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 [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB No great genius has ever existed without some touch of madness. -- Aristotle
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