2016-06-20 9:57 GMT+02:00 Michael Niedermayer <mich...@niedermayer.cc>:
> On Sun, Jun 19, 2016 at 11:42:42PM +0200, Eric Beuque wrote: > > 2016-06-19 16:14 GMT+02:00 Michael Niedermayer <mich...@niedermayer.cc>: > > > > > On Sun, Jun 19, 2016 at 09:59:22AM +0200, Eric Beuque wrote: > > > > 2016-06-18 13:46 GMT+02:00 Michael Niedermayer > <mich...@niedermayer.cc>: > > > > > > > > > On Fri, Jun 17, 2016 at 07:26:59PM +0200, Eric Beuque wrote: > > > > > > 2016-06-17 19:16 GMT+02:00 Michael Niedermayer > > > <mich...@niedermayer.cc>: > > > > > > > > > > > > > On Fri, Jun 17, 2016 at 05:39:23PM +0200, Eric Beuque wrote: > > > > > > > > Hi, > > > > > > > > > > > > > > > > i'm posting here for a feature that is missing in ffmpeg (or > may > > > be i > > > > > > > > missed something), which consist of decoding H.264 frame > with a > > > > > scaling > > > > > > > > factor of 1/2, 1/4, 1/8... > > > > > > > > > > > > > > > > I found the parameter lowres, which works well with MJPEG > stream > > > but > > > > > it's > > > > > > > > not working with the H.264 decoder. > > > > > > > > > > > > > > > > I don't know if it's something possible to implement in the > > > decoder, > > > > > but > > > > > > > if > > > > > > > > yes, my compagny agreed to sponsor the feature (depending on > the > > > > > cost of > > > > > > > > course), if a developer qualified is interested to do it. > > > > > > > > > > > > > > > > Is someone know if it is possible, and if it can exist > someone > > > > > interested > > > > > > > > to develop this feature? > > > > > > > > > > > > > > is it acceptable if the encoder enforces some restrictions on > the > > > used > > > > > > > features ? > > > > > > > > > > > > > > most general h264 likely cannot efficiently be decoded in lower > > > > > > > resolution with acceptable quality > > > > > > > Restricting the used intra modes may make it possible to do it > > > though > > > > > > > i dont know what the quality would be but better than without > > > > > > > restrictions > > > > > > > > > > > > > > [...] > > > > > > > > > > > > > > > > > > > > > > > > > Actually, the main goal is for motion detection algorithm, so we > need > > > > > small > > > > > > resolution and best quality is not required. We just need good > > > estimation > > > > > > for the moving pixel. > > > > > > > > > > > > For now, we decode in H.264, and scale it close 320x240, the > then we > > > > > > perform motion detection on it. The goal is to speed up the > process > > > and > > > > > > reduce the memory usage since decoding a 2048x1536 picture lead > > > around a > > > > > 5 > > > > > > MB for the decoded image in memory. > > > > > > > > > > > > So i think it could be OK. > > > > > > > > > > i dont think that withut restrictions it would be good enough for > > > > > motion detection > > > > > > > > > > > > > I don't really understand what will be changed in the decoder with or > > > > without restriction... > > > > > > some of the features of h.264 will not decode "right" without the > > > full resolution > > > > > > > Ok what features do you mean? Maybe it's out of our scope. > > some restrictions on intra modes > constrained intra prediction at least > The GOP size should be small too and there may be other things > like disabling the loop filter > > cant you just use the IP camera in lower resolution if memory is a > problem ? maybe it can encode 2 streams of different resolution > Actually, we are already doing this, but sometimes it's not possible, because some camera are not able to deliver two stream. It's just a question to know if there is a way to improve the usage in that case. If you tell me it's not, we will deal with that. > > [...] > > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > No great genius has ever existed without some touch of madness. -- > Aristotle > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
