diff --git a/cinelerra-5.1/cinelerra/filempeg.C b/cinelerra-5.1/cinelerra/filempeg.C
index 986ac92..504825a 100644
--- a/cinelerra-5.1/cinelerra/filempeg.C
+++ b/cinelerra-5.1/cinelerra/filempeg.C
@@ -622,10 +622,16 @@ int FileMPEG::open_file(int rd, int wr)
 			sprintf(string, " -F %d", frame_rate_code);
 			strncat(mjpeg_command, string, sizeof(mjpeg_command));
 
+			sprintf(string, " -H"); /* Maximise high-frequency resolution */
+			strncat(mjpeg_command, string, sizeof(mjpeg_command));
 
-
-
-
+			if(asset->vmpeg_preset == 3) /* no constrains for mpeg2 generic */
+			{
+			sprintf(string, " --no-constraints");
+			strncat(mjpeg_command, string, sizeof(mjpeg_command));
+			}
+			
+			
 			strncat(mjpeg_command,
 				asset->vmpeg_progressive ? " -I 0" : " -I 1",
 				sizeof(mjpeg_command));