Hi Klaus, in the iso13818-1 (you can find a copy at http://neuron2.net/library/mpeg2/iso13818-1.pdf), in the section 2.4.2.2 Input to the Transport Stream system target decoder, is explained how the PCR is used to reconstruct the transport stream clock. Giampaolo -----Original Message----- From: vdr-bounces@xxxxxxxxxxx [mailto:vdr-bounces@xxxxxxxxxxx] On Behalf Of Klaus Schmidinger Sent: venerdì 8 gennaio 2010 15.01 To: vdr@xxxxxxxxxxx Subject: Re: PCR pid On 08.01.2010 12:19, Giampaolo Sica wrote: > Hi Klaus, > > Thanks for your answer and sorry for replaying so late. > > Setting Ppid to 0x1FFF means disable it. The effect is that some mpeg2 > players refuse to play vdr recordings. > > I think that the PCR pid is more important in recordings than in live > viewing, because in live viewing the timing is implicit in the packet time > of arrival. When you have a file you lose that information because you try > to fill the playing buffer. > > What I said is anyway wrong, because PCR is part of the mpeg2 standard and > it have to be present in the stream. > > Maybe, the particular implementation of the mpeg2 decoder in the DVB FF card > derives its internal clock using the framerate of the mpeg2 stream, but it > is not standard. Can you point to some documentation that specifies how the PCR data is actually used during replay of a recording? I find it very hard to believe that this can actually be used, because you just can't syncronize a local clock to the PCR if the PCR packets don't arrive in real time. Klaus > -----Original Message----- > From: vdr-bounces@xxxxxxxxxxx [mailto:vdr-bounces@xxxxxxxxxxx] On Behalf Of > Klaus Schmidinger > Sent: sabato 5 dicembre 2009 12:27 > To: vdr@xxxxxxxxxxx > Subject: Re: PCR pid > > On 26.11.2009 13:51, Giampaolo Sica wrote: >>> Maybe because you haven't applied it to your copy of version 1.7.10? ;-) >> :))) >> >>> In hindsight I'm not sure whether the change "Fixed writing the PCR pid >>> into the PMT in cPatPmtGenerator::GeneratePmt()" was a good idea, because >>> VDR doesn't record the PCR pid at all. >>> I tend to revert that change, because I don't think that >>> a separate PCR pid is necessary in a recording. AFAIK the >>> PCR pid is only for live viewing. >>> Klaus >> >> Yes, you're right if you are replaying recordings on a FF card, but: >> >> 1) Some players refuse to play TS streams without PCR information (screen >> remains black). >> 2) I'm porting VDR to IPBOX 9000HD (STi710x based STB... yes, I know there >> is enigma2, but I've been using vdr since 2000 and I love it) and the PCR >> pid is essential to have the timeline while watching recording, because > the >> ioctl DMX_GET_STC fails and the only way to you get time information is > from >> the video/audio decoder (VIDEO_GET_PTS/ AUDIO_GET_PTS). So, even if I > wrote >> a plugin for this device, I'd have to patch the base classes that is in >> contrast with the plugins philosophy > > Can you please try what happens if you set > > int Ppid = 0x1FFF; > > in cPatPmtGenerator::GeneratePmt()? > > As far as I understand the PCR (please correct me if I'm wrong), it only > has a meaning in live mode, where PCR packets arrive at precise points in > time and are used to syncronize the player's internal clock. > When replaying a recording, it is not defined when the PCR packets arrive > at the player, and thus they have no meaning. > > Klaus _______________________________________________ vdr mailing list vdr@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/vdr _______________________________________________ vdr mailing list vdr@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/vdr
