30.06.2017, 22:43
I tried ignoring all input timecodes, and that didn't make a difference.
I do now see what you're seeing though with the FFmpeg file - I just tested it on my mac using MPV for playback and had no issues vs. on my Windows, where I'm using MPC-HC for playback, which means that there's something in that stream that some decoders don't like. It also looks like MPV was simply skipping the bad GOP on the mp4box encoded file which made it look like it was working by simply dropping the first 8 seconds. Dropbox, who reencodes the files into H.264 for the web look, seems to have forced a constant frame rate to the FFmpeg version and that 'fixed' it, but for the reencode the one done with Mp4box holds the first valid frame for 8 seconds at the start of that video.
I can't seem to wrap my head around this because x265 which is encoding both the files muxed in MP4box and FFmpeg shouldn't be doing anything different between the two streams and its something in the way that FFmpeg is wrapping it? I'll keep doing some tests on my end to see what happens with other decoding applications.
I do now see what you're seeing though with the FFmpeg file - I just tested it on my mac using MPV for playback and had no issues vs. on my Windows, where I'm using MPC-HC for playback, which means that there's something in that stream that some decoders don't like. It also looks like MPV was simply skipping the bad GOP on the mp4box encoded file which made it look like it was working by simply dropping the first 8 seconds. Dropbox, who reencodes the files into H.264 for the web look, seems to have forced a constant frame rate to the FFmpeg version and that 'fixed' it, but for the reencode the one done with Mp4box holds the first valid frame for 8 seconds at the start of that video.
I can't seem to wrap my head around this because x265 which is encoding both the files muxed in MP4box and FFmpeg shouldn't be doing anything different between the two streams and its something in the way that FFmpeg is wrapping it? I'll keep doing some tests on my end to see what happens with other decoding applications.