Felix Domke wrote: > Johannes Stezenbach wrote: > > >The V4 API has: > > > > unsigned int frame_rate; /* in frames per 1000sec */ > > > > > I'm against this. > > The reason is that arbitrary framerates are not allowed in MPEG-2 > (correct me if i'm wrong, i'm currently too lazy to read 13818-2 > again...), and there's no hardware being able to playback this simply > because there's no TV standard for arbitrary framrates. > > I use the framerate to decide wheter to have a PAL or NTSC stream, or > better: if the stream is more likely to comply with the NTSC standard or > the PAL standard (or in future any HDTV standard). I think handling the > "odd" framerates (23.976 etc.) is hard enough - what is the application > expect to do if the framerate becomes, for example, 31337? (switching to > eTSC?) Dropping frames and do simple NTSC? > Seriously, are there are really real-world-cases where the enum proposed > by Andreas isn't enough? I really would like to restrict us here to the > real-world framerates, since only this will give you the possibility to > handle all values correctly. > > After all, we don't want to insert any "frame rate drift" etc. here, > since that's not what the value should say. It should only give a hint > wheter to display the source in NTSC or PAL and maybe some informational > output. > > (Of course if someone tells me that arbitrary framerates are of any(!) > use, i'll change my position here, but after all, it's a DVB-API, not a > generic stream playback API. MPEG was restricted to a set of discret > frame rates, because it's simply impossible to build a decoder which > supports all frame rates without doing complex pullup/downs).
DVB has TV oriented requirements (i.e. frame rate matching PAL or NTSC), but MPEG-2 can also be used for special purpose stuff like CCTV or info terminals (used in public places like museums), where low frame rates are sufficient. Also, newer STB/DVD chips might support MPEG-4 or other codecs, and you cannot predict what frame rates you have to deal with. But of course no one expects a STB to play back everything flawlessly, it's just that IMHO the DVB API should allow for some non-DVB extensions. Regards, Johannes -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.