
+ printf("Video format 0x%04x does not appear to be a video format. Assuming 60 Hz.\n",
+ video_format);
+ *width = 0;
+ *height = 0;
+ *frame_rate_nom = 60;
+ *frame_rate_den = 1;
+ return false;
+ }
+
+ // NTSC (480i59.94, I suppose). A special case, see below.
+ if (video_format == 0xe901 || video_format == 0xe9c1 || video_format == 0xe801) {
+ *width = 640;
+ *height = 480;
+ *frame_rate_nom = 60000;
+ *frame_rate_den = 1001;
+ *interlaced = true;
+ return true;
+ }
+
+ // PAL (576i50, I suppose). A special case, see below.
+ if (video_format == 0xe909) {
+ *width = 720;
+ *height = 576;
+ *frame_rate_nom = 50;
+ *frame_rate_den = 1;
+ *interlaced = true;
+ return true;
+ }
+
+ // 0x8 seems to be a flag about availability of deep color on the input,
+ // except when it's not (e.g. it's the only difference between NTSC
+ // and PAL). Rather confusing. But we clear it here nevertheless, because
+ // usually it doesn't mean anything.
+ uint16_t normalized_video_format = video_format & ~0xe808;
+ constexpr VideoFormatEntry entries[] = {
+ { 0x0143, 1280, 720, 50, 1, false }, // 720p50.
+ { 0x0103, 1280, 720, 60, 1, false }, // 720p60.
+ { 0x0121, 1280, 720, 60000, 1001, false }, // 720p59.94.
+ { 0x01c3, 1920, 1080, 30, 1, false }, // 1080p30.
+ { 0x0003, 1920, 1080, 30, 1, true }, // 1080i60.
+ { 0x01e1, 1920, 1080, 30000, 1001, false }, // 1080p29.97.
+ { 0x0021, 1920, 1080, 30000, 1001, true }, // 1080i59.94.
+ { 0x0063, 1920, 1080, 25, 1, false }, // 1080p25.
+ { 0x0043, 1920, 1080, 25, 1, true }, // 1080p50.
+ { 0x008e, 1920, 1080, 24, 1, false }, // 1080p24.
+ { 0x00a1, 1920, 1080, 24000, 1001, false }, // 1080p23.98.
+ };
+ for (const VideoFormatEntry &entry : entries) {
+ if (normalized_video_format == entry.normalized_video_format) {
+ *width = entry.width;
+ *height = entry.height;
+ *frame_rate_nom = entry.frame_rate_nom;
+ *frame_rate_den = entry.frame_rate_den;
+ *interlaced = entry.interlaced;
+ return true;
+ }
+ }
+
+ printf("Unknown video format 0x%04x. Assuming 720p60.\n", video_format);
+ *width = 1280;
+ *height = 720;
+ *frame_rate_nom = 60;
+ *frame_rate_den = 1;
+ return false;
+}