Hello. I encountered a very subtle problem when generating DVD files with ffmpeg. In a nutshell: the files I create work with many many DVD players (stand-alone and software players) just fine, but it stumbles and stutters on one hardware player. Since this is not a cheapo player (it is a Pioneer DV-656A, indeed), and the owner never experienced such problems with any DVD, I conclude there must be something wrong with the DVD I made. As I will explain later, it is not a problem of authoring and it is very unlikely to be a problem with muxing (which is also done by ffmpeg). What I want to do is a DVD with a collection of short video clips that I have captured from DVB. So I had a couple of MPEG TS files, which I converted with dvbreplex to PS files (for the sake of a/v sync), then I used avidemux to trim it. So far, so good. Since the source material's resolution is not DVD compliant (something like 528x576), I cannot just replex them to VOB files, but I need to re-encode the video (I keep the original audio, because mp2 is fine). The command line I used: ffmpeg -i <infile> -target dvd -acodec copy -s 720x576 -aspect 4:3 -ildct -ilme -bf 2 -hq -b <bitrate> -pass 1 -passlogfile <filename> -vhook <...> out.vob (and then the same with "-pass 2") I have a python script which creates neat menues and afterwards dvdauthor puts it all together. The symptoms: * The DVD plays fine on my stand alone DVD player (Grundig GDP2400) and some others I tried (Yamaha, Philips). MPlayer, xine, ogle, some Windows softare (don't remember the name) all play the DVD just fine. * With one DVD player (Pioneer DV-656A), the video playback of the ffmpeg generated stuff is terrible: it stumbles and stutters all the way. Usually, after a few seconds you see the video frozen while audio is playing on. After a short time (like a second or so, sometimes much longer), the video is back (and in perfect sync with audio). Only a few seconds later, the same things happens again, sometimes several times, before the player just skips the rest of the current track and goes on with the next one. If you play the same track again, you will notice that the player stumbles at exactly the same places again. You might say that this must be a problem of the player and not ffmpeg's fault. Well, yes. But: that player has no problem with bought DVDs. Also selfmade DVDs with not-ffmpeg-coded material works! DVB grabs (from stations with a DVD compliant resolution like 720x576) work fine. I just use dvbreplex to make a VOB from the TS, and it works fine. I write one DVD with ffmpeg-encoded videos and a DVD-ripped track, a DVB-grabbed track, and mpeg2enc-generated tracks. Everything plays fine, also on that Pioneer player, only the ffmpeg-generated videos stumble. I don't even think that the ffmpeg generated video is not officially DVD compliant. But apart from the official DVD specifications, there might exist some quasi standards. Editors of commercial DVDs and DVB stations might follow this quasi standard and some broken players rely on it. E.g. I found reports on the internet, that some players need to have 2 B-Frames between I/P-Frames, which is certainly not a requirement of the official DVD standard. But all commercial DVD I tried, plus the 720x576-DVB stream I grabbed, do have these two B-frames. So it might not be ffmpeg's fault, but anyway, I am interested in producing DVDs which play everywhere, of course. I mentioned the mpeg2enc-generated material works, but I really would like to stick to ffmpeg, because it's so much faster, it supports two pass encoding, and it is much easier to use than mpeg2enc+mplex. Things I already tried (I'm only talking about the Pioneer player now): I varied the command line options. I tried things like "-sgop", "-bf 0", "-bf 1", "-bf 2", one pass encoding, leaving out "-ildct" and "-ilme", specifying max bitrates of 9000, 7500 or none at all, leaving out "-hq". All this had no effect. When changing some of the command line options, the places at which the video stumble can change. For example, without "-hq", the video was a bit more stable. I have written a small analyzer for the m2v video, just to analyse the sequence of I,P,B frames and see what's in the sequence header and GOP header. For me, everything looks fine and I cannot find a difference to VOBs from other sources. I think the "-sgop" option doesn't work, at least not the way I understand it. Even when supplying that option, the GOP sizes vary. Maybe the problem is even in that area... I have the feeling that the stumbling can be triggered by a very short GOP. E.g. there is one GOP of only 3 frames (I-B-B), and I think this is the place at which the video stumbles first. When using mpeg2enc, I encountered a warning that a scene change was detected, but a new GOP cannot be started because the current one would end up being too short. That might be a hint. But: I have other videos (my menues on the DVD) which have short GOPs only after a minute or so, and they stumble right within the first few seconds. So after all... it doesn't make any sense for me anymore.... So... I apologize for this _long_ mail. Maybe someone has an idea, what option to try, or there is even something that has to be changed in the ffmpeg code. Thanks for your help. And thanks too all ffmpeg developers for ffmpeg! -- Sven Over Stephanienstr. 9 76133 Karlsruhe Telefon: 0721-9204199 http://www.svenover.de/