2016-06-20 0:35 GMT+02:00 Ivan Kalvachev <ikalvac...@gmail.com>: > On 6/17/16, Eric Beuque <eric.beu...@gmail.com> 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. > > Have you tried to extract the motion vectors of the H.264 stream itself? > > If the encoder supports more than I-frames, it should do some Motion > Estimation. >
No, but i don't really know how it is working. Our goal is to split the picture in 1024 block and telling which block has motion detection or not. Do we have a motion vectors for the I-Frame it self? I assume no, but i actually need motion detection in any frame. > _______________________________________________ > 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
