OK this is apparently just a consequence of colorspace conversion--not a libva thing. Not sure if there is really a way to address it since going from BGR to NV12 data is gonna be lost because there are fewer bits.
Just running this pipeline in gstreamer 1.2.2 shows a lot of change in the image: gst-launch-1.0 filesrc location=Howdy.png ! decodebin ! videoconvert ! video/x-raw,format=NV12 ! videoconvert ! imagefreeze ! ximagesink On Wed, Oct 8, 2014 at 11:07 AM, Chris Healy <[email protected]> wrote: > I assume the black and white image is acceptable as it looks the same > whereas the color one has some visual degradation, correct? > > The i3 is Haswell based whereas the i5 is an older SandyBridge. I know > the Haswell is faster encode and decode wise, but I don't know about > quality. Is there a difference visually between the older i5 and newer i3 > quality wise? > > What are you using to do your color space conversion? I've been using one > of the VPPs but was previously using libyuv on the CPU. > > On Wed, Oct 8, 2014 at 9:02 AM, Matt Pekar <[email protected]> > wrote: > >> I've examined the behavior on Intel(R) Core(TM) i3-4130 and Intel(R) >> Core(TM) i5-2400. We target resolutions as low as 224x64 and up to 720P. >> >> Another thing I'm noticing is that the colors used seem to matter. I put >> some white on black text up and it looks great. Maybe there is an issue >> with how I do my colorspace conversion from BGR to NV12... >> >> I'm going to attempt to attach two pictures of what I'm seeing. They >> show the original .png image and what the encoder delivers side by side. >> >> On Wed, Oct 8, 2014 at 10:41 AM, Chris Healy <[email protected]> wrote: >> >>> Hi Matt, >>> >>> I've been using the libva with the Intel driver to encode and stream >>> myself for quite some time now. There are a number of visual artifacts >>> that I have encountered along the way, though the fuzziness you describe is >>> not one of them. With the Intel driver, I would expect different visual >>> behaviour depending on the particular HW you are using as each one is >>> different. I'm using an i7-3517U to encode 1280x720 H.264 at 4Mbps. What >>> are you working with? >>> >>> Chris >>> >>> On Wed, Oct 8, 2014 at 7:18 AM, Matt Pekar <[email protected] >>> > wrote: >>> >>>> We use libva with the Intel driver to do live video streaming. In the >>>> encoding process we dynamically ramp the QP up and down as different >>>> content flows through. >>>> >>>> There are cases where we display simple text messages for many >>>> seconds. In these cases I'd like to send my QP down to 1--highest >>>> quality--and get as close to a lossless encode as possible. >>>> >>>> What I'm seeing is that on fonts and sharp lines a little bit of >>>> encoding will be done regardless, leaving the text slightly fuzzy. I tried >>>> the new VAEncMiscParameterTypeQualityLevel setting, but it only had two >>>> levels (1 and 2) and they didn't seem to affect the picture at all. >>>> >>>> Are there any settings I might try to ramp the quality up even >>>> further? Is the fuzziness I'm seeing in the text inherent to the h264 >>>> standard, or is this just what Intel's implementation happens to do? >>>> >>>> >>>> _______________________________________________ >>>> Libva mailing list >>>> [email protected] >>>> http://lists.freedesktop.org/mailman/listinfo/libva >>>> >>>> >>> >> >
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