Hello, I've recently received some H264 videos marked as AVC3: Duration: 00:29:00.00, start: 0.000000, bitrate: 949 kb/s Stream #0:0(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 125 kb/s (default) Metadata: handler_name : SoundHandler Stream #0:1(und): Video: h264 (Main) (avc3 / 0x33637661), yuvj420p(pc, bt709), 704x396 [SAR 1:1 DAR 16:9], 819 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default) Metadata: handler_name : VideoHandler Stream #0:2: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 192x108 [SAR 72:72 DAR 16:9], 90k tbr, 90k tbn, 90k tbc These are not natively playable by quicktime/iTunes under OSX High Sierra (10.13.1). I can obviously convert them into H264 avc1 the long way, but wondered if there was a quick way of simply changing the metadata of the avc3 stream into avc1? I've tried splitting the audio and video into two streams, and then remuxing. This worked, but the video was "jerky" and unwatchable. Thanks for your help. Ant.