Set a FFmpeg-private JPEG marker to signal some Y'CbCr information.

[nageru] / nageru / mjpeg_encoder.cpp

diff --git a/nageru/mjpeg_encoder.cpp b/nageru/mjpeg_encoder.cpp
index 3587d78dcf3fa51a61a92af89ec362b3297b2d3e..614cb5cc8836a80b3eb4831d91a1465c8cd4a73e 100644 (file)
--- a/nageru/mjpeg_encoder.cpp
+++ b/nageru/mjpeg_encoder.cpp
@@ -389,6 +389,10 @@ void MJPEGEncoder::init_jpeg_422(unsigned width, unsigned height, VectorDestinat
        cinfo->comp_info[2].v_samp_factor = 1;
        cinfo->CCIR601_sampling = true;  // Seems to be mostly ignored by libjpeg, though.
        jpeg_start_compress(cinfo, true);
+
+       // This comment marker is private to FFmpeg. It signals limited Y'CbCr range
+       // (and nothing else).
+       jpeg_write_marker(cinfo, JPEG_COM, (const JOCTET *)"CS=ITU601", strlen("CS=ITU601"));
 }
 
 vector<uint8_t> MJPEGEncoder::get_jpeg_header(unsigned width, unsigned height, jpeg_compress_struct *cinfo)