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. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
