We will do some more testing and report back on how the cx18 handles it. -Jeff
On Sun, Feb 8, 2009 at 8:25 AM, Hans Verkuil <[email protected]> wrote: > On Sunday 08 February 2009 14:01:34 Jeff Campbell wrote: > > > > "Variable and constant bit rate up to 15 Mb/sec" under Features and > > > > Benefits / Video Encoding > > > > > > > > At the moment the cx18 still reports 27 Mbps as the max in v4l2-ctl > > > > -L, which I think is just a carry over from the earlier 15/16 chip. > > > > Just wanted to flag it before it slipped my mind. > > > > > > I put it low on the list, because mucking with those means more > > > regression testing than normal to make sure I didn't screw up the ivtv, > > > pvrusb2, cx88, or cx23885 drivers, as they all call out to those too > > > (IIRC). > > > > I suspected that might be the case, just wanted to mention it before I > > forgot. > > > > In a similar vein, we were doing some testing with VBR versus CBR last > > night and noticed that the current structure, which I believe is also > > carried over from ivtv, does not allow changing the bitrate on the fly. > > However, the chip does allow changing the bitrate on the fly, but > > changing that will also create regression issues potentially. However, > > that being said, I used to be able to change the BR on the fly with ivtv > > and some time in the last year or so it changed so you could not write > > that while the device was in use. Not sure why that was done, perhaps for > > a different device in the same family? > > If I remember correctly I disabled it for ivtv after experimentation showed > that changing the bitrate while capturing would sometimes (always? Can't > remember...) result in a corrupt stream. At least the cx23415/6 seems to be > very sensitive to changes in the compression parameters or in the video > format coming from the video digitizer. Perhaps the cx23418 can handle that > better, but I have my doubts given that it has the some core hardware. > > Regards, > > Hans > > -- > Hans Verkuil - video4linux developer - sponsored by TANDBERG >
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